A lithium (LiFePO4) battery should be charged with a charger that has a lithium or LiFePO4 profile, set to the voltages the battery maker publishes. These are typically around 14.2 to 14.6 volts absorption for a 12V battery, with a low float or no float. Avoid equalize and desulfation modes, which push voltage high enough to trip the battery’s protection, and do not charge below freezing unless the battery has a built-in heater.
Why lithium needs a different charger
Lead-acid chargers are built around multi-stage charging with a long float and occasional high-voltage equalizing. A LiFePO4 battery accepts current efficiently right up to full, does not need a float to stay healthy, and has a battery management system (BMS) that disconnects it if voltage or temperature goes outside its limits. A charger made for lead-acid may stop short of full charge, float too high, or trigger the BMS.
Can you use a lead-acid charger?
Sometimes, but check the battery maker’s guidance. An AGM profile can come close on some chargers, but it may not fully charge the battery or may hold it at a higher float than the maker recommends. Never use a flooded-battery profile with equalization or a desulfation mode on a lithium battery.
Charging in the cold
Most LiFePO4 batteries must not be charged below about 32°F (0°C), because charging a cold cell can damage it. Many have a BMS that blocks cold charging. Batteries with an internal heater warm themselves before accepting charge, which suits early-season and late-season anglers. The Lithium 12V 300Ah LiFePO4 battery with Bluetooth and heater ($1,599.00) is built this way.
What is a wake-up feature?
If a lithium battery is run down far enough, its BMS shuts the output off to protect the cells, and the terminals can read near zero volts. Many chargers then refuse to start because they cannot detect a battery. A charger with a lithium wake-up or reactivation mode applies a small current to bring the BMS back online. Follow the battery maker’s recovery procedure if yours does not have one.
Sizing the charger
- Check the battery maker’s maximum charge current, and pick a charger at or below it.
- For 24V and 36V trolling setups, an onboard multi-bank charger charges each 12V battery separately, which keeps them balanced.
- If you charge from the engine’s alternator, a DC-DC charger with a lithium profile protects both the alternator and the battery.
Bundles and batteries we list
See the LBP Lithium Battery Bundles ($970.00); check the listing for what each bundle includes. For the bigger picture, read lithium vs lead-acid trolling batteries, how long do lithium batteries last?, how to charge a trolling motor battery and trolling motor wiring.
More guides: how many amp hours you need for a trolling motor · lithium batteries in cold weather · LiFePO4 vs lithium-ion.
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