The gain in usable energy
Lead-acid batteries are usually planned at about half their rating because deeper cycling shortens their life. LiFePO4 batteries tolerate deeper cycling: Victron, for example, rates its LFP Smart range at about 2,500 cycles to 80% depth of discharge. So the same Ah rating delivers more usable energy.
| Battery | Usable energy | Autonomy |
|---|---|---|
| 100 Ah AGM at 50% | 600 Wh | 0.9 to 1.1 days |
| 100 Ah LiFePO4 at 80% | 960 Wh | 1.5 to 1.8 days |
- Usable energy
- 960 Wh
- Daily use
- 530 Wh
- Daily charging
- 0 Wh
- Autonomy
- 1.5 to 1.8 days
Switch chemistry in the calculator to see the AGM figure for the same loads.
Open in the calculatorEvery charging source has to agree
A lithium battery charges best with the charging voltage and profile its maker specifies. Many campers have three or four chargers: a mains charger, a solar controller, a charge path from the alternator and sometimes a generator. Each needs a lithium setting that matches the battery datasheet, or it has to be replaced.
| Component | Question |
|---|---|
| Mains charger | Does it have a lithium profile, and can its voltages match the battery datasheet? |
| Solar controller | Can it be set to LiFePO4 values, or only to lead-acid presets? |
| Alternator path | Is there a DC-DC charger, or does the starter battery charge the leisure battery directly? |
| Battery monitor | Can it be reset for the new capacity and chemistry? |
| Fuse and isolator near the battery | Are they rated for the new battery? Ask an installer to confirm. |
| Control panel or habitation unit | Does the manufacturer support lithium on this unit? |
The alternator is the usual surprise
Many newer vehicles with Euro 5 and 6 engines have smart alternators that vary their output voltage. Victron notes that these often give too low a charging voltage for a second battery, and long cable runs lose more along the way. A DC-DC charger regulates the charge to the leisure battery and is a common answer, but whether you need one depends on the vehicle and the wiring.
Cold limits charging, not just range
LiFePO4 batteries can usually discharge in the cold but must not be charged below a minimum temperature. That minimum differs by model. Victron lists 5 °C for some Smart batteries and 0 °C for others. If you travel in winter, check whether your battery has internal heating or low-temperature charge protection in its BMS.