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Editable example valuesYour estimate
Live calculationNo location or tariff is detected automatically. All results use the values you enter.
What is this tool used for?
Use this tool to estimate how long a battery takes to charge from its current level to a target level with a stated amount of charging power.
How to use this calculator
Enter nominal battery kWh, starting and target charge percentages, available charger input, charging efficiency and an allowance for taper or absorption. Available charging power should be the amount left after competing loads.
Understanding your results
The result shows the energy increase and estimated charging duration. It assumes a steady power source, with an adjustable extra-time allowance. Solar charging can take longer when cloud, darkness or other loads reduce available power.
How this is calculated
Before you use the result
Assumes constant charger input available after other loads. The extra-time allowance is editable, not a battery-specific charging curve. Actual charging depends on chemistry, temperature, BMS limits and absorption; solar-only charging may span multiple days.
What should I check before using this estimate?
Assumes constant charger input available after other loads. The extra-time allowance is editable, not a battery-specific charging curve. Actual charging depends on chemistry, temperature, BMS limits and absorption; solar-only charging may span multiple days.