1200Wh to Ah — 100 Ah at 12V
1200 Wh is 100 Ah at 12V, 50 Ah at 24V, and 25 Ah at 48V. Below: usable energy per chemistry, what it runs, and which module count gets you there.
1200 Wh at 12V is 100 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 | 100 Ah | 1,200 Wh | 1.2 |
| 24 V | 50 Ah | 1,200 Wh | 1.2 |
| 48 V | 25 Ah | 1,200 Wh | 1.2 |
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 % | 960 Wh | 80 Ah | ~3,500 |
| AGM | 50 % | 600 Wh | 50 Ah | ~600 |
| Gel | 50 % | 600 Wh | 50 Ah | ~800 |
| Flooded lead-acid | 50 % | 600 Wh | 50 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 | 64 h |
| 12V compressor fridge (average) | 45 W | 21.3 h |
| Diesel heater (fan and glow plug average) | 30 W | 32 h |
| Water pump (while running) | 65 W | 14.8 h |
| Laptop plus router | 75 W | 12.8 h |
| Kettle through an inverter | 1200 W | 0.8 h |
What this size is in practice
1200Wh is 12V x 100Ah - the textbook result every conversion guide quotes. Real LiFePO4 modules of the same 100Ah are labelled 1280Wh because their nominal voltage is 12.8V, not 12V.
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 | 100 Ah | 1 x 100Ah / 12V |
| 24 V | 50 Ah | 1 x 100Ah / 12V |
| 48 V | 25 Ah | 1 x 100Ah / 12V |
Other energy values (Wh)
Other capacities (Ah)
FAQ
How many Ah is 1200 Wh?
1200 Wh is 100 Ah at 12V, 50 Ah at 24V, and 25 Ah at 48V. Divide the watt-hours by the nominal battery voltage: Ah = Wh ÷ V.
How much of that 1,200 Wh can I use?
On LiFePO4 at 80% depth of discharge you get 960 Wh (80 Ah at 12V). On AGM or gel at 50% you get 600 Wh (50 Ah). Same nameplate, very different usable energy.
How long does that run a 12V fridge?
A compressor fridge averaging 45 W runs about 21.3 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 1200 Wh on a real LiFePO4 module?
At the true LiFePO4 nominal voltage of 12.8V, 1200 Wh corresponds to 93.8 Ah. At a round 12V it is 100 Ah. Datasheets use 12.8V, most calculators use 12V.
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