Battery Charge Time Calculator
Estimate how long an e-bike or e-scooter takes to charge — from any state of charge to any target — using the pack capacity, charger current, and charging efficiency.
Estimated charge time
How the estimate works
Charging is filling amp-hours back into the pack. The amp-hours you need equal the capacity times the percentage you are adding; the charger delivers a fixed current measured in amps; and dividing one by the other gives hours. Because some energy is always lost as heat, the tool scales the time up by an efficiency figure.
Set the from and to percentages to model a real habit — a nightly top-up from 30% to 80% is much quicker than a full charge, and easier on the battery. The result is shown both as hours-and-minutes and as decimal hours.
Frequently Asked Questions
How is charge time estimated?
The charge you need to add is the pack's capacity multiplied by the gap between your starting and target state of charge. Dividing that by the charger's output current gives the time, and dividing again by the charging efficiency accounts for the energy lost as heat. A 10 Ah pack charged from empty at 2 A, at 90% efficiency, takes about 5 hours 33 minutes.
Why does a faster charger not cut the time proportionally at the end?
Lithium chargers charge at a constant current until the pack nears full, then switch to a constant-voltage phase where the current tapers off. This calculator models the constant-current part, so it slightly underestimates the last 10–20%. In practice the final stretch to 100% always takes longer than the linear estimate.
Is it better to charge to 100% every time?
For longevity, no. Lithium batteries age more slowly if you keep them between roughly 20% and 80% for everyday use and only charge to 100% before a long ride. This tool lets you set the from and to percentages so you can see how much time a partial top-up actually takes.
Should I use the charger that came with the vehicle?
Use a charger matched to your battery's voltage and chemistry — the supplied one, or a quality replacement of the same spec. A mismatched or low-quality charger can overheat the pack or degrade it faster, and the money saved is trivial next to the cost of a battery.
Educational estimate only. Real charge time depends on the charger's taper profile, battery temperature, and pack age. Never leave a charging battery unattended for long periods.