Hysteres glidande medelvärde

Magnetisk hysteres Fördröjningen eller fördröjningen av ett magnetiskt material som vanligtvis är känt som magnetisk hysteres. avser magnetiseringsegenskaperna hos ett material genom vilket det först magnetiseras och sedan magnetiseras. Vi vet att magnetflödet som alstras av en elektromagnetisk spole är mängden magnetfält eller kraftlinjer som produceras inom ett visst område och att det vanligtvis kallas 8220Flux Density8221. Med tanke på symbolen B med flödestäthetenheten är Tesla, T. Vi vet också från tidigare tutorials att magnetens styrka av en elektromagnet beror på antalet varv av spolen, strömmen strömmar genom spolen eller typen av kärnmaterial används, och om vi ökar antingen strömmen eller antalet varv kan vi öka magnetfältets styrka, symbol H. Tidigare definierades den relativa permeabiliteten, symbol 956 r som förhållandet av den absoluta permeabiliteten 956 och permeabiliteten hos det fria utrymmet 956 o (ett vakuum) och detta gavs som en konstant. Relationen mellan flödestätheten, B och den magnetiska fältstyrkan, H kan emellertid definieras av det faktum att den relativa permeabiliteten 956 r inte är en konstant men en funktion av magnetfältintensiteten och ger därmed magnetisk flödestäthet som: B 956 H. Då ökas den magnetiska flödestätheten i materialet med en större faktor som ett resultat av dess relativa permeabilitet för materialet jämfört med den magnetiska flödestätheten i vakuum, 956 ° H och för en luftkärlspole ges detta förhållande som: Så för ferromagnetiska material är förhållandet mellan flödestäthet och fältstyrka (032 BH 032) inte konstant men varierar med flödestäthet. För luftkärnspolar eller någon icke-magnetisk mediumkärna, såsom trä eller plast, kan detta förhållande emellertid betraktas som en konstant och denna konstant är känd som 956 o. permeabiliteten för ledigt utrymme, (032 956 o 061 4,960,10 -7 Hm 032). Genom att plotta värden på flödestäthet, (032 B 032) mot fältstyrkan, (032 H 032) kan vi producera en uppsättning kurvor som kallas magnetiseringskurvor. Magnetic Hysteresis Curves eller mer vanligen B-H-kurvor för varje typ av kärnmaterial som används som visas nedan. Magnetisering eller B-H-kurva Satsen magnetiseringskurvor, M ovan representerar ett exempel på förhållandet mellan B och H för järn - och stålkärnor, men varje typ av kärnmaterial kommer att ha sin egen uppsättning magnetiska hystereskurvor. Du kanske märker att flödestätheten ökar i proportion till fältstyrkan tills den når ett visst värde, var det inte kan öka att det blir nästan nivå och konstant, eftersom fältstyrkan fortsätter att öka. Detta beror på att det finns en gräns för den mängd flödestäthet som kan genereras av kärnan, eftersom alla domäner i järnet är perfekt anpassade. En eventuell ytterligare ökning kommer inte att ha någon effekt på värdet på M. och punkten i diagrammet där flödesdensiteten når gränsen kallas magnetisk mättnad även känd som mättnad av kärnan och i vårt enkla exempel ovanför mättpunkten för stålkurvan börjar vid ca 3000 ampere-varv per meter. Mättnad uppstår, eftersom det som vi kommer ihåg från den tidigare magnetism-tutorialen som inkluderade Weber8217s teori förändras det slumpmässiga slumpmässiga arrangemanget av molekylstrukturen i kärnmaterialet som de små molekylmagneterna i materialet blir 8220-linjerade upp8221. När magnetfältstyrkan (032 H 032) ökar blir dessa molekylmagneter mer och mer inriktade tills de når perfekt inriktning som ger maximal flödestäthet och en ökning i magnetfältstyrkan på grund av en ökning i den elektriska strömmen som strömmar genom spolen har liten eller ingen effekt. Retentivitet Vi antar att vi har en elektromagnetisk spole med hög fältstyrka på grund av att strömmen strömmar genom den och att det ferromagnetiska kärnmaterialet har nått sin mättnadspunkt, maximal flödestäthet. Om vi ​​nu öppnar en strömbrytare och tar bort magnetiseringsströmmen som strömmar genom spolen, förväntar vi oss att magnetfältet runt spolen försvinner när magnetflödet sänks till noll. Det magnetiska flödet försvinner emellertid inte helt, eftersom det elektromagnetiska kärnmaterialet fortfarande behåller en del av sin magnetism även när strömmen har slutat flöda i spolen. Denna förmåga för en spole att behålla en del av sin magnetism i kärnan efter att magnetiseringsprocessen har stoppats kallas Retentivitet eller remanens, medan den mängd flödestäthet som kvarstår i kärnan kallas återstående magnetism. B R 160. Anledningen till detta är att några av de små molekylmagneterna inte återvänder till ett helt slumpmässigt mönster och fortfarande pekar i riktning mot det ursprungliga magnetiseringsfältet vilket ger dem en slags 8220memory8221. Vissa ferromagnetiska material har en hög retentivitet (magnetiskt hård) vilket gör dem perfekta för att producera permanenta magneter. Medan andra ferromagnetiska material har låg retentivitet (magnetiskt mjuk) vilket gör dem ideala för användning i elektromagneter, solenoider eller reläer. Ett sätt att reducera denna återstående flödestäthet till noll är genom att vända strömriktningen som strömmar genom spolen, varigenom värdet av H. magnetfältstyrkan negativ. Denna effekt kallas en tvångskraft. H C 160. Om denna omvänd ström ökar ytterligare kommer flödestätheten också att öka i omvänd riktning tills den ferromagnetiska kärnan når mättnad igen men i omvänd riktning från tidigare. Att reducera magnetiseringsströmmen, jag återigen till noll, kommer att producera en liknande mängd restmagnetism men i omvänd riktning. Sedan genom att ständigt ändra magnetiseringsströmens riktning genom spolen från en positiv riktning till en negativ riktning, vilket skulle vara fallet i en AC-matning, kan en magnetisk hysteres-slinga av den ferromagnetiska kärnan framställas. Magnetic Hysteresis Loop Den magnetiska Hysteresis-slingan ovan visar grafiskt beteendet hos en ferromagnetisk kärna, eftersom förhållandet mellan B och H är icke-linjärt. Från och med en magnetiserad kärna kommer både B och H att vara nollpunkt 0 på magnetiseringskurvan. Om magnetiseringsströmmen ökas i positiv riktning till något värde ökar magnetfältstyrkan H linjärt med i och flödestätheten B kommer också att öka som visas av kurvan från punkt 0 till punkt a när den går mot mättnad. Om nu magnetiseringsströmmen i spolen reduceras till noll reduceras magnetfältet som cirkulerar runt kärnan också till noll. Spolarens magnetiska flöde når emellertid inte noll på grund av den kvarvarande magnetismen som finns i kärnan och detta visas på kurvan från punkt a till punkt b. För att minska flödestätheten vid punkt b till noll måste vi vända strömmen genom spolen. Den magnetiserande kraft som måste appliceras för att nollställa den återstående flödestätheten kallas en 8220Coercive Force8221. Denna tvångskraft reverserar magnetfältet och återställer molekylmagneterna tills kärnan blir magnetiserad vid punkt c. En ökning i denna omvänd ström leder till att kärnan magnetiseras i motsatt riktning och att öka denna magnetiseringsström ytterligare kommer att få kärnan att nå sin mättpunkt, men i motsatt riktning, punkt d på kurvan. Denna punkt är symmetrisk till punkt b. Om magnetiseringsströmmen reduceras igen till noll kommer den kvarvarande magnetism som är närvarande i kärnan att vara lika med föregående värde men i omvänd punkt vid punkt e. Återigen kommer den magnetiserande strömmen som strömmer genom spolen denna gång till en positiv riktning att medföra att magnetflödet når nollpunkten, punkt f på kurvan, och som tidigare ökar magnetiseringsströmmen ytterligare i en positiv riktning kommer kärnan att nå mättnad vid punkt a. Därefter följer B-H-kurvan banan av a-b-c-d-e-f-a då magnetiseringsströmmen som strömmar genom spolen växlar mellan ett positivt och negativt värde, såsom cykeln hos en växelspänning. Denna väg kallas en magnetisk hysteresis loop. Effekten av magnetisk hysteres visar att magnetiseringsprocessen för en ferromagnetisk kärna och därmed flödesdensiteten beror på vilken del av kurvan den ferromagnetiska kärnan magnetiseras på eftersom detta beror på kretsarna tidigare historia, vilket ger kärnan en form av 8220memory8221. Sedan har ferromagnetiska material minne eftersom de förblir magnetiserade efter det att det yttre magnetfältet har tagits bort. Mjuka ferromagnetiska material, såsom järn eller kiselstål, har emellertid mycket smala magnetiska hysteresloops, vilket resulterar i mycket små mängder återstående magnetism, vilket gör dem ideala för användning i reläer, solenoider och transformatorer, eftersom de lätt kan magnetiseras och demagnetiseras. Eftersom en tvångskraft måste appliceras för att övervinna denna kvarstående magnetism, måste arbete göras när hysteresslingan stängs med den energi som användes förloras som värme i det magnetiska materialet. Denna värme är känd som hysteresförlust, mängden förlust beror på materialets värde av tvångskraft. Genom tillsats av additiv8217s till järnmetallen såsom kisel kan material med en mycket liten tvångskraft tillverkas som har en mycket smal hystereslinga. Material med smala hystereslingor magnetiseras lätt och demagnetiseras och är kända som mjuka magnetiska material. Magnetic Hysteresis Loops för mjuka och hårda material Magnetic Hysteresis resulterar i spridning av slösad energi i form av värme med den bortspillade energin i proportion till området för den magnetiska hysteresloopen. Hysteresförluster kommer alltid att vara ett problem i växelströmstransformatorer där strömmen ständigt ändrar riktningen och sålunda kommer de magnetiska polerna i kärnan att orsaka förluster eftersom de ständigt vänder sig mot riktningen. Roterande spolar i DC-maskiner kommer också att medföra hysteresförluster eftersom de växelvis sträcker sig norrut i södra magnetpolerna. Som tidigare sagt beror formen på hysteresslingan på typen av det använda järnet eller stålet och i fallet med järn som utsätts för massiva magnetismomvandringar, t ex transformerkärnor, är det viktigt att BH hysteresslingan är som liten som möjligt. I nästa handledning om elektromagnetism. Vi kommer att titta på Faraday8217s lag för elektromagnetisk induktion och se till att genom att flytta en ledare i ett stationärt magnetfält är det möjligt att inducera en elektrisk ström i ledaren som producerar en enkel generator. Föregående The ElectromagnetTheory amp Definitioner Senast ändrad: 17 februari 2013 Att ansluta ett mätinstrument på rätt sätt är bara en sak. Men för att bestämma rätt parameter behöver fler överväganden. Mycket viktigt är frågan: För vilket syfte gör jag denna mätning Genom att utföra en strömmätning för att undersöka värmeutvecklingen i en tråd krävs en annan parameter än en strömmätning för att bestämma laddningsstatus för en kondensator eller ett batteri. Parametrar kan uttryckas som ett medelvärde, RMS, momentant eller toppvärde. Inte bara typen av last är viktig, men också om det här är en AC eller DC-källa, och hur spänningen och strömmen ser ut. Den närbesläktade interaktionen mellan spänning och ström, och kraft och energi å andra sidan kommer att diskuteras på denna sida. Instantaneous värden Den momentana spänningen v. nuvarande i och kraft p har ett värde som motsvarar en viss tid t. Varje vågform har ett oändligt antal momentana värden. En sådan vågform beskrivs som parametern som en funktion av tiden. Vid spänning kommer det att skrivas som v (t). I exemplet nedan är situationen för en seriekrets av ett motstånd och en spole ansluten till en sinusformad spänning med en toppspänning på 3 V och en frekvens f av 50 Hz. Fig. 1: Spänning, ström och effekt som funktion av tiden. Den sinusformade spänningen som funktion av tiden är skriven som: equ. 1 Strömmen har ett högsta värde av 2 A och förskjuts 60 i förhållande till spänningen. ekv. 2 Kraften som funktion av tiden är produkten av motsvarande momentana värden för spänning och ström: ekv. 3 Figur 1 visar den grafiska representationen av spänning, ström och effekt. Som exempel visas de momentana värdena för tiden t 4,2 ms markerad med den grå linjen: v (4,2 ms) 2,906 V i (4,2 ms) 0,538 A p (4,2 ms) 1,563 W Vid en viss tid kan den momentana spänningen och strömmen alltid multipliceras för att beräkna den momentana effekten. Medelvärden Medelvärdet, även kallat medelvärdet, är den vanligaste parametern. Om en multimeter är inställd för mätning av DC-värden, mäts medelspänningen eller strömmen. Även medelvärdet för en växelspänning eller ström mäts när mätaren är inställd på likström. Vid en symmetrisk växelspänning kommer multimetern att indikera 0 V, vilket är rätt värde. Spänning och ström Medelvärdet är summan av alla produkter av de momentana värdena x multiplicerat med den