LiFePO4 vs AGM for Van Life: Which and What Size
The difference between LiFePO4 and AGM is not just price — it is how much of the battery you can actually use. LiFePO4 gives you about 80% of its rated capacity every cycle; AGM gives you about 50% before you start shortening its life. That means an AGM bank has to be far larger to deliver the same usable energy. Here is the same 1,000 Wh/day, 2-day build sized both ways.
| Spec | LiFePO4 | AGM |
|---|---|---|
| Usable depth of discharge | 80% | 50% |
| Usable capacity needed | 2,500 Wh | 4,000 Wh |
| Battery size at 12V | 209 Ah | 334 Ah |
| Rough bank weight | ~54 lb | ~210 lb |
| Typical cycle life | 3,000–5,000 | 300–500 |
| Charge below 0 °C | No (needs heater) | Yes (slowly) |
| Up-front cost/kWh usable | $200–$700 | $150–$350 |
The AGM bank needs 334 Ah against LiFePO4's 209 Ah — about 1.6× the amp-hours and roughly 4× the weight — to do the same job. AGM also lasts a tenth as many cycles, so its cost-per-usable-kWh over the life of the build is usually higher despite the lower sticker price.
Which should you choose?
- Choose LiFePO4 for full-time or heavy use, weight-sensitive builds, and anyone who wants to actually use most of the battery. It is the default for a reason.
- Choose AGM only for tight budgets, light or occasional use, or when sub-freezing charging without a heater is unavoidable.
Read the full LiFePO4 vs AGM guide for lifespan and safety detail, or size your own bank below.
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