When you need this conversion
Portable power stations, solar generators, and lithium packs are usually rated in watt-hours (Wh), but wiring, fuses, charge controllers, and older 12 V equipment are specified in amps or amp-hours. Converting Wh to Ah lets you check whether a battery can deliver enough current, size a fuse or breaker correctly, or compare a lithium power station against a traditional lead-acid bank.
The formula in plain terms
Amp-hours equal watt-hours divided by voltage: Ah = Wh divided by V. This is the inverse of the Ah-to-Wh formula and follows directly from power equals current times voltage. Always use the nominal voltage of the specific battery or system, since a 12 V battery and a 48 V battery holding the same Wh have very different Ah ratings.
Common Wh to Ah values
| Wh | at 12 V | at 24 V | at 48 V |
|---|---|---|---|
| 500 Wh | 41.7 Ah | 20.8 Ah | 10.4 Ah |
| 1,000 Wh | 83.3 Ah | 41.7 Ah | 20.8 Ah |
| 2,000 Wh | 166.7 Ah | 83.3 Ah | 41.7 Ah |
Practical tips
Match voltage to the actual output
Many portable power stations step voltage up or down internally, so the Ah rating only makes sense at the specific output voltage you plan to use, such as a 12 V accessory port.
Use Ah for wiring and fuse sizing
Once you know the Ah or peak amp draw, you can size wiring and fuses correctly using a wire size calculator, since undersized cable on a high-current 12 V or 24 V circuit is a common fire risk in solar setups.
Remember usable capacity is lower than rated capacity
The Ah figure from this formula reflects total nominal capacity. Real-world usable capacity is reduced by depth-of-discharge limits and inverter or converter losses, so build in a safety margin when sizing a system around a target runtime.