How to Charge a LiFePO4 Battery in a Campervan
LiFePO4 batteries charge differently from AGM and gel lead-acid batteries — and using the wrong charger profile can either damage the battery or leave you chronically undercharged. Here is how to do it correctly.
LiFePO4 charging voltage profile
A LiFePO4 cell charges to a maximum of 3.65V per cell. In a 12V battery (four cells in series), the pack maximum is 14.6V. Most battery manufacturers recommend a slightly conservative 14.4V absorption voltage to extend cycle life.
| Stage | Voltage | Notes |
|---|---|---|
| Bulk | Up to 14.4V | Charger pushes maximum current |
| Absorption | 14.4V | Hold until current drops to ~5% of C rating |
| Float | 13.5–13.8V (or off) | LiFePO4 does not need float charging |
Key difference from lead-acid: LiFePO4 does not benefit from float charging. Many battery manufacturers recommend disabling float entirely, or setting it to 13.5V so the charger does not constantly cycle. A good battery will hold its state of charge for weeks without a trickle charge.
What chargers work for LiFePO4
You need a charger with a dedicated LiFePO4 profile. Standard lead-acid settings undercharge LiFePO4 (often stopping at 14.2V with extended absorption, missing the top 10% of capacity).
Mains battery chargers:
- Victron Blue Smart IP67 (Bluetooth, adjustable profile) — excellent choice, set to Li profile
- CTEK MXS 25 (has LiFePO4 mode)
- Renogy 40A DC Home Battery Charger
DC-DC chargers (alternator charging):
- Victron Orion-Tr Smart — set LiFePO4 output voltage to 14.4V
- Sterling Power B2B — configurable output profile
- Renogy DC-DC 40A — LiFePO4 compatible
Solar charge controllers:
- Victron SmartSolar MPPT — built-in LiFePO4 preset (14.4V absorption, 13.5V float)
- Renogy Rover MPPT — has LiFePO4 mode
Setting up your charger for LiFePO4
For any configurable charger, set:
- Absorption voltage: 14.4V (or up to 14.6V if manufacturer specifies)
- Float voltage: 13.5V or disabled
- Maximum charge current: Up to 1C (e.g., 100A for a 100Ah battery) — LiFePO4 accepts fast charging
- Tail current (end of absorption): 5% of capacity (e.g., 5A for 100Ah battery)
Do not use equalisation — LiFePO4 batteries do not require or tolerate equalisation cycles.
Charge current: how fast can you charge LiFePO4?
LiFePO4 accepts charge at up to 1C (100Ah battery = 100A charge current). In practice, your charger and cable sizing will be the limiting factor. Most van builders charge at 20–50A, which is sufficient.
Example charge times (100Ah LiFePO4, starting at 20%):
- 20A charger: ~4 hours to full
- 40A charger: ~2 hours to full
- 100A charger: ~1 hour to full
Temperature limits for charging
LiFePO4 cells must not be charged below 0°C. Most quality batteries include a built-in BMS that disconnects charging when the cell temperature is below freezing. If you are camping in winter and the battery is cold, the BMS may prevent charging until the cells warm up.
Some batteries (e.g., Victron Smart LiFePO4, Battle Born) include self-heating circuitry that warms the cells before charging begins.
FAQ
Can I charge a LiFePO4 battery with my existing AGM charger?
Only if it has a specific LiFePO4 mode. AGM chargers without a LiFePO4 setting use incorrect voltage profiles and extended absorption phases. Check your charger's manual — if it has no LiFePO4 preset, replace it.
Does LiFePO4 need a different solar charge controller?
Yes — configure your MPPT controller with the correct LiFePO4 absorption voltage (14.4V) and a low or disabled float. Most modern MPPTs have a built-in LiFePO4 preset.
What happens if I overcharge a LiFePO4 battery?
The BMS (battery management system) in the battery will disconnect charging when the cell voltage exceeds the safe limit. Chronically overcharging (pushing to 14.6–15V regularly) can degrade cell capacity over time, but the BMS prevents acute damage.