Question 1

How is battery charge time calculated?

Accepted Answer

Charge time = battery capacity ÷ charge current × efficiency factor. A 2000 mAh battery charged at 1000 mA needs about 2 hours ideally; multiply by 1.2-1.5 for Li-ion and 1.4-1.65 for NiMH to account for charging losses.

Question 2

Why does charging take longer than the raw math?

Accepted Answer

No charging process is 100% efficient. Li-ion uses a constant-current/constant-voltage curve where the final 20% slows down. NiMH warms up and loses energy as heat. Lead-acid and LiFePO4 also have absorption stages. The efficiency factor models these losses.

Question 3

Should I use mAh, Ah or Wh?

Accepted Answer

mAh and Ah both work as long as your charger current uses the matching unit (mA with mAh, A with Ah). For Wh (watt-hours), enter it and a charger power in watts — the calculator converts automatically. Use one system consistently.

Question 4

What if the battery is partially charged?

Accepted Answer

Set the current charge percentage and the tool scales the remaining capacity accordingly — a 3000 mAh battery at 40% only needs about 60% of its capacity topped up, shortening the charge time proportionally.