The Real Question
The question isn't which battery is "better" — it's which battery is better for your use case and timeline. A weekend warrior who builds once and sells their van in 2 years has a very different calculation than a full-timer who will spend 5 years in their rig.
Side-by-Side Comparison
| Feature | LiFePO4 Lithium | AGM Deep Cycle |
|---|---|---|
| Usable Capacity | 95% (190Ah of 200Ah) | 50% (100Ah of 200Ah) |
| Cycle Life | 3,000–5,000 cycles | 300–500 cycles |
| Weight (200Ah) | ~26 lbs | ~130 lbs |
| Upfront Cost (200Ah) | $500–$800 | $150–$250 |
| 5-Year Total Cost | $600–$900 | $700–$1,500 (replacements) |
| Charge Speed | Very fast (accepts full charge rate) | Slow (tapers significantly) |
| Temperature | Cannot charge below 32°F | Works in cold (charging) |
| Maintenance | Zero | Check water (wet) / minimal (AGM) |
| BMS Included | Yes (quality brands) | No |
The 5-Year Math
Assume you're running 200Ah of storage, full-time, cycling daily:
| Year | Lithium Cost | AGM Cost |
|---|---|---|
| Year 1 | $650 (purchase) | $200 (purchase) |
| Year 2 | $0 | $0 |
| Year 3 | $0 | $200 (replace — AGM dead by now) |
| Year 4 | $0 | $0 |
| Year 5 | $0 | $200 (replace again) |
| 5-Year Total | $650 | $600 |
💡 The Verdict Over 5 years, costs are nearly identical — but lithium gives you TWICE the usable capacity and weighs 80% less. For full-timers, lithium wins clearly. For weekend warriors who'll resell quickly,
AGM is totally fine.
Lithium Cold Weather Warning
LiFePO4 batteries cannot be charged below 32°F (0°C) without damaging the cells. This is a hard limit. Solutions: buy a battery with an internal heater (Battle Born and Renogy offer this), insulate the battery compartment, or use a battery with a built-in low-temperature cutoff BMS. In the desert Southwest? Never an issue. Alaska in January? Plan accordingly.
Recommended Brands
Lithium (LiFePO4)
- Battle Born — the most popular, rock solid BMS, made in the USA, 10-year warranty
- Ampere Time — excellent value, solid cells, lower price point
- Renogy — good mid-range option, wide availability
- Epoch Batteries — newer but impressive quality and value
AGM (if that's your choice)
- Battle Born AGM — premium quality
- VMAX Tanks — popular, good cycle life for AGM
- Renogy Deep Cycle AGM — widely available and reliable