oändligt små tiden dt dividerad med perioden T, vari mäts. Denna summering med oändligt små tidssteg kallas integrera. Generellt skrivet som: equ. 4 X kan exempelvis representera spänningen eller strömmen. Fyllt i för spänningen: equ. 5 Multimeter Fig. 2: Ett RC-filter är medelvärdet för spänningen. Som tidigare nämnts mäter en multimeter som är vald i ett DC-intervall medelvärdet av spänningen eller strömmen. I digitala mätare fastställs detta medel medelst ett RC-filter. Detta är ingångssignalen medelfristig i genomsnitt under RC-tiden. I formelform: equ. 6 Energi och kraft Ekvation 3 visar att produkten av den momentana spänningen och strömmen resulterar i den momentana effekten p (t). Om dessa momentana krafter multiplicerade med den oändligt små tiden dt summeras kontinuerligt, kommer den att returnera energin i systemet sedan t 0 s: equ. 7 I själva verket är energi kraften multiplicerad med tiden: E Pt, och energipaket kan alltid läggas ihop för att beräkna den totala energin. Nedan visas signalerna igen från exemplet spole-resistenta seriekretsen som diskuteras i momentant värden. I denna figur representerar den svarta linjen energianvändningen i tid som beräknad med ekvation 7. Fig. 3: Energi som funktion av tiden. Som en följd av spänningen och strömens växlande polaritet har effektkurvan också en periodisk växlingsamplitud med dubbel frekvens. Eftersom energi släpps ut i motståndet är det gråfärgade positiva området av effektkurvan större än det negativa området. Värdet på den svarta energilinjen vid vilken tidpunkt som helst är lika med det föregående området under effektkurvan. Det är uppenbart att energinivån periodiskt stiger mer än den faller som följd av amplitudasymmetrin hos effektkurvan runt x-axeln. I figur 3 anges tidsperioden T. Energin inuti denna tid (0. T s) som sätts in i systemet indikeras med E per och kommer att beräknas enligt följande: equ. 8 Den genomsnittliga effekten över en viss tidsperiod är lika med den totala mängden energi inom den tiden dividerad med tiden i vilken mäts: ekv. 9 Om denna division vid tiden införs i ekv. 8 kan medelvärdet beräknas för vilken vågform som helst: ekv. 10 Denna ekvation överensstämmer med den allmänna ekvationen för att beräkna ett medelvärde (ekv. 4). Den aktiva kraften är alltid den genomsnittliga effekten. Denna ekvation för att beräkna den genomsnittliga effekten är alltid giltig eftersom beräkningen är baserad på momentana värden. Det spelar ingen roll om det här är direkt eller växelström, hur spänningen och strömmen ser ut, eller huruvida det finns fasförskjutning mellan spänning och ström. Ekvationen ovan för att beräkna medelvärdet är den metod med vilken driften av en effektmätare är baserad på. En energimätare som en kilowatt-timmarsmätare hos hus och industrier fungerar enligt jämförelse 8. Eller på annat sätt skrivet som: ekv. 11 Den övre gränsen T för integralet är den tidpunkt då energimätaren är avläsning. RMS-värden RMS-värdet eller det effektiva värdet är ett värde för en spänning eller ström som liknar en lika stor effekt i ett motstånd som en likspänning eller ström med samma värde. En växelspänning med ett effektivt värde på 230 V kommer att utveckla samma mängd värme i ett motstånd som en ren likspänning på 230 V. RMS-värdet gäller endast värmeutvecklingen i en resistiv belastning. Som exempel: RMS strömmen är användbar för att övervaka belastningens belastning (resistiv), men inte att mäta laddningsströmmen från ett batteri eller en kondensator (elektronflöde). Root Mean Square RMS är en förkortning för Root Mean Square. Spänningen eller strömmen som funktion av tiden kommer successivt att genomgå tre matematiska operationer: kvadrera, medelvärde och kvadratrots, för att beräkna RMS-värdet. Varför dessa operationer äger rum förklaras nedan: Effekten i ett motstånd som är anslutet till en spänning beräknas med: ekv. 12 För momentan kraft och spänning kommer detta att vara: equ. 13 Hur man beräknar medelvärdet som funktion av tiden visades i ekvation 10. p (t) kan fyllas i ekvation 13 ovan: ekv. 14 Eftersom motståndet R är en konstant kan det föras fram: ekv. 15 När spänningen från ekvation 12 flyttas till vänster sida av lika tecken kan spänningen beräknas utifrån medelkraft och motstånd: ekv. 16 När den genomsnittliga effektberäkningen från ekv. 15 fylls i ekvationen 16 ovan: ekv. 17 Båda motståndsvärdena R i utdelningen och divisorn eliminerar varandra och kan utelämnas. Detta resulterar i ekvationen som beräknar RMS-värdet för varje slumpmässig spänningsvågform: equ. 18 Det är tydligt att se att ekvationen består av tre delar: kvadrat v (t) 2. medelvärde och kvadratroten. Den ovan beskrivna analysen beräknas med en spänning över ett motstånd. För strömmar genom ett motstånd kan en jämförande utvärdering göras. Resultatet för RMS-strömmar kommer än att vara: equ. 19 Fig. 4: Huvudkrets för en analog RMS-beräkning. De flesta multimetrar kan inte beräkna RMS-värdet från den uppmätta spänningen. Att känna till RMS-värdet behövs vanligtvis ett speciellt instrument. Kretsen i figur 4 visar hur en RMS-mätare den uppmätta spänningen beräknar. En RMS-mätare i praktiken kommer att använda en något annorlunda arbetsmetod, varigenom endast en multiplikator behövs. Analog multiplikatorer måste ha en mycket låg temperatur och offset drift, vilket gör dessa instrument dyra. Det är också möjligt att göra RMS-beräkning med mjukvara med de fortsatta digitaliseringsvärdena för de uppmätta spänningarna. Detta tillvägagångssätt används vanligen med multimetrar och digitala oscilloskop. Pseudo RMS De flesta multimetrar mäter inte RMS-värdet när områdesväljaren är inställd på växelströmsläge. Ändå verkar de ge det effektiva värdet vid mätning av AC-spänningar och strömmar. Men de visade värdena är endast giltiga när en sinusformad vågform mäts. En enkel AVO-mätare korrigerar den uppmätta signalen först. Sedan destillerade ett följande RC-lågpassfilter det genomsnittliga värdet. Detta resulterande medelvärde är än skalat så att instrumentet visar det effektiva värdet. Skriven som en ekvation: equ. 20 Konsekvensen av detta tillvägagångssätt är att den endast är användbar för sinusformade vågformer. Varje annan formad vågform kommer att ge ett felaktigt effektivt värde. RMS-kraft Särskilt i ljudsamhällen finns en överdriven användning av termen RMS-ström eller P RMS. Detta är per definition en felaktig term. Som i kapitlet Medelvärden under rubriken Energi och kraft visas att arbetskraften beräknas utifrån den totala energimängden dividerad med den tid då denna energi mäts (ekv. 9). Den totala energin definieras genom summering av alla momentana energipaket v (t) i (t) dt (ekv. 11). Detta är det enda rätta sättet att beräkna den aktiva kraften. Som tidigare förklarat är RMS-värdet ekvivalent med en likspänning eller ström som utvecklade samma effekt i samma motstånd. Detta beräknas av kvadratroten från medelvärdet av den momentana spänningen (eller strömmen) i kvadrat. Det finns ingen anledning att tänka varför dessa tre matematiska operationer ska tillämpas på momentan kraft. Detta skulle vara ett nonsensiskt värde. ekv. 21 Fig. 5: Beräkna effekten på olika sätt och jämföra detta med en RMS-effektberäkning. För att illustrera detta görs en beräkning av sinusformad spänning med en amplitud av 2 Vtt och en frekvens av 1 kHz. Ovanför grafen är definitionerna: Lastmotståndet R är 4 Omega. Som en funktion av tiden beräknas: sinusformad spänning v (t). den nuvarande i (t) och effekten p (t). I diagrammet visas spänning och ström. Först beräknas RMS-spänningen av spänningen som en funktion av tiden v (t). Resultatet är lika med den välkända ekvationen: Den andra ekvationen beräknar RMS-strömmen med strömmen som en funktion av tiden i (t). Detta är lika med: Då, med tre olika metoder, beräknas den aktiva effekten med hjälp av RMS-spännings - och strömvärdena: V RMS I RMS. V RMS 2 I RMS 2 R. För att kontrollera detta, med en fjärde beräkning bestäms medelvärdet med effekten som funktion av tiden p (t). Alla dessa beräkningar ger samma värde för aktiv eller genomsnittlig effekt. Äntligen, i botten beräknas RMS-effekten. Resultatet av detta (0,153 W) skiljer sig avsevärt från de fyra tidigare beräkningarna (0,125 W). Ovanstående exempel utförs med en sinusformad spänning och ström. Men formen av spänning och ström samt typ av belastning och eventuellt fasskifte är av underordnad betydelse. Den aktiva kraften är alltid den genomsnittliga effekten. RMS Power är ett nonsensiskt nummer. Laddar kommentarer, vänta. Batteri och energiteknik Notera - Du kan också använda sökmotorn för att snabbt hitta det du söker. - Ytterligare detaljer är tillgängliga genom att följa länkarna AC-omformare - En elektrisk krets som genererar en sinusvågsutgång (reglerad och utan paus) med likströmmen som levereras av likriktarens laddare eller batteriet. Omriktarens primära delar är DCAC-omvandlaren, ett reglersystem och ett utgångsfilter. AD Converter (ADC) AnalogueDigital Converter. En anordning som omvandlar kontinuerligt varierande analoga signaler till en binär kodad digital form. Syra - En protongivare. En förening innehållande väte som dissocierar i vattenhaltig lösning som producerar positivt laddade vätejoner (H). En sur lösning har ett pH lägre än 7,0 Aktivt material - De kemiskt reaktiva materialen i en energicell som reagerar med varandra, omvandlar från en kemisk sammansättning till en annan, samtidigt som man producerar elektrisk energi eller tar emot elektrisk ström från en extern krets. Åldrande - Permanent förlust av kapacitet vid frekvent användning eller tidsåtgång på grund av oönskade irreversibla kemiska reaktioner i cellen. AGM (Absorptive Glass Mat) batteri - Ett blybatteri med en glasmatta för att främja rekombination av de gaser som produceras av laddningsprocessen. Alkali - En förening som löser upp i vatten som producerar negativt laddade hydroxidjoner. Alkaliska lösningar är starka basiska och neutraliserar syror som bildar ett salt och vatten. Alkaliskt batteri - Ett batteri som använder en alkalisk alkalisk lösning för elektrolyt. Allotrope - Två eller flera former av samma element i samma fysiska tillstånd (fast, flytande eller gas) som skiljer sig från varandra i sina fysiska och ibland kemiska egenskaper. Termen allotropi gäller endast element, inte föreningar. Den mer allmänna termen, vilken används för något kristallint material, är polymorfism. Se även isotop. Omgivningstemperatur - Medeltemperaturen kring batteriet, normalt luft. Amorf - Utan bestämd form eller struktur, utan kristallin struktur. Ampere (Amp) - Enheten för strömflöde är lika med en coulomb per sekund. Ampere timmar (Ah) eller Amphours - Den måttenhet som används för att jämföra kapaciteten eller energiinnehållet hos en batterier med samma utgångsspänning. För de flesta batterier definieras batterys C-hastighet. För bilbatterier (blybatterier) definierar SAE Amphour-kapaciteten som 20 gånger den ström som levereras under en period av 20 timmar när batteriet är urladdat vid 1 tjugonde av C-hastigheten tills cellspänningen sjunker till 1,75 volt. Strängt - En Ampere-timme är laddningen överförd av en amp som strömmar i en timme. 