Converting Your Campervan to Lithium: Step-by-Step Guide
Switching from AGM or lead-acid to LiFePO4 in a campervan is one of the most impactful upgrades you can make. You will get more usable capacity, faster charging, longer life, and less weight. But it is not a direct swap — several parts of your system need to be reconfigured or replaced.
What you are gaining
| Metric | AGM 100Ah | LiFePO4 100Ah |
|---|---|---|
| Usable capacity | 50Ah (50% DoD) | 90–100Ah (90% DoD) |
| Cycle life | 400–600 cycles | 3,000–5,000 cycles |
| Weight | ~28kg | ~12–14kg |
| Charge acceptance | 25A max (0.25C) | 50–100A (0.5–1C) |
| Self-discharge | ~5%/month | ~2%/month |
| Charge voltage | 14.4–14.7V | 14.4V |
What you can keep
12V loads: All your 12V appliances (fridge, lights, fans, USB sockets) work identically on LiFePO4.
Solar panels: Panels themselves are unchanged — you're changing the charge controller settings, not the panels.
Wiring and fusing: Existing cable runs, fuses, and bus bars are compatible if correctly rated. Check that your main fuse is rated for the higher discharge current LiFePO4 allows.
What you must change or reconfigure
1. Charge sources — the most important step
Every charge source must be reconfigured for LiFePO4 voltage profiles.
Solar charge controller: Change to LiFePO4 profile. On Victron SmartSolar: absorption 14.4V, float 13.5V (or disabled). On Renogy Rover: select LiFePO4 preset. On a basic PWM controller without LiFePO4 mode: replace it — a PWM without correct voltage settings will undercharge.
DC-DC charger (B2B from alternator): Must be LiFePO4 compatible and configured correctly. A basic relay splitter is not suitable for LiFePO4 because LiFePO4's flat voltage curve means the relay cannot detect a "full" battery. Replace with a DC-DC charger (Victron Orion-Tr Smart, Sterling B2B).
Mains charger: Replace any old lead-acid-only charger with one that has a LiFePO4 mode. Victron Blue Smart, CTEK, or similar.
Alternator: Standard alternators work fine — the DC-DC charger handles the voltage conversion. You do not need to change your alternator.
2. Battery isolator / relay
Simple voltage-sensing relays (VSR) used to protect starter batteries do not work correctly with LiFePO4 because LiFePO4 holds a near-constant voltage during discharge — the relay cannot distinguish between full and empty. Replace with a DC-DC charger that actively charges from the alternator.
3. Low-voltage cutoff settings
If you use a battery protect or load disconnect device (Victron Battery Protect), recalibrate the low-voltage cutoff. For LiFePO4, set disconnect at 12.0V and reconnect at 12.6V (rather than the higher thresholds used for lead-acid). The BMS in the battery also handles this, but a Battery Protect provides a second layer.
4. Battery monitor / state of charge display
Lead-acid battery monitors often use voltage-to-SoC lookup tables calibrated for lead-acid voltage curves. LiFePO4 has a different (much flatter) voltage curve. Either use a monitor with a LiFePO4 setting (Victron BMV-712, Victron SmartShunt) or accept that a voltage-based SoC reading will be inaccurate on LiFePO4.
The conversion process
Step 1: Buy the LiFePO4 battery (or batteries). Common UK choices: Victron Smart LiFePO4, Fogstar Drift, REDARC, Battle Born, or a DIY build with CATL cells.
Step 2: Disconnect and remove old batteries. Note battery dimensions — some compartments are sized for AGM and may need modification.
Step 3: Install LiFePO4 battery. Connect cables to same terminals, same polarity.
Step 4: Reconfigure solar charge controller to LiFePO4 profile.
Step 5: Replace or reconfigure DC-DC charger with LiFePO4-compatible unit.
Step 6: Replace mains charger if not LiFePO4 compatible.
Step 7: Recalibrate battery monitor for LiFePO4. Many monitors require a full charge cycle before the SoC reading is accurate.
Step 8: Test each charge source: solar, alternator (via DC-DC), mains charger. Verify each tops the battery to ~14.4V then backs off.
FAQ
Do I need to change my fuse ratings when converting to LiFePO4?
Check your main fuse is rated for the higher discharge current LiFePO4 allows. If your battery has a 200A BMS, ensure your main fuse is 200A or lower. This is usually not a change from a well-installed AGM setup, but verify.
Can I mix AGM and LiFePO4 batteries?
No. Mixing battery chemistries in a parallel or series bank is not recommended — they have different voltage profiles, charge requirements, and discharge characteristics. Use a single chemistry throughout.
How do I dispose of old AGM batteries?
All lead-acid batteries must be recycled — they contain lead and sulphuric acid. Most car parts shops (Halfords, Euro Car Parts) and battery retailers accept lead-acid batteries for free recycling.