Battery Capacity Calculator

Your details

The rated capacity printed on the battery or in the device spec sheet.
Nominal voltage of the battery (e.g. 3.7 V for Li-ion, 12 V for lead-acid).
V
Affects the safe discharge reserve and charging efficiency used in runtime and charge-time calculations.
Average current the device draws during use. Check your device spec sheet or measure with a USB tester.
Output current of the charger. Printed on the charger adapter (e.g. 5V/2A means 2000 mA).
How full the battery is now, as a percentage. Use 0 if starting from empty.
%
Average retail electricity rate in your area. Global average is about $0.14-$0.16 per kWh.
per kWh
Energy storedSmall portable battery
18.5Wh

Total energy the battery holds at nominal voltage

Capacity5Ah
Usable energy14.8Wh
Battery runtime8h
Runtime (h : min)8 h 0 min
Charge time5.05h
Charge time (h : min)5 h 3 min
C-rate0.1C
Cost per full charge0.003
0.1 C
Very light (low heat, long life)<0.5Normal discharge0.5-1Moderate load1-2High load (check spec)2+
Total energy (Wh)18.5
Usable energy (Wh)14.8

18.5 Wh stored, 14.8 Wh usable.

  • This battery stores 18.50 Wh of energy total, with 14.80 Wh usable after the 20% reserve for li-ion.
  • At the load you entered, the battery runs for about 8 h 0 min.
  • With your charger, a full charge takes about 5 h 3 min.
  • Each full charge costs about $0.0030 at your electricity rate.

Next stepYour C-rate of 0.10C is low, which is easy on the battery and maximises cycle count.

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