Most manufacturers state that you should not charge below 0C, but most will assume that most consumers cannot handle the charging rate. RELION who is an important player in the low-temperature battery market, particularly in Canada, says about generic batteries: "Important tips to keep in mind: When charging lithium iron phosphate batteries below 0°C (32°F), the charge current must be reduced to 0.1C and below -10°C (14°F) it must be reduced to 0.05C. Failure to reduce the current below freezing temperatures can cause irreversible damage to your battery." There exist chargers in the market for charging lithium batteries at low temperatures, and I expect that they adapt the charging rate to the temperature. I put my LifePO4 batteries on my main bike in 2017 and have commuted mostly on that bike every workday, every winter. I usually return when it is dark and can tell that the battery capacity has not markedly dropped from operating a horn parallel to my lights: The horn takes up to 2A, and the lights do not dim. The conditions under which I activate the horn are usually when I am slow or stopped. My batteries are exclusively charged from the dynohub. The bike is parked outside when I am at work and it freezes in the garage at home, too.