Swapping a tired AGM for a LiFePO4 cell is the single highest-impact upgrade most RVers make — more usable capacity, less weight, longer life. The swap itself is simple, but a few steps separate a clean install from a costly mistake. Here's the safe way.
The quick answer
Disconnect negative first, remove the old battery, mount the new LiFePO4 securely, reconnect with proper fusing, and — critically — set your converter/charger to a lithium profile. The physical swap is an afternoon; the charger setting is what keeps the new cell healthy. Our charging guide covers the profiles in detail.
HumsiENK 100Ah LiFePO4 (Bluetooth)
Safety first
- Kill the shore power and inverter before touching anything.
- Remove the negative terminal first, replace it last — prevents a wrench-to-chassis short.
- Wear eye protection; keep metal tools from bridging terminals.
- Work in a ventilated area (matters more for lead-acid, but good habit).
Step-by-step
- Document the wiring with a photo so you reconnect identically.
- Disconnect negative, then positive; lift out the old battery.
- Prep the tray. LiFePO4 is lighter but must still be held down against road vibration — use the existing hold-down or a battery box.
- Add a fuse/breaker on the positive near the battery (proper fusing is non-negotiable on a high-current lithium bank).
- Connect positive first, then negative, with clean torque on the terminals.
- Set the converter to lithium (see below), then do a full charge so the BMS can balance.
The converter/charger profile
| Your converter | Action |
|---|---|
| Has a LiFePO4 / lithium setting | Select it. Done. |
| Lead-acid only (no lithium) | Swap in a converter with a lithium profile (~$30–$90) |
| Multi-stage smart charger | Confirm absorption ~14.2–14.6V; adjust if needed |
Without the right profile the BMS clamps the charge and the bank never fills — a top complaint in first-time upgrades. The voltage chart helps you confirm a full resting charge afterward.
Gotchas that trip up first-timers
- Forgetting the charger setting — the #1 issue.
- No fuse on the positive — a short on a 100Ah+ bank is violent. Fuse it.
- Loose mounting — vibration cracks terminals and cases.
- Mismatched banks — don't mix old AGM with new lithium in parallel; let the new bank stand alone.
- Storage habits — lithium wants ~50% SoC in storage, not full like AGM. See winter storage.
Shop the batteries
314Ah LiFePO4 — best for full-timing
Mounts, fuses, and monitors:
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Frequently asked questions
Can I just swap AGM for lithium in my RV?
Electrically, yes — the terminals and voltage match. But you must set your converter/charger to a lithium (LiFePO4) profile, secure the lighter battery properly, and check venting and fusing for the new bank.
Do I need to change my RV converter for lithium?
Only if it lacks a lithium charging profile. Many stock converters are lead-acid only; a $30–$90 converter with a lithium setting fixes it. Without it, the BMS will clamp the charge and you'll under-charge.
Do I need a battery box or venting for lithium?
LiFePO4 is sealed and doesn't off-gas like lead-acid, so active venting isn't required. You still need solid mechanical mounting to survive road vibration — a box or hold-down is the right call.
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