Charging-Time Calculator
Estimate general battery charge time from capacity, charger current, starting state of charge, target state of charge, and efficiency. This is not an EV charger database.
Advanced energy and taper considerations
For an energy-based estimate, capacity in watt-hours divided by charger power in watts gives ideal hours. Real constant-current/constant-voltage charging tapers near the target; battery voltage, chemistry, thermal limits, charger protocol, and a taper factor can all make actual time longer.
Charging-time formula
Required capacity = battery capacity × (target SOC − starting SOC). Estimated time = required capacity ÷ charger current ÷ efficiency, where efficiency is a decimal. The page converts percentage efficiency to that decimal internally.
Worked example
A 10 Ah battery moving from 20% to 80% requires 6 Ah. At 2 A and 85% efficiency, the estimate is about 3.53 hours, or 3 hours 32 minutes.
Assumptions and safety
- Capacity and current use matching units: Ah with A, or mAh with mA.
- The model assumes a steady effective current and does not model thermal cutback.
- Use the battery and charger manufacturer's limits; do not use this estimate as a charging safety control.