Samlexpower SEC-1250UL Owner's Manual - Section 4 |
6 | SAMLEX AMERICA INC.
SAMLEX AMERICA INC. | 7
seCtIOn 4 |
Principle of Operation
i
inFo
Forcompleteunderstandingofworkingofbatterychargers,understandingof
operationofLeadAcidbatteriesisdesirable.
Fordetailedinformationonconstruction,workingandapplicationofbatteries,
pleaserefertoApplicationNotetitled“LeadAcidBatteries–Constructionand
Application”atthefollowinglinktoSamlexAmerica,Inc.website:
www.samlexamerica.com/support/application_notes.aspx
BAtteRy cHARGeR iS A cURRent liMited dc PoWeR SUPPly
ThechargerisacurrentlimitedDCpowersupplythatconverts120/230VAC,50/60Hz
toregulatedDCvoltagesandlimitsthemaximumoutputcurrentasfollows:
Model no.
current limit
constant
Voltage at Bulk
Stage “i”
constant
Voltage at
Absorption
Stage “U
0
”
constant
Voltage at
Float Stage
“U”
SeC-1250UL
50A
13.5VDC
14.0VDCor
14.4VDC
13.5VDC
SeC-2425UL
25A
27VDC
28.0VDCor
28.8VDC
27VDC
Thespecifiedoutputvoltageofthechargerduringparticularchargingstageisheld
constanttillthecurrentlimitvalueisreached.WhenthebatteryorDCloadtriestodraw
current>thecurrentlimitvalue,thechargerlimitsthecurrenttothecurrentlimitvalue
andtheoutputvoltageofthechargerdropsandisnolongerconstant.Whenthechar-
gerisconnectedtoabatteryandisincurrentlimitcondition,theterminalvoltageof
thechargerwillbeclampedtotheactuallowerintrinsicterminalvoltageofthebattery
(assumingthechargerisveryclosetothebatteryandthereisnovoltagedropinthe
wiresconnectionthechargertothebatteries).
BAtteRy iMPedAnce And cHARGinG cURRent
Theinternalimpedanceofahealthybatteryisverylow-intensofmilliOhms(The
impedance is higher in discharged condition due to Lead Sulfate formation and reduces
whenthebatteryisfullycharged–LeadSulfategetsfullyconvertedtoLeadandLead
Dioxide).Averageimpedancemaybeassumedas20milliOhmor0.02Ohm
Whenthechargerisdeliveringaconstantvoltage(isnotincurrentlimitcondition),the
charging current drawn by the battery can be roughly calculated as follows:
charging current = (charger Voltage - intrinsic battery voltage) ÷ internal resistance (0.02 ohm)