How Many Amp-Hours Do You Need for Van Life?
Amp-hours follow directly from two decisions: how much energy you use in a
day, and how many cloudy days you want the battery to cover on its own. The
formula is Ah = (daily Wh × days) ÷ depth of discharge ÷ system volts.
This table uses LiFePO4 at 80% depth of discharge on a 12V system. Move to
24V and every amp-hour figure roughly halves.
| Daily load | 1 day | 2 days | 3 days |
|---|---|---|---|
| 500 Wh | 53 Ah | 105 Ah | 157 Ah |
| 750 Wh | 79 Ah | 157 Ah | 235 Ah |
| 1,000 Wh | 105 Ah | 209 Ah | 313 Ah |
| 1,500 Wh | 157 Ah | 313 Ah | 469 Ah |
| 2,000 Wh | 209 Ah | 417 Ah | 625 Ah |
| 3,000 Wh | 313 Ah | 625 Ah | 938 Ah |
Most van builds land between 1,000 and 2,000 Wh a day, which is roughly a 200–400 Ah LiFePO4 bank for two days of autonomy. Two days is a sensible default: it covers a single overcast day without leaving you at zero. If you travel cloudy regions or park in shade, add a day; if you chase the sun and can move, one day may be enough.
Don't forget cold weather
Below freezing, usable LiFePO4 capacity drops by roughly 20%, so a cold-climate build should add about a fifth to these amp-hours — and remember lithium cannot be charged below 0 °C without a heater. The calculator applies this derate automatically when you check the cold-weather box.
Quick start with a profile:
Your daily loads
Add each device with its watts and hours per day.
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Solar array
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Add loads to size your array.
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Battery bank
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Charge controller (MPPT)
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Inverter
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Battery-to-inverter wire & fuse
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Estimated cost
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Budget street price → premium brands.