1Ah 3600 Coulombs. Batteriets sanna kapacitet är dess energiinnehåll och detta mäts i WattHours (Wh). Det är batterys Amphour-kapacitet multiplicerat med batterispänningen. Ampullbatteri - Ett batteri där elektrolyten lagras i en separat kammare från cellelektroderna tills batteriet behövs. Analog (analog) krets - En elektronisk krets där ett elektriskt värde (vanligtvis spänning eller ström, men ibland frekvens, fas) representerar någonting i den fysiska världen. Storleken på det elektriska värdet varierar med intensiteten hos en yttre fysisk kvantitet. Också - En elektrisk krets som ger en kontinuerlig kvantitativ utgång (i motsats till en digital utgång som kan vara en serie pulser eller tal) som svar på dess ingång. Anechoic chamber - Ett rum vars väggar inte speglar antingen elektromagnetiska eller akustiska vågor. Anjon - Partiklar i elektrolyten av en galvanisk cell som bär en negativ laddning och rör sig mot anoden under drift av cellen. Se också katjon Anisotropisk - Visar skillnader i egendom eller effekt i olika riktningar. Anod - Elektroden i en elektrokemisk cell där oxidation sker, frigör elektroner. Under urladdning är den negativa elektroden av cellen anoden. Under laddning återgår situationen och cellens positiva elektrod är anoden. ANSI - American National Standards Institute publicerar standarder för batterier tillsammans med NEMA. (Se nedan) Vattenlösning - Kemiska komponenter i flytande eller gelform. Arrhenius ekvation - Relationen mellan hastigheten vid vilken en kemisk reaktion fortsätter och dess temperatur. I allmänhet ökar värmen den kemiska verkan. Monterat batteri - Ett batteri som består av två eller flera celler. Atomtal - Specifikt för enskilda element - representerar antalet protoner i atomkärnan. Samma som antalet elektroner. Atommassa - Antal nukleoner (protoner och neutroner) i atomkärnan. Augeranalys - Liknar ESCA men ger inte information om elementets kemiska tillstånd (oxidation etc.). Autentisering - Verifiering att ett objekt är från en godkänd källa och att den kan uppfylla den angivna specifikationen. Avogadros Antal (N A) - Antalet atomer i 12 gram Carbon-12 (definition) 6,022 x 10 23. I tillägg, antalet partiklar i 1 mol av en substans. Bas - En protonacceptor. En förening innehållande väte som dissocierar i vattenhaltig lösning som producerar negativt laddad hydroxid (OH-) eller andra joner. Alkalier är baser och en baslösning har ett pH större än 7,0 Batteri - Två eller flera elektrokemiska energikällor kopplade ihop för att ge elektrisk energi. Batterihanteringssystem (BMS) - Elektroniska kretsar som är konstruerade för att övervaka batteriet och hålla det inom de angivna driftsförhållandena och för att skydda den från missbruk under både laddning och urladdning. Batteriövervakning - Ibland förväxlas med BMS (ovan) som det är en väsentlig del, övervakar dessa kretsar de viktigaste driftsparametrarna (ström, spänning, temperatur, SOC, etc.) på batteriet och ger information till användaren. Spole - En cylindrisk celldesign med användning av en inre cylindrisk elektrod och en yttre elektrod anordnad som en hylsa inuti cellbehållaren. Bootstrap - Att göra något som verkar omöjligt med endast tillgängliga resurser. I samband med DC-batterikretsar betyder det att man genererar en likspänning som är högre än batterispänningen. Brittiska värmeenheter (BTU) - En enhet av värmeenergi definierad som den mängd värme som krävs för att höja temperaturen på ett pund vatten med en grad Fahrenheit. En Btu är lika med ca 252 kalorier, eller 778 fot pund, eller 1.055 kilojoule eller 0,293 watt timmar. Buck regulator - En växelregulator som inkorporerar en DC-DC-omvandlare. En transformerlös design där den lägre utspänningen uppnås genom att haka ingångsspänningen med en seriekopplad strömbrytare (transistor) som applicerar pulser till en medelvärdesinduktor och kondensator. Butler Volmer ekvation - Används av celldesigners för att förutsäga strömmen som kommer att strömma i ett batteri. Det är summan av de anodiska och katodiska bidragen och är direkt proportionell mot elektrodens yta, vilket ökar exponentiellt med temperaturen. Knappcell - Miniatyrcylindrisk cell med en karakteristisk skivform. C Programmeringsspråk - Det föredragna programmeringsspråket för inbyggd programvara som används i många batterihanteringsprogram. Robust, snabb och kraftfull, det tillåter låg nivå tillgång till information och kommandon samtidigt som portabiliteten och syntaxen på ett högnivå språk fortfarande behålls. C Rate - C är ett värde som uttrycker nominell strömkapacitet för en cell eller ett batteri. En cellutmatning vid C-hastigheten kommer att leverera sin nominella nominella kapacitet i 1 timme. Laddnings - och urladdningsströmmar uttrycks i allmänhet som multiplar av C. Tiden att ladda ut ett batteri är omvänd proportionellt mot urladdningsgraden. NC är en laddnings - eller utladdningshastighet som är N gånger batteriets nominella strömkapacitet där N är ett tal (fraktion eller flera) CN är batterikapaciteten i AmpHours vilket motsvarar att batteriet är fullständigt utloppet om N timmar (N är vanligtvis ett prenumeration). Också skrivet som N-timmars hastighet. Kalenderliv - Den förväntade livslängden för en cell om den är aktiv eller i lagring CAN Bus - Controller Area Network Automotive industry standard för inbyggda fordonskommunikation. Det är en seriell kommunikationsbuss med två ledningar som används för nätverk av intelligenta sensorer och ställdon. Kalorimeter - En apparat eller kammare för mätning av värmen som genereras av föremål placerade inuti den. Kapacitans (C) - En mätning av förmågan hos en anordning att lagra laddning per spänningsenhet som är anbringad över anordningen. CQV Farads. Kapacitansen hos en parallellplatta kondensator ges av C epsilon Ad där epsilon är permeabiliteten hos dielektriska. A är plåtarna (elektroderna) och d avståndet mellan dem. 1 Farad 1 Coulomb per volt. (Q V) Strömmen genom kondensatorn ges av förhållandet i C d dt V (t) Kondensator - En passiv elektrisk enhet som lagrar energi i ett elektriskt fält. Kapacitet - Batteriets elektriska energiinnehåll uttryckt i Watt timmar. Batterier med samma utgångsspänning använder även Ampere-timmar för att jämföra kapacitet. Kapacitetsförskjutning - En korrigeringsfaktor som tillämpas på batteriernas klassificering om de släpps ut under olika C-värden från den nominella. Catalyst - A chemical agent which promotes or influences a chemical reaction without itself being permanently changed by the reaction. Used in recombinant cells and fuel cells Cathode - The electrode in an electrochemical cell where reduction takes place, gaining electrons. During discharge the positive electrode of the cell is the cathode. During charge the situation reverses and the negative electrode of the cell is the cathode. Cation - Particles in the electrolyte of a galvanic cell carrying a positive charge and moving towards the cathode during operation of the cell. See also anion CCA - Cold Cranking Amperes - A measure used to specify the cold cranking capability of automotive SLI batteries. For Lead Acid batteries it is the constant current a battery can deliver during a continuous discharge over a period of 30 seconds at -18degC without the terminal voltage dropping below a minimum of 1.2 Voltscell. CE - The CE marking indicates that the product has been designed and manufactured in conformity with the essential requirements of all relevant EU directives, and submitted to the relevant conformity assessment procedure. Cell - A closed electrochemical power source. The minimum unit of a battery. Cell balancing - The process used during charging to ensure that every cell is charged to the same state of charge. Also called Equalisation. Cell chemistry - The active materials used in the energy cell. Cell reversal - A condition which may occur multi cell series chains in which an over discharge of the battery can cause one or more cells to become completely discharged. The subsequent volt drop across the discharged cell effectively reverses its normal polarity. Charge - The process of replenishing or replacing the electrical charge in a rechargeable cell or battery. see also Electric charge Charge acceptance - The ability of a secondary cell to convert the active material to a dischargeable form. A charge acceptance of 90 means that only 90 of the energy can become available for useful output. Also called Coulombic Efficiency or Charge Efficiency. See alternative definition below. Charge carriers - The particle carrying the electrical charge during the flow of electrical current. In metallic conductors the charge carriers are electrons. while ions carry the charges in electrolyte solutions. Charge efficiency - The ratio (expressed as a percentage) between the energy removed from a battery during discharge compared with the energy used during charging to restore the original capacity. Also called the Coulombic Efficiency or Charge Acceptance. See alternative definition above. Charge pump - A power supply which uses capacitors instead of inductors to store and transfer energy to the output. A voltage doubler or tripler. Charge rate - The current at which a cell or battery is charged. Generally expressed as a function of rated capacity C . Charge retention - The ability of a battery to retain its charge in zero current conditions. Charge retention is much poorer at high temperatures. See also Self Discharge Charge, state of - The available or remaining capacity of a battery expressed as a percentage of the rated capacity. Charge transport - The movement of electrical charge from one part of the system to another, occurring through the drift of ions under the influence of electrical potential difference. Also called Electromigration . Chemical species - Atoms, molecules, molecular fragments, ions, etc. as entities being subjected to a chemical process or to a measurement. CID Circuit Interrupt Device - A small mechanical switch which interrupts the current through an energy cell if the internal pressure exceeds a predetermined limit. Usually applied in small cells only. Coercivity - The resistance of a ferromagnetic material to becoming demagnetised. Measured in Oersteds. Coin cell - Small cylindrical cell with a disc shape. Conditioning - Cycle charging and discharging to ensure that formation (see below) is complete when a cell enters service or returns to service after a period of inactivity Conductance - Strictly speaking the Conductance applies to resistive circuits and is the reciprocal of the Resistance. Battery manufacturers have their own definition which applies to the frequency dependent elements of the circuit, that is - C IE where C is the conductance, I is the test current applied to a component (the cell) and E is the in phase component of the ac voltage E producing it.(Compare with Ohms Law REI ) Measuring the conductance of a battery gives a good indication of its state of health. Conducting polymer - Plastic materials which have some of the properties of metals. Used as solid electrolytes in batteries. Also used in the construction of fuel cell membranes, capacitor electrodes and in applications requiring anti-static plastics. (See also Polymer below) Constant current charge CC - A charging scheme which maintains the current through the cell at a constant value. Constant voltage charge CV - A charging scheme which maintains the voltage across the battery terminals at a constant value. Contacts - The battery output terminals. Conversion Efficiency - The percentage of the input energy of a process that is converted to energy of the desired type. Coulomb - A unit of electric charge. One coulomb (1C) is equal to the charge transferred by a current of one ampere in one second. Coulomb Counting - A method of determining the state of charge of a battery by integrating the ingoing and outgoing discharge currents of a battery over time. Coulombic Efficiency - The ratio (expressed as a percentage) between the energy removed from a battery during discharge compared with the energy used during charging to restore the original capacity. Also called Charge Efficiency or Charge Acceptance . Coup de fouet (Whiplash) - A dramatic initial voltage drop when a battery is suddenly called upon to supply a heavy load. The voltage recovers after a short time once the electro-chemical discharge process stabilises. Critical Temperature (Superconductor) - The temperature below which a superconducting material must be cooled in order to exhibit the property of superconductivity .