300Wh to Ah — 25 Ah at 12V
300 Wh is 25 Ah at 12V, 12.5 Ah at 24V, and 6.3 Ah at 48V. Below: usable energy per chemistry, what it runs, and which module count gets you there.
300 Wh at 12V is 25 Ah of battery capacity.
Formula: Ah = Wh ÷ V. Divide by the nominal battery voltage of the bank, not by the charger voltage.
Result
Energy in Wh equals capacity in Ah multiplied by battery voltage. 1000 Wh equals 1 kWh.
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Design Your SystemAt every system voltage
The same capacity stores four times the energy at 48V that it does at 12V, and draws a quarter of the current for the same load.
| System voltage | Capacity | Energy | kWh |
|---|---|---|---|
| 12 V | 25 Ah | 300 Wh | 0.3 |
| 24 V | 12.5 Ah | 300 Wh | 0.3 |
| 48 V | 6.3 Ah | 300 Wh | 0.3 |
How much of it you can actually use
Nameplate energy is not usable energy. Depth of discharge caps what you may take out before you damage the battery, and it differs by chemistry.
| Chemistry | Depth of discharge | Usable energy | Usable capacity | Cycles at that DoD |
|---|---|---|---|---|
| LiFePO4 | 80 % | 240 Wh | 20 Ah | ~3,500 |
| AGM | 50 % | 150 Wh | 12.5 Ah | ~600 |
| Gel | 50 % | 150 Wh | 12.5 Ah | ~800 |
| Flooded lead-acid | 50 % | 150 Wh | 12.5 Ah | ~400 |
What that runs
Runtime from the usable LiFePO4 energy at 12V (80% depth of discharge), one load at a time, no inverter losses on the DC rows.
| Load | Power | Runtime |
|---|---|---|
| LED lighting | 15 W | 16 h |
| 12V compressor fridge (average) | 45 W | 5.3 h |
| Diesel heater (fan and glow plug average) | 30 W | 8 h |
| Water pump (while running) | 65 W | 3.7 h |
| Laptop plus router | 75 W | 3.2 h |
| Kettle through an inverter | 1200 W | 0.2 h |
What this size is in practice
300Wh is the small power-station class - enough for phones, a laptop and a few LED hours, not enough for a compressor fridge overnight. As a 12V bank it is a 25Ah battery.
Building the same energy from standard modules
How many standard 100Ah 12V modules add up to this energy, and what capacity that becomes at each system voltage.
| System voltage | Capacity | Standard modules |
|---|---|---|
| 12 V | 25 Ah | 1 x 100Ah / 12V |
| 24 V | 12.5 Ah | 1 x 100Ah / 12V |
| 48 V | 6.3 Ah | 1 x 100Ah / 12V |
Other energy values (Wh)
Other capacities (Ah)
FAQ
How many Ah is 300 Wh?
300 Wh is 25 Ah at 12V, 12.5 Ah at 24V, and 6.3 Ah at 48V. Divide the watt-hours by the nominal battery voltage: Ah = Wh ÷ V.
How much of that 300 Wh can I use?
On LiFePO4 at 80% depth of discharge you get 240 Wh (20 Ah at 12V). On AGM or gel at 50% you get 150 Wh (12.5 Ah). Same nameplate, very different usable energy.
How long does that run a 12V fridge?
A compressor fridge averaging 45 W runs about 5.3 hours on the usable LiFePO4 energy at 12V. Cycling depends on ambient temperature, so treat this as the upper bound for a well-insulated unit.
What capacity is 300 Wh on a real LiFePO4 module?
At the true LiFePO4 nominal voltage of 12.8V, 300 Wh corresponds to 23.4 Ah. At a round 12V it is 25 Ah. Datasheets use 12.8V, most calculators use 12V.
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