Charging
Charging Current Calculator
Get a typical charging current range for your battery capacity and chemistry.
Formula
I(min) = C × c(min)
I(max) = C × c(max)
flooded/EFB 0.10–0.20C · AGM 0.10–0.25C · GEL 0.10–0.20C · LiFePO4 0.20–0.50C (typical)Worked example
100 Ah flooded → 10–20 A typical charging current.
Limitations and warnings
- These are general industry ranges. The battery datasheet and the BMS limits (for lithium) always prevail.
Four values that are often confused
- Nominal capacity (Ah)
- Charge a battery delivers under rated conditions, usually over 20 hours (C20) at 25 °C.
- Usable capacity
- The part of the nominal capacity you can use without damaging the battery — about 50% for lead-acid, 80–90% for LiFePO4.
- Cranking current (CCA)
- Current deliverable for a short time in the cold to start an engine. It measures power, not stored charge, and cannot be converted to Ah.
- Stored energy (Wh)
- Ah × voltage. The right unit to compare batteries of different voltages.