Battery Charging Time Calculator
Estimate charging time from battery capacity, state of charge and charger current.
About Battery Charging Time Calculator
Charging is efficient and fast up to about 80 per cent state of charge, after which the charger tapers current to avoid overvoltage. The last 20 per cent therefore takes disproportionately longer than the bulk phase. Quoting a full-charge time is misleading for most chemistries; the bulk phase to 80 per cent is the figure that matters in practice.
Formula
Battery Charging Time
Time = capacity × ΔSoC ÷ (charge current × efficiency)
- ΔSoC
- Change in state of charge as a fraction
- bulk phase
- Constant-current stage up to about 80%, after which current tapers
Worked example
With the default values below, Battery Charging Time Calculator returns Charging Time of 4.546. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Battery capacityminimum 0 Ah
- 100 Ah
- Starting state of chargeaccepts 0–100 %
- 20 %
- Target state of chargeaccepts 0–100 %
- 100 %
- Charger currentminimum 0.01 A
- 20 A
- Charging efficiencyaccepts 0–100 %
- 88 %
Results
- Charging Time
- 4.546 h
- Charging Time
- 272.7 min
- Charge to Replace
- 80.00 Ah
- Bulk Phase to 80%
- 3.409 h
- Effective C-Rate
- 0.2000 C
Step by step
- 1Values used
- 2Battery Charging Time
- 3Charging Time= 4.546 h
- 4Charging Time= 272.7 min
- 5Charge to Replace= 80.00 Ah
- 6Bulk Phase to 80%= 3.409 h
- 7Effective C-Rate= 0.2000 C
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax or compounding frequency into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Battery Charging Time calculated?
Time = capacity × ΔSoC ÷ (charge current × efficiency) Charging is efficient and fast up to about 80 per cent state of charge, after which the charger tapers current to avoid overvoltage. The last 20 per cent therefore takes disproportionately longer than the bulk phase.
Why does Battery Charging Time matter?
Quoting a full-charge time is misleading for most chemistries; the bulk phase to 80 per cent is the figure that matters in practice.
What values do I need to enter?
This calculator takes 5 inputs: Battery capacity, Starting state of charge, Target state of charge, Charger current, Charging efficiency. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.