Battery & EV
Ah ↔ Wh
Convert amp-hours to watt-hours using battery voltage
V
Ah
Result
Energy capacity1200 Wh
In kilowatt-hours1,2 kWh
How does it work?
Amp-hours (Ah) measure the charge in a battery. A 100 Ah battery can theoretically supply 1 A for 100 hours, or 10 A for 10 hours.
Watt-hours (Wh) measure actual energy capacity: Wh = Ah × voltage (V). This is a more universal measure because it accounts for voltage differences.
For example: 100 Ah at 12 V = 1200 Wh = 1.2 kWh. But 100 Ah at 51.2 V (LiFePO₄) = 5120 Wh = 5.12 kWh — much more energy, same Ah rating.
Always compare battery energy capacity in Wh, not Ah, when batteries have different voltages.
Example
Example 1 (Ah → Wh): 200 Ah LiFePO₄ battery, 25.6 V nominal.
→ Energy: 200 × 25.6 = 5120 Wh = 5.12 kWh
Example 2 (Wh → Ah): E-bike battery 360 Wh, 36 V.
→ Capacity: 360 / 36 = 10 Ah
Assumptions
- •Uses nominal (rated) voltage, not charge or discharge end voltage
- •Actual usable energy is lower due to depth of discharge (DoD)
- •LiFePO₄ nominal cell voltage: 3.2 V → 12.8 V (4S), 25.6 V (8S), 51.2 V (16S)