Wh
watt-hour
Energyexact by definition
The watt-hour is one watt sustained for one hour, which is exactly 3600 joules since the hour is exactly 3600 seconds. The relation is exact. It is the natural unit for batteries and small energy stores, where a capacity in amp-hours multiplied by a voltage gives watt-hours directly.
Watch out: Battery capacity quoted in milliamp-hours is not an energy and cannot be compared across different voltages. A 3000 mAh cell at 3.7 V holds 11.1 Wh, while a 3000 mAh pack at 11.1 V holds 33.3 Wh. Only the watt-hour figure is comparable.
| 1 Wh | 3,600 J |
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