Samlexpower SEC-1250UL Owner's Manual - Section 4 |
10 | SAMLEX AMERICA INC.
SAMLEX AMERICA INC. | 11
seCtIOn 4 |
Principle of Operation
StAGe 1- BUlK cHARGe StAGe (“i” PHASe)
InthisstageSEC-1250ULoutputsvoltageof13.5VDCandSEC-2425Aoutputs27V.
ThefollowingexplanationisforSEC-1250UL.ExplanationforSEC-2415ULwillbe
samebutthevoltagevalueswillbe2timesandcurrentvalueswillbehalfascompared
to SeC-1250UL.
note: For explanation purpose, it is assumed that the battery is deeply discharged
to around 10.5 / 21V when charging is initiated.
Whenthechargerisswitchedon,thebatterywilltrytodrawverylargecurrent=
(13.5V-10.5V)÷Internalresistance(0.02Ω)=150Awhichwillbemuchhigherthanthe
currentlimitvalueof50A.Thechargerwillentercurrentlimitcondition(pointA2),
itsinternalvoltagewilltrytodropbutwillbeclampedtotheterminalvoltageofthe
batteryi.e.10.5V(pointA1).Thebatterystartschargingatconstantcurrentof50A(Sec-
tionA2-B2)anditsintrinsicvoltagestartsrisingalmostlinearly(SectionA1-B1).When
itsintrinsicvoltageapproaches13.5V,thecurrentdrawnbythebatterywillreduceto
<50A.Atthispoint(B2),thechargerwillexitcurrentlimitandwilloutputaconstant
voltageof13.5V(pointB1).Asthebatterychargesfurtherunderconstantvoltageof
13.5V(SectionB1–C1),itsintrinsicvoltagerisesfurtheranditscurrentstartstotaper
down(SectionB2–C2).Thecurrenttapersdownbecausetheintrinsicbatteryvoltageis
risingandthedifferentialvoltagebetween13.5Vofthechargerandintrinsicvoltageof
thebatteryisreducingthereby,lessercurrentisdrivenintothebattery.Taperingcharge
isprovidedatthistransitiontoreducesurfacechargeeffecttoensurethatthecharge
slowlydiffusestotheinternalthicknessoftheplatesandpreventsovercharging.When
thechargingcurrenttapersdownto80%oftheratedcapacityofthecharger(40Afor
SEC-1250ULand20AforSEC-2425UL)atpoint“B2”,thechargertransitionstothenext
Stage2-AbsorptionBoostStage(“U
o
”Phase)
charging characteristics during this Stage Are As Follows:
• Batteryvoltagerisesslowlyandalmostlinearly(itwillstartrisingsharplyat
thebeginningofthenextAbsorptionStage2).
• TheentirechargingcurrentisusedtoconvertLeadSulfatetoSpongeLeadat
theNegativeplatesandtoLeadDioxideatthePositiveplates.
• Thereisnogassingandthechargingefficiencyishigh-around91%.
• Therestoredcapacityinthisstageisinverselyproportionaltothechargingrate
(duetoPeukertEffect).Thismeansthatasthechargingrateisincreased,the
capacityrestoredreduces.Thisstagerestores60%ofcapacityatchargingrate
ofC/5,70%to75%capacityatchargingrateofC/10and85%to90%of
capacityatchargingrateofC/20
• RedLEDmarked“IPhase”willbelitontheoptionalRemoteControl
Model900-RC