100Ah to Wh — 1,200 Wh at 12V
100Ah stores 1,200 Wh at 12V, 2,400 Wh at 24V, and 4,800 Wh at 48V. Below: usable energy per chemistry, what it runs, and how the same energy is built from standard modules.
100Ah at 12V is 1,200 Wh — that is 1.2 kWh of nameplate energy.
Formula: Wh = Ah × V. The voltage is the nominal battery voltage, not the charging voltage.
A real LiFePO4 module of 100Ah is usually labelled 1,280 Wh, because its nominal voltage is 12.8V rather than a round 12V. Both 1,200 Wh and 1,280 Wh describe the same battery.
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 | 100 Ah | 2,400 Wh | 2.4 |
| 48 V | 100 Ah | 4,800 Wh | 4.8 |
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
100Ah is the reference size of the whole 12V world: the standard drop-in module, the capacity every build guide assumes, and the number nearly every "how much battery do I need" answer is expressed in. A single 12V 100Ah LiFePO4 stores 1,280Wh at its true 12.8V nominal voltage - the source of the constant confusion between 1,200Wh and 1,280Wh.
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 capacities (Ah)
Other energy values (Wh)
FAQ
How many Wh is 100Ah?
100Ah is 1,200 Wh at 12V, 2,400 Wh at 24V, and 4,800 Wh at 48V. Multiply the amp-hours by the nominal battery voltage: Wh = Ah × 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.
Why does the datasheet say 1,280 Wh instead of 1,200 Wh?
Because LiFePO4 has a nominal voltage of 12.8V per 12V module, not exactly 12V. 100Ah × 12.8V = 1,280 Wh. The 12V figure of 1,200 Wh is the conservative system-voltage calculation. Both describe the same battery.
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