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Supercapacitors – FM Series
Notes on Using Supercapacitors or Electric Double-Layer Capacitors (EDLCs)
1. Circuitry Design
1.1 Useful life
TheFCSeriesSupercapacitor(EDLC)usesanelectrolyteinasealedcontainer.Waterintheelectrolytecanevaporate
whileinuseoverlongperiodsoftimeathightemperatures,thusreducingelectrostaticcapacitywhichinturnwillcreate
greaterinternalresistance.Thecharacteristicsofthesupercapacitorcanvarygreatlydependingontheenvironmentin
whichitisused.Basicbreakdownmodeisanopenmodeduetoincreasedinternalresistance.
1.2Failrateintheeld
Basedonelddata,thefailrateiscalculatedatapproximately0.006Fit.Weestimatethatunreportedfailuresareten
timesthisamount.Therefore,weassumethatthefailrateisbelow0.06Fit.
1.3Exceedingmaximumusablevoltage
Performancemaybecompromisedandinsomecasesleakageordamagemayoccurifappliedvoltageexceeds
maximum working voltage.
1.4Useofcapacitorasasmoothingcapacitor(rippleabsorption)
Assupercapacitorscontainahighlevelofinternalresistance,theyarenotrecommendedforuseassmoothing
capacitorsinelectricalcircuits.Performancemaybecompromisedand,insomecases,leakageordamagemayoccurif
asupercapacitorisusedinrippleabsorption.
1.5 Series connections
Asappliedvoltagebalancetoeachsupercapacitorislostwhenusedinseriesconnection,excessvoltagemaybe
appliedtosomesupercapacitors,whichwillnotonlynegativelyaffectitsperformancebutmayalsocauseleakage
and/ordamage.Allowamplemarginformaximumvoltageorattachacircuitforapplyingequalvoltagetoeach
supercapacitor(partialpressureresistor/voltagedivider)whenusingsupercapacitorsinseriesconnection.Also,
arrangesupercapacitorssothatthetemperaturebetweeneachcapacitorwillnotvary.
1.6CasePolarity
Thesupercapacitorismanufacturedsothattheterminalontheoutercaseisnegative(-).Alignthe(-)symbolduring
use.Eventhoughdischarginghasbeencarriedoutpriortoshipping,anyresidualelectricalchargemaynegativelyaffect
other parts.
1.7 Use next to heat emitters
Usefullifeofthesupercapacitorwillbesignicantlyaffectedifusednearheatemittingitems(coils,powertransistors
andposistors,etc.)wherethesupercapacitoritselfmaybecomeheated.
1.8 Usage environment
Thisdevicecannotbeusedinanyacidic,alkalineorsimilartypeofenvironment.