Lithium Batteries Off-Road

Lithium batteries (LiFePO4) for off-road and expedition vehicles

Lithium iron phosphate batteries (LiFePO4) are today the most capable basis for self-sufficient power in a vehicle. They deliver high charge and discharge currents with very stable voltage, weigh far less than lead batteries and last several thousand charge cycles. In this category you will find lithium batteries for 12 V, 24 V and 48 V systems from BullTron, SuperB, Mastervolt and EP-Technologies, each with an integrated battery management system.

The advantages at a glance

• Short charging times: charge currents up to 1 C – a 100 Ah battery is full in about one hour at 100 A.
• Full power to the end: 1 C to 3 C continuous and up to 10 C for short periods, without the voltage drop of lead. Ideal for combi inverters, a coffee machine or an induction hob in the habitation unit.
• Low self-discharge: less than 3 % per month; the battery can also stand partially charged during longer periods of non-use.
• Up to 70 % lighter: decisive with limited payload. A 210 Ah LiFePO4 battery weighs around 23 kg, a lead battery of the same nominal capacity around 70 kg.
• Almost the full capacity is usable: with lead, only about 50 % of the nominal capacity is really usable.

Control and monitoring

The integrated battery management system (BMS), together with an internal or external relay, protects the cells against overcharging and deep discharge, monitors cell temperature and balances the individual cells. The P-BUS-capable BullTron models (suffix “-P”) report state of charge and temperature directly to the philippi system monitors.

Frequently asked questions about lithium batteries in vehicles

Which charger do I need for a LiFePO4 battery?

A charger with a LiFePO4 profile or a freely adjustable charge voltage set to the battery manufacturer's specification. The philippi ACE chargers have suitable lithium programs. A pure lead charger with float and equalisation charging is unsuitable because it can put the cells under too much stress over time. At the alternator a charge booster is also needed, especially in modern vehicles with a regulated alternator.

May I charge a lithium battery below 0 °C?

As a rule not, or only with a greatly reduced charge current. Below 0 °C, metallic lithium is deposited during charging, which damages the cell. Many manufacturers allow at most 0.1 C below 0 °C, others block charging completely via the BMS. The data sheet of the specific battery is what counts; in winter the battery therefore belongs in the heated interior.

Can I simply replace my leisure battery with lithium?

Usually yes, but not without adjustments. Charger, solar regulator and alternator regulation must be set to the lithium profile, the battery monitor needs new parameters, and a charge booster at the alternator makes sense. The Academy article Converting from AGM to lithium shows exactly what to do.