LiFePO4 vs AGM Batteries for Campervans: The Real Comparison

Choosing between LiFePO4 (lithium iron phosphate) and AGM (absorbed glass mat) batteries is one of the biggest decisions in your campervan battery setup. The right choice depends on your budget, usage pattern, and how long you plan to keep the van.

This guide gives you the honest comparison — no manufacturer spin, just real-world data from UK van conversions. For the complete battery overview, see our campervan battery guide.

The Key Differences

Usable Capacity

This is the single biggest difference and the one most people underestimate:

• AGM: You can safely use 50% of the rated capacity. A 100Ah AGM gives you 50Ah usable.
• LiFePO4: You can safely use 80% of rated capacity. A 100Ah LiFePO4 gives you 80Ah usable.

This means a 200Ah LiFePO4 battery gives you more usable energy than two 200Ah AGM batteries.

Weight

LiFePO4 batteries weigh roughly half as much as equivalent AGM batteries:

For a van conversion where payload matters, this weight saving is significant.

Lifespan (Cycle Life)

• AGM: 300-500 cycles at 50% depth of discharge
• LiFePO4: 3,000-5,000 cycles at 80% depth of discharge

In practical terms, an AGM battery might last 2-3 years of regular use. A LiFePO4 battery will last 8-10+ years.

Cost

AGM wins on upfront cost:

• 100Ah AGM: ~£150-£200
• 100Ah LiFePO4: ~£250-£350
• 200Ah LiFePO4: ~£450-£600

But on a cost-per-usable-Wh-per-cycle basis, LiFePO4 is dramatically cheaper over its lifetime.

Charging

Both can be charged from solar, DC-DC chargers, and shore power. However:

• LiFePO4 accepts charge much faster (can handle higher charge currents)
• LiFePO4 needs a charger with a LiFePO4 profile (most modern chargers have this)
• LiFePO4 has issues charging below 0°C — see cold weather charging

When AGM Makes Sense

AGM is the right choice if:

• You're on a very tight budget
• You only use the van occasionally (a few weekends per year)
• You're building a temporary/trial setup before committing to lithium
• You need a drop-in replacement for an existing lead-acid setup

When LiFePO4 Makes Sense

LiFePO4 is the right choice if:

• You use the van regularly (monthly or more)
• You're full-time or doing extended trips
• Weight matters (smaller vans, payload-sensitive)
• You want a "fit and forget" solution that lasts years

For most builds we see in 2025, LiFePO4 is the better choice. The price gap has narrowed significantly, and the Fogstar Drift range offers excellent value.

See our best lithium batteries for campervans for specific product recommendations, and use our calculator to size your battery bank.

FAQ

Is LiFePO4 worth the extra cost for a campervan?

For most van conversions, yes. The longer lifespan, lighter weight, and higher usable capacity mean LiFePO4 is cheaper per usable Wh over its lifetime. The main exception is very occasional use (a few times per year).

Can I replace my AGM with LiFePO4?

Yes, but you'll need to ensure your chargers (DC-DC, MPPT, shore) support LiFePO4 charging profiles. Most modern chargers do. You may also need to adjust charge voltages.

Do LiFePO4 batteries need a BMS?

Yes, and all quality LiFePO4 batteries come with a built-in BMS (Battery Management System). The BMS protects against overcharge, over-discharge, short circuits, and temperature extremes. Never buy a LiFePO4 cell without a BMS.

Can I mix AGM and LiFePO4 batteries?

No. Never mix battery chemistries in the same bank. They have different voltage profiles and charge characteristics, which will cause problems.