Charging lithium iron phosphate below zero Celsius plates metallic lithium onto the anode. The damage is permanent and it does not announce itself, so every BMS refuses charge below a cutoff temperature, usually right around freezing.
Discharge is fine well below that. The pack will run your house at minus ten and refuse every amp the solar array offers, which is the failure people meet in January: full sun, working panels, and a bank that sits at 40 percent all day.
What actually happens at the cutoff
Behaviour varies and the variation matters. Some packs open the charge path and report a fault. Some accept a reduced current. Some report nothing at all and simply stop counting, which leaves an inverter with no comms link showing a charge stage that is not charging.
The published cutoff is also measured somewhere specific, usually at a cell or on the BMS board, and a pack in an unheated shed reaches that temperature well before the air in the room does.
Three answers, and one that is not
Self heating packs draw a small current to warm the cells before accepting charge. That is the least intervention and it costs energy from the same bank.
Conditioned space is the cheapest answer when it is available. A pack in a utility room rarely reaches its cutoff.
An insulated enclosure with a thermostatically controlled heater covers a garage or shed install, and it needs the heater powered from something that works when the battery will not charge.
Setting the cutoff lower in BMS software is not an answer. The limit is chemistry, not policy, and packs that let you move it are letting you damage them quietly.
Cold weather hardware
Heated packs and enclosure heating, for installs that will see a real winter.
Self heating 48V batteriesBattery enclosure heatersAffiliate links. As an Amazon Associate this site earns from qualifying purchases, at no extra cost to you. Prices and stock change often, and a listing appearing here is not a statement that the pairing above is approved.