kWh to Ah Converter
Convert kilowatt-hours to amp-hours based on voltage. The formula is Ah = (kWh × 1000) ÷ Voltage. This conversion is essential for battery sizing, solar system design, and understanding battery capacity in relation to energy storage.
How to Convert kWh to Ah
- Determine the energy in kilowatt-hours (kWh).
- Multiply by 1000 to convert to watt-hours (Wh).
- Divide by the battery voltage to get amp-hours (Ah).
Formula
Ah = (kWh × 1000) ÷ Voltage
Ah = Wh ÷ V
Since kWh = kilo-watt-hours and Wh = V × Ah, we can derive Ah from kWh and voltage.
Example Calculation
1 kWh battery at 12V:
Ah = (1 × 1000) ÷ 12 = 83.33 Ah
A 13.5 kWh Tesla Powerwall at 48V:
Ah = (13.5 × 1000) ÷ 48 = 281.25 Ah
kWh to Ah Reference Table
| Energy (kWh) | At 12V | At 24V | At 48V |
|---|---|---|---|
| 0.5 kWh | 41.67 Ah | 20.83 Ah | 10.42 Ah |
| 1 kWh | 83.33 Ah | 41.67 Ah | 20.83 Ah |
| 2 kWh | 166.67 Ah | 83.33 Ah | 41.67 Ah |
| 3 kWh | 250.00 Ah | 125.00 Ah | 62.50 Ah |
| 5 kWh | 416.67 Ah | 208.33 Ah | 104.17 Ah |
| 10 kWh | 833.33 Ah | 416.67 Ah | 208.33 Ah |
| 13.5 kWh | 1,125.00 Ah | 562.50 Ah | 281.25 Ah |
| 20 kWh | 1,666.67 Ah | 833.33 Ah | 416.67 Ah |
Frequently Asked Questions
What is an amp-hour (Ah)?
An amp-hour is a unit of electric charge. A 100 Ah battery can deliver 1 amp for 100 hours, or 10 amps for 10 hours, or 100 amps for 1 hour (theoretically).
What is the difference between kWh and Ah?
kWh measures energy (power × time), while Ah measures charge (current × time). To convert between them, you need to know the voltage: kWh = Ah × V ÷ 1000.
How is battery capacity measured?
Small batteries (phones, laptops) use mAh. Larger batteries (cars, solar) use Ah. Energy storage systems often use kWh because it accounts for voltage differences.
Why does voltage matter for this conversion?
Higher voltage batteries store the same energy in fewer amp-hours. A 48V battery needs only 1/4 the Ah of a 12V battery to store the same kWh of energy.
How do I calculate battery runtime?
Runtime (hours) = Battery capacity (Ah) ÷ Load current (A). For example, a 100 Ah battery powering a 5A load lasts about 20 hours (less in practice due to efficiency losses).