(See below) CSA - The Canadian Standards Association is a not-for-profit membership-based association serving business, industry, government and consumers in Canada and the global marketplace. Curie point or Curie temperature - The temperature above which a ferromagnets and some other materials undergo a sharp change in their magnetic properties losing their ability to possess a net spontaneous or remanent magnetization in the absence of an external magnetic field. Current limit - The maximum current drain under which the particular battery will perform adequately under a continuous drain. Current shunt - A current shunt is an low value resistance, whose value is accurately known, placed in series between the battery and the load. The voltage drop across the shunt is used to determine the value of the current using Ohms Law. Used in series, it is not a shunt in the literal sense of the word. Its name derives from the fact that early ammeters could not handle high currents and the shunt was used to bypass most of the current around the meter. Cut-off voltage - The specified voltage at which the discharge of a cell is considered complete. See also End voltage and Termination voltage CVT - Constant Voltage Transformer Cycle - A single charge and discharge of a battery. Cycle life - The number of cycles a battery can perform before its nominal capacity falls below 80 of its initial rated capacity. See also Float life below. Cylindrical cell - A cell in which the electrodes are rolled up in a spiral and placed into a cylindrical container. DA Converter (DAC) DigitalAnalogue Converter - A device which converts a digitally coded signal into an equivalent analogue signal. DC-DC Converter - An electronic circuit which takes a DC input voltage and converts it to a different, desired DC output voltage. Deep cycle battery - A battery designed to be discharged to below 80 Depth of Discharge. Used in marine, traction and EV applications. Deep discharge - Discharge of at least 80 of the rated capacity of a battery. Delta V - The voltage drop which occurs in some cells, notably NiCads, which indicates that the cell is fully charged. Dendritic growth - The formation from small crystals in the electrolyte of tree like structures which degrade the performance of the cell. Depth of discharge DOD - The ratio of the quantity of electricity or charge removed from a cell on discharge to its rated capacity. Diamagnetism - The property of a substance which is repelled instead of attracted by a magnet. A diamagnetic material will be repelled from a magnet no matter what pole it is near. It is exhibited by all common materials, but is very weak and often swamped by stronger paramagnetic or ferromagnetic effects. Metals such as bismuth, copper, gold, silver and lead, as well as many nonmetals such as graphite, water and most organic compounds are diamagnetic. See also Ferromagnetism and Paramagnetism. Dielectric - A nonconductor of electricity, such as an insulator, or a substance in which an electric field can be maintained with a minimum loss of power. The material used between two conducting plates to form a capacitor. When a dielectric or insulator is placed in an electric field, electric charges do not flow through the material but shift only slightly from their average equilibrium positions causing the dielectric to become polarised with a positive charge on one side and a negative charge on the other. Dielectric Constant - Used to determine the ability of an insulator to store electrical energy. The dielectric constant is the ratio of the capacitance induced by two metallic plates with an insulator between them to the capacitance of the same plates with air or a vacuum between them. Discharge - The change from chemical energy within the cell into electrical energy to operate a external circuit. Discharge capacity - The amount of energy taken from the battery when discharged at the rated current and ambient temperature until the discharge end voltage is reached. Generally expressed in units of Watt hours (or Ampere hours for batteries with the same voltage). Discharge rate - The current delivered by the cell during discharging. Expressed in Amperes or multiples of the C rate . Discharge voltage - The voltage between the terminals of a cell or battery under load, during discharge. DOD - Depth of Discharge (see above) Dropout - In a voltage regulator, the lower limit of the AC input voltage where the power supply just begins to experience insufficient input to maintain regulation. The dropout voltage for linears is quite load dependent. For most switchers it is largely design dependent, and to a smaller degree, load dependent. Dry Cell - A Leclancheacute cell with a gel electrolyte. DST - Dynamic Stress Test. Accelerated battery life tests specified by the USABC. Cycling down to 80 DOD twice per day at different temperatures. Duty Cycle - The load current or power a battery is expected to supply for specified time periods. dTdt - The rate of change of temperature with time. The rapid rate of temperature rise is used to detect the end of the charging cycle in NiMH batteries. ECE-15 - The United Nations Economic Commission for Europe specification for urban driving cycle simulation. E Rate - Discharge or charge power, in watts, expressed as a multiple of the rated capacity of a cell or battery which is expressed in watt-hours. For example, the E10 rate for a cell or battery rated at 23.4 watt-hours is 2.34 watts. (This is similar to the method for calculating C-Rate.) Elastomer - elastic or plastic materials that resemble rubber which resume their original shape when a deforming force is removed. Electret - The electrostatic equivalent of the permanent magnet. Dielectric materials that have been permanently electrically charged or polarised. Electric charge is a physical property of matter which causes it to experience a force when near other electrically charged matter. The charge may be positive or negative. Similar charges repel each other while opposite charges attract each other. The unit of electric charge is the Coulomb (C). Electrochemical equivalent - The weight of a substance which is deposited by the passage of one coulomb of current. Electrode - Conducting element within a cell in which an electrochemical reaction occurs. Electrode potential - The voltage developed by a single electrode, determined by its propensity to gain or lose electrons. Electrolysis - Chemical modifications, oxidation and reduction produced by passing an electric current through an electrolyte. See also Faradays Law of Electrolysis Electrolyte - A substance which dissociates into ions (charged particles) when in aqueous solution or molten form and is thus able to conduct electricity. It is the medium which transports the ions carrying the charge between the electrodes during the electrochemical reaction in a battery. Electromotive Force EMF - The ability of an electrical source to deliver energy. It is the difference of potentials which exists between the two electrodes of opposite polarity in an electrochemical cell. Also known as the Cell voltage . The unit of EMF is the Volt. Embedded System - A special-purpose computer system, which is completely encapsulated within the device it controls, usually performing a limited range of specific pre-determined tasks. This allows the use of simpler or cheaper dedicated microprocessors providing only the minimum functionality required by the application, or alternatively the entire processing power of the microprocessor can be focused on a single task. Battery Management Systems will normally be implemented with an embedded system. EMC - Electromagnetic compatibility (EMC) is the ability of electronic and electrical equipment and systems to operate without adversely affecting other electrical or electronic equipment or being affected by other sources of electromagnetic interference. (RFI) End voltage - The prescribed voltage that indicates that the discharge is complete. (see also Cut-off voltage ) Endothermic - Describes a chemical action in which heat is absorbed. Energy Content - The absolute amount of energy stored in a battery expressed in Wh or Joules Energy density - The amount of energy stored in a battery. It is expressed as the amount of energy stored per unit volume or per unit weight (WhL or Whkg). Enthalpy - The amount of energy released or absorbed by a chemical reaction. The quotFree Enthalpyquot (also called the quot Change in Gibbs Free Energyquot) in a reaction is the maximum amount of chemical energy available from a system that can be converted into electrical or mechanical energy and vice versa. (discharge and charge respectively) Entropy - A measure of the disorder of a system. Used as a measure of heat content. EPROM - Electronically Erasable Programmable Read-Only Memory. Re-writable memory that does not lose data if power is lost to the system (non-volatile). Available in three types: OTP One Time Programmable non-erasable. Windowed (ultraviolet light erasable) used for prototyping and development work. EEPROM Electronically Erasable Programmable Read-Only memory. Equalisation - The process of bringing every cell in a battery chain to the same state of charge (SOC) ESCA - Electron Spectroscopy for Chemical Analysis. Equipment using x-ray irradiation to identify the presence of individual chemical elements particularly for surface coatings and thin films where it can be used for selected element depth profiling. A machine typically costs about 750,000 EUDC - Extra Urban Driving Cycle. European additional specification for urban driving cycle simulation. EUROBAT - The Association of European Storage Battery Manufacturers. (Mainly Lead acid) Eutectic - A mixture in such proportions that the melting-point is as low as possible, the constituents melting simultaneously. Exercise - Commonly describes the discharging to one volt per cell and subsequent charging. Used to maintain or condition NiCad and NiMH cells. Exothermic - Describes a chemical action in which heat is produced. Farad - The charge in Coulombs necessary to change the potential between the plates of a capacitor by 1 volt. 1 Farad 1 Coulomb per Volt. (Q V) Faraday cage - An enclosure with no apertures (holes, slits, windows or doors) made of a perfectly conducting material. No electric fields are produced within the Faraday cage by the incidence of external fields upon it or by currents flowing on the perfect conductor such that the perfectly conducting enclosure is a perfect electromagnetic shield. Faraday constant - The magnitude of electric charge per mole of electrons or protons. It is equal to Avogadros Number times the charge on the electron. F N A. e Faradays Law of Electrolysis - The mass of a substance altered at an electrode during electrolysis is directly proportional to the quantity of electrical charge (measured in Coulombs ) transferred at that electrode. Faradays Law of Induction - The induced EMF in a closed circuit is proportional to the rate of change of the magnetic flux through the circuit. see also Inductance Fast charge - Charging in less than one hour at about 1.0C rate. Needs special charger. FCC - The Federal Communications Commission is an independent United States government agency charged with regulating interstate and international communications by radio, television, wire, satellite and cable. Ferromagnetism - The property of a substance which is attracted to a magnet. Iron, cobalt, nickel, gadolinium, dysprosium and alloys containing these elements are ferromagnetic. See also Diamagnetism and Paramagnetism. FET - Field Effect Transistor - A semiconductor device designed for fast, current switching applications. Firmware - Instructions programmed into a micro-controller that controls its operation. A combination of hardware and software. FIT (Failures in Time) is defined as he failure rate per billion (10 9 ) hours. FlexRay Bus - A fault tolerant, high speed data communications bus designed for complex automotive control applications. Float charge - An arrangement in which the battery and the load are permanently connected in parallel across the DC charging source, so that the battery will supply power to the load if the charger fails. Compensates for the self-discharge of the battery. Float life - The expected lifetime in hours of a battery when used in a float charge application. See also Cycle life above. Flooded Lead Acid cell - In flooded batteries, the oxygen created at the positive electrode is released from the cell and vented into the atmosphere. Similarly, the hydrogen created at the negative electrode is also vented into the atmosphere. This can cause an explosive atmosphere in an unventilated battery room. Furthermore the venting of the gasses causes a net loss of water from the cell. This lost water needs to be periodically replaced. Flooded batteries must be vented to prevent excess pressure from the build up of these gasses. See also Sealed Lead Acid (SLA) Cells which overcome these problems. Flow battery - A battery in which the electrolyte flows or is pumped through the electrodes Flywheel battery - A flywheel stores kinetic energy in a high speed (up to 100,000 rpm) rotating cylinder and is charged and discharged via an integral motorgenerator. High power availability but low capacity. Formation - Electrochemical processing of a cell electrode(or plate) between manufacturing and first discharge, which transforms the active material into its useable form. FPGA - Field Programmable Gate Array. A microchip which can be made with thousands of programmable logic gates. Often used for prototype or custom designs, they permit short development times and low production costs. FUDS - Federal Urban Driving Schedule specification for urban driving cycle simulation. Fuel Cell - An electrochemical generator in which the reactants are stored externally and may be supplied continuously to a cell. Fuel Gauge - An indication of the State of Charge (SOC) or how much charge is remaining in a battery. Also called a Gas Gauge. Fuzzy Logic - A method of deriving precise answers from vague data. Galvanic cell - An electrolytic cell in which chemical energy is converted to electrical energy on demand Gas chromatography - The separation and identification of individual chemical components from a sample. A typical machine costs over 250,000.. Gas gauge - An electrical circuit which indicates the amount of charge remaining in a battery. Gassing - The generation of a gaseous product at one or both electrodes as a result of the electrochemical action. In Lead Acid batteries gassing produces hydrogen and oxygen. Gel cell - A battery which uses gelled electrolyte, an aqueous electrolyte that has been fixed by the addition of a gelling agent. GMR (Giant MagnetoResistance) A spintronic effect that produces a large change in resistance of the conducting layers that occurs when thin stacked layers of ferromagnetic and nonmagnetic materials are exposed to a magnetic field. Giant refers to its very large electrical signal. The technology is used to manufacture current and magnetic sensors. Gravimetric Energy Density (WhKg) - The energy output per unit weight of a battery. Gravimetric Power Density (WKg) - The power output per unit weight of a battery. Ground Fault Interruptor - Also called an Earth Leakage Trip - A safety device which disconnects the mains power if an earth leakage (unsafe) condition is detected. A sensing coil detects fault currents from the live wire to the earth (ground) wire and switches off the power when a predetermined threshold is reached. The device is designed to protect the electrical installation from faults and does not sense fault currents from the live wire to any other earthed body. See also Residual Current Device (RCD) which also protects the user. Ground Loop - An unintentionally induced feedback loop or crosstalk caused by two or more circuits sharing a common electrical ground. Half Cell Reaction - The electrochemical reaction between the electrode and the electrolyte. Hall effect - When a fixed conductor carrying an electric current is placed in an external magnetic field perpendicular to the current there is voltage drop across the conductor at right angles to the current which is proportional to the magnetic field. Used to measure magnetic field strength. Heavy Duty battery - An ill defined battery characteristic. See Battery Performance . Henry (H) - The unit of inductance. The inductance L in a circuit 1 Henry if the rate of change of the current of 1 Ampre per second in the circuit produces an EMF of 1 Volt. 1 Henry 1 Weber per Amp (Wb A) Hertz (Hz) - The standard unit of frequency of one cycle per second. HEV - Hybrid Electric Vehicle (See below) Hibernation state - A state in which the the status of the various functions of a circuit has been saved in memory and the circuit has been switched off save energy. When power is reapplied, data taken from the memory is used to restore the circuit to the status it had before switch off. (See also Standby state below) High Energy battery - An ill defined battery characteristic. See Battery Performance . High rate discharge - Discharge at a current of 2C or more. Horse Power (Hp) - The rate of doing work. 1 Hp 746 Watts or 550 foot pounds per second. Hybrid Electric Vehicle (HEV) - A vehicle which has two forms of motive power one of which is electric. Hydrometer - A device used for measuring the specific gravity of a fluid. In the case of lead acid batteries the specific gravity provides a measure of the state of charge of the cell. Hygrometer - An instrument for measuring humidity. Often confused with a hydrometer. Hysteresis - A property of physical and chemical systems that do not instantly follow the forces applied to them, but react slowly, or do not return completely to their original state. In the case of magnetic systems, when an external magnetic field is applied to a magnetic material, the material becomes magnetised absorbing some of the external field. When the external field is removed the material remains magnetised to some extent, retaining some magnetic field. See also hysteresis in batteries. IEC - The International Electrotechnical Commission (IEC), founded in London in 1906, is the leading global organization that prepares and publishes international standards for all electrical, electronic and related technologies. See also Standards IGBT - Insulated Gate Bipolar Transistor. It has the output switching and conduction characteristics of a bipolar power transistor but is voltage controlled like the MOSFET giving the high current carrying capability of the bipolar transistor but the ease of control of the MOSFET. Immobilised electrolyte - A construction technique used in lead-acid batteries. The electrolyte (the acid) is held in place against the plates instead of being a free-flowing liquid. The two most common techniques are Gel Cell and Absorbed Glass Mat . Impedance - A measure of the response of an electric circuit to an electric current. The actual value is frequency dependent. The current is opposed by the capacitance, inductance and resistance of the circuit. Impedance testing - Determination of the batterys internal impedance by measuring the voltage drop across a cell when it carries a sample alternating current. Inductance (L) - A measure of the ability of a device to store magnetic flux per unit of rate of change of current passing through the device. Measured in Henries. 1 Henry 1 Weber per Amp (Wb A) The voltage across the inductor is given by the relationship v - L d dt I(t) Inductive charging - A charger in which the charging current is induced by an external induction coil into a secondary transformer winding housed within the battery together with rectifying and charge control circuits. Inductor - A passive electrical device that stores energy in a magnetic field Infra red radiation - The spectrum of the heat radiated by a warm body. Inhibitor - A substance added to the electrolyte to prevent or slow down an unwanted electrochemical process. Used to prevent corrosion of the electrodes or the formation of dendrites. Insert mouldings - Plastic parts containing metal inserts used to simplify product assembly and reduce costs. Inserts made from metal or other materials are placed in the mould prior to the injection of plastic. The plastic flows around the inserts and fixes their position. Intelligent battery - Battery containing circuitry enabling some communication between the battery and the application or with the charger. Intelligent charger - Charger which is able to react to inputs from an intelligent battery to control or optimise the charging process. Intelligent Energy Manager IEM - A system for reducing the demands that power hungry applications place on the battery. Intercalation - This insertion of ions into the crystalline lattice of a host electrode without changing its crystal structure. Internal impedance - Resistance to the flow of AC current within a cell. It takes into account the capacitive effect of the plates forming the electrodes. Internal resistance - Resistance to the flow of DC electric current within a cell, causing a voltage drop across the cell in closed circuit proportional to the current drain from the cell. A very low internal impedance is usually required for a high rate (high power) cell. Inverter - An electrical circuit which generates a sine-wave output (regulated and without breaks) using the DC current supplied by the rectifier-charger or the battery. The primary elements of the inverter are the DCAC converter, a regulation system and an output filter. Ion - An atom or group of atoms which is electrically charged. Depending on how they were created - through release or absorption of electrons - ions can be either positively charged ( Cations ) or negatively charged ( Anions ). See also Ionisation IP Code - Ingress Protection Rating. It consists of the letters IP followed by two digits. The first digit represents the degree of protection against dust and solids. The second digit represents the degree of protection against moisture and water. IR drop - The voltage drop across a battery due to its internal impedance. See also Ohmic loss below. I 2 R loss - The energy generated or lost as heat due to the internal resistance of the battery. Also known as the Joule heating effect. ISO - A network of national standards institutes from 148 countries, founded in 1946, working in partnership with international organizations, governments, industry, business and consumer representatives. The name, ISO was not intended as an acronym for an International Standards Organisation but was derived from the Greek word isos meaning equal. See also Standards Isotope - Atoms of the same element with the same atomic number ( the same number of protons) but with different numbers of neutrons an hence different weights. See also allotrope . Josephson effect - The flow of electric current through nonconductive material when placed between two superconductors. Used to detect very weak magnetic fields. Joule - quotJquot A measure of work, energy or cell capacity. For electrical energy, one Joule is one Amp at one Volt for one Second, or one WattSecond. 1 Wh 3.6kJ. For mechanical energy one Joule is a force of one Newton acting over one metre i. e. One newton metre. Joule heating - The I 2 R loss or heating effect of a current I flowing through a resistance R . Kalman Filter - A mathematical technique for deriving accurate information from inaccurate data. Kelvin Bridge - An electrical circuit for measuring very low impedances such as battery internal impedance, contact resistance and resistance of circuit elements such as wires and cables. Also known as the Kelvin Connection for voltage sensing. Keyed connectors - Plug and socket pairs with a unique mechanical profile which can only be mated with eachother in a particular orientation and which do not allow mating with connectors of a different design. LDO (Low Drop Out) Regulator - An LDO is a type of linear regulator. Dropout voltage is the minimum input to output voltage differential required for the regulator to sustain an output voltage within 100mV of its nominal value. Leakage - The escape of electrolyte to the outer surface of the battery or cell. Lifetime Energy Throughput - The total amount of energy in Watthours which can be taken out of a rechargeable battery over all the cycles in its lifetime before its capacity reduces to 80 of its initial capacity when new. LIN Bus - Local Interconnect Network An automotive industry standard for on-board vehicle communications. It is a single wire, serial communications bus which is used for networking intelligent sensors and actuators Linear charger - Charger which uses a series regulator. The simplest and cheapest type but less efficient than a Switch mode charger. Linear Regulator - A linear, or Series, regulator is a voltage regulator which uses a transistor or FET in series with the load, operating in its linear region, to subtract excess voltage from the applied input voltage, producing a regulated output voltage. Lithium Ion Cell - A secondary lithium cell in which both the negative and positive electrodes are lithium insertion (intercalation) compounds. Also known as rocking chair, shuttlecock or swing cell. Lithium Polymer Cell - A lithium ion cell with a solid polymer electrolyte. Load current - The discharge current provided by a battery, or drawn by a battery powered device. Long Life battery - An ill defined battery characteristic. See Battery Performance . Magnetic flux density (B) - is the magnetic flux per unit area. B (Phi A) Teslas. The flux density resulting from a magnetic field is given by B muH where mu is the permeability of the medium. Magnetic field strength (H) - is a measure of the magnetic field surrounding a wire (or moving charge). H I (2 pi r) Amps per metre, where I is the current in the wire and r the distance from the wire. Magnetic Resonance Imaging (MRI) - A method of looking inside the human body without using surgery, harmful dyes or x-rays based on Nuclear Magnetic Resonance (NMR ). Magnetohydrodynamic Generator MHD - The production of electricity by passing a conducting fluid or plasma through a magnetic field. Magnetomotive Force (MMF) - is the strength of a magnetic field, or magnetic potential, in a current carrying coil of wire. It is the work that would be required to carry a hypothetical isolated magnetic pole of unit strength completely around a magnetic circuit and is equivalent to the current I multipled by the number of turns N in the coil producing the field. It is expressed in units called ampere-turns (At). The MMF ampere-turns NI Number of turns ( N ) X Current in the wire ( I ) Magnetostriction - A property which causes the shape or dimensions of ferromagnetic materials to change during the