Lithium batteries, including the LiFePO4 batteries used in boats, can be used in cold weather but must not be charged below freezing (32°F / 0°C) unless they are heated or the maker specifically allows it. Charging a cold lithium cell can plate lithium metal inside it, permanently reducing capacity and creating a safety risk. Discharging in the cold is generally allowed down to a lower limit set by the maker, though available capacity drops as the battery gets colder.
What cold does to a lithium battery
- Charging: not below freezing without a heater or the maker’s approval.
- Discharging: allowed to a lower temperature, but with reduced capacity and voltage.
- Storage: lithium batteries tolerate cold storage well, usually better than lead-acid, as long as they are stored at a sensible charge level.
How batteries protect themselves
Most quality LiFePO4 batteries have a battery management system (BMS) that blocks charging when the cells are too cold. Some also have built-in heaters that warm the cells before allowing a charge, which is useful for ice fishing, early-season fishing and boats stored in unheated spaces. Our listed Ionic 12V 300Ah includes a built-in heater and Bluetooth monitoring.
Charging lithium below freezing
- Use a battery with a heater, or bring the battery into a warm space before charging.
- Check the battery’s temperature on its app or monitor if it has one.
- Do not bypass or override the BMS low-temperature cutoff.
- Use a charger with the correct lithium profile; see lithium battery chargers.
Using lithium in cold-weather fishing
Expect less run time on very cold days, because the cells deliver less of their capacity when cold. Insulating the battery compartment helps, and a battery that warms itself as it works will recover some capacity. Plan for the lower run time when sizing the bank; see how many amp hours you need.
Winter storage
Store lithium batteries at a partial charge as the maker recommends, disconnect them from loads to prevent slow drains, and check the charge level occasionally. Unlike lead-acid, they do not need to be kept on a float charger all winter. See how to winterize an outboard for the rest of the boat.
Lithium vs lead-acid in the cold
Lead-acid batteries can be charged in the cold but lose capacity and can freeze if left discharged. Lithium avoids the freezing risk in storage but needs care with charging. See lithium vs lead-acid and LiFePO4 vs lithium-ion.
LiFePO4 batteries we list
- LBP Lithium Battery Bundles (12V 100Ah or 36V 60Ah, with onboard charger and tray): $970.00
- Ionic Lithium 12V 300Ah LiFePO4 with Bluetooth and heater: $1,599.00
Shipping is a flat $80.00 per order to US addresses, with 15-day free returns. Questions? Ask a parts specialist.