280Ah to Wh — 3,360 Wh at 12V
280Ah stores 3,360 Wh at 12V, 6,720 Wh at 24V, and 13,440 Wh at 48V. Below: usable energy per chemistry, what it runs, and how the same energy is built from standard modules.
280Ah at 12V is 3,360 Wh — that is 3.36 kWh of nameplate energy.
Formula: Wh = Ah × V. The voltage is the nominal battery voltage, not the charging voltage.
A real LiFePO4 module of 280Ah is usually labelled 3,584 Wh, because its nominal voltage is 12.8V rather than a round 12V. Both 3,360 Wh and 3,584 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 | 280 Ah | 3,360 Wh | 3.36 |
| 24 V | 280 Ah | 6,720 Wh | 6.72 |
| 48 V | 280 Ah | 13,440 Wh | 13.44 |
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 % | 2,688 Wh | 224 Ah | ~3,500 |
| AGM | 50 % | 1,680 Wh | 140 Ah | ~600 |
| Gel | 50 % | 1,680 Wh | 140 Ah | ~800 |
| Flooded lead-acid | 50 % | 1,680 Wh | 140 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 | 179.2 h |
| 12V compressor fridge (average) | 45 W | 59.7 h |
| Diesel heater (fan and glow plug average) | 30 W | 89.6 h |
| Water pump (while running) | 65 W | 41.4 h |
| Laptop plus router | 75 W | 35.8 h |
| Kettle through an inverter | 1200 W | 2.2 h |
What this size is in practice
280Ah is not a retail battery, it is a cell size. Four prismatic 3.2V 280Ah cells in series make a 12V bank, eight make 24V, sixteen make 48V - the standard DIY LiFePO4 build. That is why 280Ah questions almost always come with a BMS question attached.
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 | 280 Ah | 3 x 100Ah / 12V |
| 24 V | 140 Ah | 3 x 100Ah / 12V |
| 48 V | 70 Ah | 3 x 100Ah / 12V |
Other capacities (Ah)
Other energy values (Wh)
FAQ
How many Wh is 280Ah?
280Ah is 3,360 Wh at 12V, 6,720 Wh at 24V, and 13,440 Wh at 48V. Multiply the amp-hours by the nominal battery voltage: Wh = Ah × V.
How much of that 3,360 Wh can I use?
On LiFePO4 at 80% depth of discharge you get 2,688 Wh (224 Ah at 12V). On AGM or gel at 50% you get 1,680 Wh (140 Ah). Same nameplate, very different usable energy.
How long does that run a 12V fridge?
A compressor fridge averaging 45 W runs about 59.7 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 3,584 Wh instead of 3,360 Wh?
Because LiFePO4 has a nominal voltage of 12.8V per 12V module, not exactly 12V. 280Ah × 12.8V = 3,584 Wh. The 12V figure of 3,360 Wh is the conservative system-voltage calculation. Both describe the same battery.
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