process of magnetisation. Mass spectrometer - A device which produces a mass spectrum of a sample to find out its composition by ionising the sample and separating ions of differing masses and recording their relative abundance by measuring intensities of ion flux. Mass spectroscopy allows detection of compounds by separating ions by their unique mass. A typical machine costs around 250,000 Memory effect - Reversible, progressive capacity loss in nickel based batteries found in NiCad and to a lesser extent in NiMH batteries. It is caused by a change in crystalline formation from the desirable small size to a large size which occurs when the cell is recharged before it is fully discharged. Mechanical charging - Charging by replacing one or more of the active chemicals in the cell. Meissner effect - When a superconducting material is cooled below its critical temperature it will exclude or repel a magnetic field. A magnet moving by a conductor induces currents in the conductor. This is the principle upon which the electric generator operates. But, in a superconductor the induced currents exactly mirror the field that would have otherwise penetrated the superconducting material causing the magnetic field to be excluded and magnet to be repulsed. This phenomenon is known as diamagnetism (see above) and is so strong that a magnet can actually be levitated over a superconductive material. Metal hydride - A metallic compound which is able to absorb hydrogen. Used as the negative electrode (anode) of a Nickel Metal Hydride battery. Microcycles - Rapid, shallow charge and discharge cycles which occur in automotive battery applications, particularly those which involve regenerative braking. MISRA - UK Motor Industry Software Reliability Association. Mole (n) - The amount of substance of a system that contains as many elemental entities (e. g. atoms, ions, electrons, molecules) as there are atoms in 12 grams of carbon-12 (Avogadros number of particles). It is an amount, not a physical quality. 1 mole of a pure substance has a mass in grams equal to its molecular mass (M). See also Table of Constants Molar mass - The mass in grams of one mole (or 6.02 x 1023 molecules) of any chemical compound. Monomer - A small molecule that may become chemically bonded to other monomers to form a polymer. From Greek mono one and meros part. Morphology - The microstructure of the solid phases of materials. The grain shapes and structure of crystals of the chemical components of a battery. MOSFET - A Field Effect Transistor made using Metal Oxide Semiconductor technology. Controlled by voltage rather than current like a bipolar transistor. MOSFETs have a significantly higher switching speed than bipolar power transistors. Suitable for high power circuits, they generate almost no loss (little heat generation), enabling fast response, excellent linearity, and high efficiency. The positive temperature coefficient inhibits thermal runaway. (Degrades to an SFET - Smoke and Fire Emitting Transistor if subject to excessive voltages). See also IGBT . MSDS - Material Safety Data Sheet . Information provided by battery or cell manufacturers about any hazardous materials used in their products. Multiplexer - A multiplexer is a device which enables several communications links or signals to share a single communications channel. At the receiving end of the link a demultiplexer separates the signals again. Various coding schemes are possible which enable the signals to be transmitted simultaneously or sequentially. Nano - From the latin word meaning quotdwarfquot. One billionth or 10 -9. One micron 1000 nanometers. One nanometer is about the diameter of 3 to 6 atoms (depending on the element). Nanotechnology - Nanomaterials (nanocrystalline materials) are materials possessing grain sizes on the order of a billionth of a meter. Used for electrodes and separator plates in NiMH and Lithium ion batteries and also in supercapacitors. Their foam-like (aerogel) structure provides a very large effective surface area which can hold considerably more energy than their conventional counterparts. Nanobattery - Very small battery built using nano technology. Of microscopic size 1 micron diameter they deliver 3.5 volts. The electrodes are ceramic or carbon particles and the electrolyte is a solid polymer impregnated in an aluminium oxide membrane. Negative Delta V (NDV) - The NDV is the drop in the battery voltage which occurs when NiCad or NiMH cells reaches their fully charge state. Used to detect the end of the charging cycle in Nicads. Negative electrode - The electrode which has a negative potential. The anode. NEMA - The National Electric Manufacturers Association in the USA publish standards for batteries jointly with ANSI. (See above) Nernst equation - Used by cell designers to calculate the voltage of a chemical cell from the standard electrode potentials, the temperature and to the concentrations of the reactants and products. Neural Network - A powerful data modeling tool that is able to capture and represent complex inputoutput relationships. It is used as a basis for self learning systems. NIH - Not Invented Here. Used to describe engineers and managers who are reluctant to accept ideas from another organisation. Nominal capacity - Used to indicate the average capacity of a battery. It is the average capacity when batteries are discharged at 0.2C within one hour of being charged for 16 hours at 0.1C and 20plusmn 5degC. (or discharge at 0.05C for automotive batteries - SAE) Definition depends on the conditions. See Ampere Hours Ah above Nominal voltage - Used to indicate the voltage of a battery. Since most discharge curves are neither linear nor flat, a typical value is generally taken which is close to the voltage during actual use. NRE - Non-Recurring Engineering costs. A one time charge for design and implementation of custom battery packs or other products. NTC - A thermistor with a negative temperature coefficient, whose resistance decreases with increasing temperature. Nuclear fission - Occurs when the atomic nucleus splits into two or more smaller nuclei plus some by-products. These by-products include free neutrons and photons (usually gamma rays). Fission releases substantial amounts of energy (the nuclear binding energy ). The neutrons released by the fission process may collide with other nuclei causing them in turn to undergo fission initiating to a chain reaction. Nuclear fusion - A process in which two nuclei join together to form a larger nucleus and releasing energy. It takes considerable energy to overcome the repulsion between the two positively charged nuclei to force them to fuse. The fusion of lighter nuclei, which creates a heavier nucleus and a free neutron, will generally release even more energy than it took to force them together. It is an exothermic process which could produce self-sustaining reactions. Nuclear Magnetic Resonance (NMR) - The interaction of atomic nuclei placed in an external magnetic field with an applied electromagnetic field oscillating at a particular frequency. Magnetic conditions within the material are measured by monitoring the radiation absorbed and emitted by the atomic nuclei. Used in MRI scanners and as a spectroscopy technique to obtain physical, chemical, and electronic properties of molecules. OEM Original Equipment Manufacturer - A company with the prime responsibility for conceiving, designing, manufacturing and distributing a particular product line. Ohmic loss - The voltage drop across the cell during passage of current due to the internal resistance of the cell. Also known as IR loss or IR drop. Open circuit voltage OCV - The voltage of a cell or battery with no load attached measured with a voltmeter at room temperature. Operating voltage - Voltage between the two terminals of the battery with a load connected. Operational amplifier (Op amp) - A high gain DC amplifier with a voltage gain of 100 to 100,000 or more and a very high (ideally infinite) input impedance and very low (ideally zero) output impedance. Op-amps are the basic building block of linear integrated circuits used for analogue circuit applications. They have positive and negative inputs which allow circuits which use feedback to achieve a wide range of functions. Opportunity charging - Intermittent charging from sources whenever or wherever power is available. Opto-isolator - Also called opto-coupler . An isolation device using optical techniques (an LED transmitting across a small gap to a photocell) to isolate the electrical connections between a transmitter and a receiver. Used to pass signals between high voltage and low voltage circuits and to replace switches and relays. Having no electrical connection they also help to cut down on ground loops. Osmosis - The diffusion of a solvent through a semi permeable membrane from a region of low solute concentration to a region of high solute concentration. The semi permeable membrane is permeable to the solvent, but not to the solute, resulting in a chemical potential difference across the membrane which drives the diffusion. The solvent flows from the side of the membrane where the solution is weakest to the side where it is strongest to equalise the concentration on both sides. Over-charge - Continuous charging of the battery after it reaches full charge. Generally overcharging will have a harmful influence on the performance of the battery which could lead to unsafe conditions. It should therefore be avoided. Over-current - Exceeding the manufacturers recommended maximum discharge current for a cell or battery. Over-discharge - Discharging a battery below the end voltage or cut-off voltage specified for the battery. Overmoulding - An injection moulding technique used to encapsulate and protect components or small sub-assemblies, usually by moulding a soft, flexible, cosmetically attractive plastic over the components which must be able to withstand the temperatures and pressures of the moulding process. Used for cable connectors, gaskets, and for incorporating small components into cables. Two shot moulds may be used to provide soft plastic grips over a hard plastic shell. It provides rugged, almost unbreakable protection with built in strain relief. Over-voltage - The difference between the actual potential at which an electrochemical reaction occurs, and its theoretical equilibrium potential. Oxidation - The loss of electrons by a chemical species Packaging - In a battery, the mechanical structure used to contain and protect its components (cells, electronic circuits, contacts etc.). Parallel connection - The connection together of, two or more, similar cells to form a battery of higher capacity by connecting together all the cell terminals of the same polarity. Paramagnetism - The property of a substance which is attracted to a magnet. It is similar to ferromagnetism except that the attraction is weaker. When a paramagnetic material is placed in a strong magnetic field, it becomes a magnet as long as the strong magnetic field is present. But when the strong magnetic field is removed the magnetic effect is lost. Below the substances Curie temperature a paramagnetic material becomes ferromagnetic. Paramagnetism is exhibited by materials containing transition elements, rare earth elements and actinide elements. Liquid oxygen and aluminium are also examples of paramagnetic materials. See also Diamagnetism and Ferromagnetism . Passivation layer - A resistive layer that forms on the electrodes in some cells after prolonged storage impeding the chemical reaction. This barrier must be removed to enable proper operation of the cell. Applying chargedischarge cycles often helps in preparing the battery for use. In other applications, passivation is used as a method of shielding a metal surface from attack. Periodic Table of the Elements - A tabular display of the known chemical elements. The elements are arranged by electron structure so that many chemical properties vary regularly appearing in groups with common properties across the table. Each element is listed by its atomic number and chemical symbol. Permanent charge - The charging current which can safely be continuously supported by the battery, regardless of the state of the charge. Permeability (mu) - The measure of the characteristic of a medium to support the formation of a magnetic field. It indicates degree of magnetisation that a material obtains in response to an applied magnetic field. It is measured in units of Henries per metre (H m) Permittivity (epsilon) - The measure of the characteristic of a medium to resist the formation of an electric