Battery & DC Systems
Battery Charge Time
Calculate charge time for lead-acid, AGM and lithium batteries based on charger current and battery capacity.
Units:
Lead-acid charging: bulk phase (0-80%) at constant current, absorption phase (80-100%) at constant voltage. Full charge takes 1.2-1.5x the theoretical time. Never charge at more than C/5 for lead-acid.
t_charge = (C x DoD) / (I_charge x eta_charge)
Input
Battery capacity C iNominal battery capacity (C20 rate) in Ah.
Ah
Current depth of discharge iHow discharged the battery is. 100% = fully empty.
%
Charger current iConstant charge current. Max: C/10 for lead-acid, C/2 for LiFePO4.
A
Charge efficiency iCoulombic efficiency. Lead-acid: 80-90%, Li-ion: 95-99%.
%
Battery chemistry iChemistry affects charge algorithm and efficiency.
Result
Ah to restore [Ah]
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Theoretical charge time [h]
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Estimated actual time [h]
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Charge C-rate [C]
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Max recommended current [A]
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