The single biggest battery decision for any RVer is lithium (LiFePO4) versus AGM (a sealed lead-acid). The marketing makes lithium look obviously better — and for most people it is — but AGM still has a place. Here's the real comparison without the hype.
Upfront cost
A 100Ah AGM runs $139–$199. A comparable 100Ah LiFePO4 starts around $249 and climbs past $399 for premium heated cells. On day one, AGM is roughly 40% cheaper.
Cycle life — where lithium wins big
This is the number that matters most. AGM delivers 300–600 full cycles before dropping to 80% capacity. LiFePO4 delivers 3,000–5,000. Do the math on cost-per-cycle and lithium is often 5× cheaper over its life.
| LiFePO4 | AGM | |
|---|---|---|
| Cycles to 80% | 3,000–5,000 | 300–600 |
| Cost per cycle (100Ah) | ~$0.07 | ~$0.40 |
Weight and space
A 100Ah LiFePO4 weighs about 26 lbs; an AGM about 63 lbs. If you need 200Ah of usable capacity, that's two lithium at ~52 lbs versus four AGM at ~250 lbs. For smaller rigs and vans, weight alone decides it.
Cold weather
Standard lithium refuses to charge below freezing and can be damaged if forced. AGM handles cold better but loses capacity. If you camp in winter, buy a heated LiFePO4 or stick with AGM for the shoulder seasons.
Who should buy which?
- Buy lithium if you camp regularly, value weight, want multi-day off-grid runtime, and plan to keep the rig for years.
- Buy AGM if you're a weekend warrior on a tight budget, or you only need short bursts of power and don't mind the weight.
Our favorite lithium — HumsiENK 100Ah LiFePO4 (Bluetooth)
Best for certified installs — HumsiENK LiFePO4 (UL9540A)
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