field. It gives an indication of how much electrical charge a material can store in a given volume. It is measured in units of Farads per metre (F m) Peukerts equation An empirical formula that approximates how the available capacity of a battery changes according to the rate of discharge. The equation shows that at higher currents, there is less available energy in the battery. Peukert number A value that indicates how well a battery performs under heavy currents. A value close to 1 indicates that the battery performs well the higher the number, the more capacity is lost when the battery is discharged at high currents. The Peukert number of a battery is determined empirically. pH - (potential (of) hydrogen) is a logarithmic measure of the concentration of hydrogen ions (H ) in a solution and, therefore, its acidity or alkalinity (basicity). pH - logH The pH scale extends from 0 to 14 (in aqueous solutions at room temperature). A pH value of 7 indicates a neutral (neither acidic nor basic) solution. A pH value of less than 7 indicates an acidic solution, the acidity increases with decreasing pH value. A pH value of more than 7 indicates an alkaline or basic solution, the alkalinity or basicity increases with increasing pH value. Photovoltaic cell - A device that directly converts the energy in light into electrical energy. Also called a photocell, a solar cell or a PV cell. Photovoltaic effect - The generation of an electromotive force as a consequence of the absorption of radiation. In practice a current which flows across the junction of two dissimilar materials when light falls upon it. Pilot Cell - A selected cell whose condition is assumed to indicate the condition of the entire battery. Plates - The electrodes used in a flat plate cell. PNGV - P artnership for a N ew G eneration of V ehicles. A partnership between government, industry and academia in the USA to improve all aspects of automotive design in which batteries figure highly. Polarisation - The change in the potential of a cell or electrode from its equilibrium value caused by the passage of an electric current through it. There are two irreversible electrochemical components, the quotelectrode polarisationquot at the electrodes and the quotconcentration polarisationquot in the electrolytic phase plus an ohmic loss component due to the electrical resistance of the cell. Also due to the build up of gas bubbles on the electrodes. Polarity reversal - Reversal of the polarity of a battery or cell due to over discharge. Polymer - Strictly it is a substance made of long repeating chains of molecules called monomers which may be identical or different. The term polymer is often used in place of plastic, rubber or elastomer. In battery technology polymer usually refers to a solid (plastic) ionic conductor that is an electrical insulator but passes ions. (See also Conducting Polymer above) Polymorphism - The ability of solid materials or compounds with the same chemical composition to exist in more than one form or crystal structure giving rise to materials with different physical or chemical properties. When the material consists of a single element, the property is known as allotropy . Positive electrode - The electrode which has a positive potential. The cathode. Electric current from this electrode flows into the external circuit. Pouch cell - A battery or cell contained in a flexible metal foil pouch. Power density - The amount of power available from a battery. It is expressed as the power available per unit volume or per unit weight (WL or Wkg). PowerNet - The standard proposed for next generation of automotive batteries. Nominally 42 Volt systems. Power transistor - A high current, bipolar transistor controlled by the current through the gate. Used in linear (series) regulators as the voltage dropper between the unregulated voltage input and the regulated output. Also used as a high current switching device in control and protection circuits. Needs a high current to turn it on and is slow to turn off and its negative temperature coefficient makes it prone to thermal runaway. For these reasons it was mostly superceded by MOSFET s in high power battery switching applications. See also Thyristor and IGBT . ppm - Parts Per Million Precursor - A chemical compound that participates in a chemical reaction which produces another compound. Prismatic cell - A slim rectangular sealed cell in a metal case. The positive and negative plates are stacked usually in a rectangular shape rather than rolled in a spiral as done in a cylindrical cell. Progressive dies - Multi-stage stamping tools for producing complex metal components from flat metal strip in a hydraulic or eccentric press. The die consists of two or more stages each of which carries out punching, drawing or folding operations with each down stroke of the press. Between each stroke, the strip moves from stage to stage through the die. Complex profiles and three dimensional shapes can be built up from a series of simpler operations which take place progressively at each stage as the strip passes through the die. Protection - A facility incorporated into battery packs to protect the cells from out of tolerance working conditions or misuse. PTC - A thermistor with a positive temperature coefficient, whose resistance increases with temperature. PPTC - A Polymeric Positive Temperature Coefficient device. It is a non-linear thermistor, more commonly called a resettable fuse . Pulse charger - Versatile, hybrid charger having some of the advantages of both switch-mode and linear chargers. More costly than both. Pulse discharge - A high rate discharge, usually of 1 second or less. Quick charge - Charging in three to six hours at about 0.3C rate. Needs special charger. Quiescent current - The current which continues to be drawn from the battery when the application it powers is in standby or hibernation mode. Ragone Plot - The graphical illustration of the specific energy of a cell as a function of its specific power. RAM cells - Rechargeable Alkaline Manganese cells. RAPS - Remote-Area Power Supplies - Power systems deriving their energy from local solar or wind sources using a battery for energy storage and supplying the load through DC-DC converters or AC inverters. Rare earth elements - The rare earth metals belong to group 3 of the periodic table in two blocks, the Lanthanide series and the Actinide series. Originally found in small quantities they are not particularly rare. They are silver, silvery-white, or grey metals with a high electrical conductivity and a bright lustre which tarnishes readily in air. Rate - When applied to cells it usually means the cells current carrying capacity. Rated capacity - The specified capacity of a battery. Reconditioning - One or more deep discharges below 1.0 Vcell with a very low controlled current, causing a change to the molecular structure of the cell and a rebuilding of its chemical composition. Reconditioning helps break down large crystals to a more desirable small size, often restoring the battery to its full capacity. Applies to nickel-based batteries. See also refurbishment (below) Recombinant system - Sealed secondary cells in which gaseous products of the electrochemical charging cycle are made to recombine to recover the active chemicals. A closed cycle system preventing loss of active chemicals. Used in Nicads and SLA batteries. Recovery - The lowering of the polarization of a cell during rest periods. Recycling - Reclamation of materials without endangering human health and the environment. Redox - A contraction of the words quotreductionquot and quotoxidationquot. The two chemical reactions on which cell chemistries depend. Redox Battery - A battery in which the chemical energy is stored in two dissolved ionic reactants separated by a membrane. Reduction - The gain of electrons by a chemical species. Refurbishing - The repair of worn out or damaged batteries. This is not the same as reconditioning (see above). Regenerative braking - This uses the electrical drive motor in an electric vehicle to act as a generator returning energy to the battery when overdriven mechanically by the vehicle wheels. This provides a powerful braking effect and at the same time captures energy which would otherwise be wasted or dissipated in the brakes. Relay - A mechanical switch operated by a solenoid. Resealable safety vent - The resealable vent internal to a cell to release excessive internal pressure . Reserve battery - Batteries which are stored in an inactive state without their electrolyte. They are only activated when needed by the introduction of the electrolyte. See also Water-activated batteries and Ampoule batteries. Reserve capacity - The number of minutes at which the battery can be discharged at 25 Amps and maintain a terminal voltage higher than 1.75 volts per cell, on a new, fully charged battery at 80degrees Fahrenheit (27 degC). Defines a batterys ability to power a vehicle with an inoperative alternator or fan belt. Used for comparing automotive SLI batteries . Resettable fuse - A fuse which protects against excessive current and temperature by interrupting the flow of current. After opening it will reset after the fault conditions have been removed but only after it has cooled. It requires no manual resetting or replacement. The quotPolyswitchquot is an example of this. R esidual Circuit Breaker ( RCCB ), or Residual Current Device ( RCD) - an electrical safety device which interrupts a circuit whenever it detects that the current is not balanced between the live (high voltage) conductor and the return neutral conductor. It can be used as a safety device by cutting off the supply voltage when it detects current leakage through the body of a person who is earthed (grounded) accidentally touching a live part of the circuit. See also Ground Fault Interruptor Earth Leakage Trip . Resistance welding - Resistance welding is a process used to join metallic parts with electric current. There are several forms of resistance welding, including spot welding, seam welding, projection welding, and butt welding. Rest periods - Interruptions to the charging process to allow the chemical reactions in the battery to stabilise. Reversible reaction - A chemical reaction which can be reversed to reconstitute the original components. RFI - Radio Frequency Interference. Transmittedemitted RFI affects other external equipment. Susceptibility measures the immunity of equipment from received RFI. See also EMC and Electromagnetic Radiation RFID - Radio Frequency Identification. Small tags incorporating a radio transmitter which can be used to identify or track items of value. RS232 connection - A standard for serial transmission of data between two devices. RS485 connection - A standard for serial transmission of data between multiple devices. SAE - Society of Automotive Engineers. The SAE Technical Standards Board issues and recommends industry standards. See also Standards Safety vent - A safety mechanism that is activated when the internal gas pressure rises above a normal level. Sampling Rate - The repetition frequency at which digital samples are taken of an analogue quantity. Sealed cells - A cell which remains closed and does not release gas or liquid when operated within the limits of charge and temperature specified by the manufacturer. An essential component in recombinant cells. Secondary battery - A battery which can be recharged and used repeatedly. Self-discharge - Capacity loss during storage due to the internal current leakage between the positive and negative plates. SEM (Scanning Electron Microscope) - Apparatus used to investigate the physical structure of cell components and surfaces. They typically cost about 500,000 or more. Semiconductor - An insulator whose conductivity can be manipulated by the addition of impurities ( doping ), by introduction of an electric field, by exposure to light. or by other means. Separator - A non-conductive semi-permeable film or grid to separate 2 electrodes to prevent them from contacting each other and short-circuiting but which allows the passage of ions through it. Series connection - The connection of, two or more, similar cells in a chain to form a battery of higher voltage by connecting the positive terminal of each cell to the to negative terminal of the next cell. Series regulator - Another name for a Linear regulator Service life - The period of useful life of a battery before a predetermined end point is reached. Shaft encoder - An electro-mechanical or optical device which converts the angular position or motion of a shaft or axle to an analogue or digital electrical signal. Also called a rotary encoder. Shedding - The loss of material from the plates of Lead Acid batteries. Shelf life - The duration a cell can be kept in storage and still retain its ability to give a specified performance. See also Battery Storage Shrouded terminals - Terminals surrounded by an insulating shroud which prevents accidental contact with the terminal. Shunt - A device which allows electric current to pass around another point in the circuit. Shunt regulator - A voltage regulator which uses a transistor or FET, in parallel with the load, which shorts out the excess voltage when the applied input voltage exceeds a specified limit producing a regulated output voltage. It is a simple but lossy design. Sintering - Heating a mixture of powdered metals, sometimes under pressure, to the melting-point of the metal in the mixture which has the lowest melting-point, the melted metal binding together the harder particles. SLA Battery - Sealed Lead Acid battery. In sealed batteries the generated oxygen combines chemically with the lead and then the hydrogen at the negative electrode, and then again with reactive agents in the electrolyte, to recreate water. A recombinant system. The net result is no significant loss of water from the cell. See also Flooded Lead Acid cell. SLA - Equipment used for rapid prototyping. See StereoLithography Apparatus below. SLI Battery - Common automotive battery used for Starting Lighting and Ignition Slow charge - Charging overnight in 14 to 16 hours at about 0.1C rate. Safe and simple. Smart Battery - An intelligent battery which contains information about its specification, its status and its usage profile which can be read by its charger or the application in which it is used. SMBus - System Management Bus. A two wire, 100 KHz, serial bus for interconnecting Smart Batteries which have built in intelligence, with their associated chargers or applications. Solar cell - A photovoltaic cell. Solar cells convert sunlight energy into electric current. They do not store energy. Solar panel - An array of photocells providing an increased output. Solenoid - A coil containing an iron plunger which moves when a current is passed through the coil. Solid State Battery - Cells with solid electrolytes. Lithium polymer cells are examples of this technology SOC - State of Charge. See below. SOH - State of Health. See below. Specific Energy - Same as Gravimetric Energy Density (WhKg) Specific Gravity SG - The ratio of the weight of a solution compared with the weight of an equal volume of water at a specified temperature. It is used to determine the charge condition in lead acid batteries. Specific Power - Same as Gravimetric Power Density (WKg) Spintronics - A technology used in solid state devices which exploits the intrinsic spin of the electron and its associated magnetic moment, in addition to its fundamental electronic charge. Also known as magnetoelectronics. Spiral Wound - Battery construction in which the electrodes with the electrolyte and separator between them are rolled into a spiral like a jelly roll (Swiss roll). Standard charge - The normal C10 charge used to recharge a cell or battery in 10 hours. Other definitions (charging periods) also apply. Standby power - A fully charged battery ready to take over supplying a load in case of emergency. Standby state - A state in which the main functions of a circuit have been powered down to save energy, but power remains applied to the circuit ready to make a rapid restart. (See also Hibernation state above) State of Charge - SOC - The available capacity of a battery expressed as a percentage of its rated capacity. State of Health - SOH - A measurement that reflects the general condition of a battery and its ability to deliver the specified performance compared with a fresh battery. It takes into account such factors as charge acceptance, internal resistance, voltage and self-discharge. It is not as precise as the SOC determination. Stereolithography (SLA) - A Rapid Prototyping (RP) system for creating plastic parts directly from 3D CAD files. The RP model speeds design validation and is also finds use as a master pattern. Stoichiometry - The branch of chemistry that deals with the numerical proportions in which substances react. Storage life - The length of time a cell or battery can be stored on open circuit without permanent deterioration of its performance. See also Battery Storage Studs - Threaded bolt connectors used on high power cells Sulphation - Growth of lead sulphate crystals in Lead-Acid batteries which inhibits current flow. Sulphation is caused by storage at low state of charge. Supercapacitor - A capacitor that can store a large amount of energy. Also called Ultracapacitor or Booster capacitor. Superconductivity - A phenomenon occurring below a very low, characteristic critical temperature in certain materials (superconductors), characterised by the complete absence of electrical resistance and the damping of the interior magnetic field (the Meissner effect ). Superconductors can carry currents that will not decay. Swelling - Distortion of cells caused by expansion of the active chemicals due to temperature and pressure effects. Switcher - A switch mode regulator. Switch mode charger - Charger which uses a switch mode regulator. More efficient but more costly than a Linear charger . Switch mode regulator - A switching regulator is a voltage regulator which uses an output stage, switched repetitively on and off, together with energy storage components (capacitors and inductors) to generate a DC output voltage. Regulation is achieved through Pulse Width Modulation (PWM). Output voltages can be generated that are greater than or less than the input voltage, and multiple output voltages can be generated with a single regulator. Tabs - Flat connectors used on pouch cells. Tafel equation - The relationship between the internal electrode potentials in a battery and the current which flows. This is an exponential relationship based on empirical results which quantifies the elecrochemical reactions. It is analogous to the Arrhenius equation which quantifies the thermochemical process relating the temperature to the rate at which a chemical action progresses. Taper charge - In quick chargers the charging current is is progressively reduced in a controlled way by controlling the supply voltage. In slow chargers the voltage is fixed and the charging current reduces in an uncontrolled way due to increase in the cell voltage as the charge builds up. Temperature cut-off - A temperature sensing method which detects heat rise in a cell at overcharge and switches the charger off or to a lower rate of charge. Temperature sensor - An electronic device which provides a voltage analogue of the temperature of the surface on which it is mounted. A thermistor is an example. Termination voltage - The maximum voltage which can be tolerated by a cell during charging without damaging the cell. The cell voltage at which the charging process should be terminated. Tesla (T) - The unit of magnetic flux density. 1 Tesla 1 Weber metre 2 Thermal Capacity - The amount of energy required to raise the temperature of an object by one degree Celsius. Expressed in JoulesKg. Thermal fuse - A safety device which interrupts a circuit when it detects excessive temperature. Thermal imaging - A photographic technique which displays the range of temperatures of a warm body in the form of a colour spectrum. Used as a design verification tool for detecting hot spots in battery and other equipment designs. Thermal management - The means by which a battery is maintained within its operating temperature limits during charging and discharging. Thermal runaway - A condition in which an electrochemical cell will overheat and destroy itself through internal heat generation. This may be caused by overcharge or high current discharge and other abusive conditions. Thermistor - An electrical device whose resistance varies with temperature. They are used as temperature-measuring devices or in electrical circuits to compensate for temperature variations of other components. Thyristor - Also called a Silicon-Controlled Rectifier or SCR . it is a solid-state high current semiconductor switching device similar to a diode, with an extra terminal which is used to turn it on. Once turned on, the thyristor will remain on (conducting) as long as there is a significant current flowing through it. If the current falls to zero, the device switches off. See also Power transistor . Traction battery - A high power deep cycle secondary battery designed to power electric vehicles or heavy mobile equipment. Transient response - The ability of an electrical or other device to respond faithfully to sudden changes to the input conditions. Trickle charge - A continuous charge at low rate, balancing losses through local action andor periodic discharge, to maintain a cell or battery in a fully charged condition. Normally at a C20 to C30 rate. TUumlV - TUumlV Rheinland Group (TUV - Technical Inspection Association) is an international service company which documents the safety and quality of new and existing products, systems and services. UL - Underwriters Laboratories Inc - (UL) is an independent, not-for-profit product safety testing and certification organization based in the USA. UL marking indicates that the product conforms with the safety standards laid down by Underwriters Laboratories. Ultrasonic welding - Ultrasonic welding involves the use of high frequency sound energy to soften or melt the thermoplastic at the joint. Parts to be joined are held together under pressure and are then subjected to ultrasonic vibrations usually at a frequency of 20, 30 or 40kHz. UPS - Uninterruptible Power Supply USABC - The United States Advanced Battery Consortium Valence - The combining capacity of an atom expressed as the number of single bonds the atom can form or the number of electrons an element gives up or accepts when reacting to form a compound. Venting - The release of excessive internal pressure from a cell in a manner intended by design to preclude explosion. Voltage cutoff - A voltage sensing device which will end a charge or discharge at a preset voltage value. Voltage limit - A voltage value a battery is not permitted to rise above on charge andor fall below on discharge Voltage regulator - A circuit which provides a fixed or controlled voltage output from a variable voltage input. Used in power supplies and chargers. Switching regulators. Linear regulators and Shunt regulators are the most common types. Voltaic efficiency - The ratio (expressed as a percentage) between the voltage necessary to charge a secondary cell and the corresponding discharge voltage. Volumetric Energy Density (WhL) - The energy output per unit volume of a battery Volumetric Power Density (WL) - The power output per unit volume of a battery VRLA battery - Valve Regulated Lead Acid Battery Ward-Leonard controller - A motor-generator system which uses a AC motor driving a variable voltage DC generator which drives a DC motor to provide a variable power transmission. Used for high power load testing. Watt - A unit of power, the rate of doing work. Watts Amps X Volts One Joule per second. WattHours (Wh) - A measure of the energy capacity of a battery. The amount of work done in one hour. 1 Wh 3.6 kJ. Weber (Wb) - The unit of the magniude of the magnetic flux. A flux density of one Wbm 2 (1 Weber per square meter) is 1 Tesla Well to wheel efficiency - The ratio between the mechanical energy ultimately delivered to the road wheels of a vehicle and the chemical energy content of the oil consumed in providing it. It is used to compare the fuel efficiencies of different methods of powering road vehicles and takes into account the refining process, the energy loss in the distribution process (in the case of hydrogen, the energy used to compress it) and the conversion efficiency of the vehicles power unit. See Well to Wheel Comparison Table Wet Cell - A cell with free flowing liquid electrolyte. X-ray Crystallography - The use of the property of X-ray diffraction by crystals to determine their physical structure. Zapping - A desperation measure to revive a shorted cell suffering from dendrites. A very high current, low voltage pulse from a large capacitor used in an attempt to vaporise the dendrites. Zebra battery - A high temperature Sodium Nickel Chloride battery delivering high power. If you have any questions, suggestions or comments about these pages please use t he Feedback Form to let us know. Thank you in advance for your interest.