Posted by Peter Kennedy on 11/11/2022 to Batteries (Lithium Ion)
Everyone knows that lithium batteries cannot be charged if they are below freezing. With our Victron Smart Lithium Batteries charging is automatically disabled by the BMS when the temperature gets below 5 Deg C. They wanted a bit of extra margin just to be on the safe side. Other battery manufacturers put similar limits on their batteries.
There is not a similar temperature limit for discharging. Most batteries can continue to provide power below freezing. This means that in an extended cold spell a battery could become depleted by a continuous load but not be able to be recharged because of the temperature restriction. An example of this might be a boat, where a bilge pump is left on but where the battery cannot be recharged in cold weather. An example in an RV or van might be something like a phone charger that is left on all the time. If the vehicle is not in use and the battery is cold enough the battery will eventually get depleted.
Lithium battery systems all get some kind of Battery Management System to disable loads when the battery gets empty If you leave things turned on in your boat or RV during a cold spell in the winter you will find out if your protection system worked. If it did all you will have to deal with is a flat battery that can be recharged once it warms up. If your protection system was miswired your battery may become discharged beyond repair.
There are a couple of ways to deal with this problem and the simplest and most obvious one is to disconnect the lithium battery system when it is not in use. No harm will come to the battery if it is sitting in cold weather as long as it is not being used. There is no liquid in the battery to freeze. Leave everything disconnected and you wont have any worries. If you have a boat in the water and want to leave the bilge pumps on then temporarily connect them to the conventional starting battery. You will still have to keep it charged up of course but conventional batteries are not subject to the same restrictions on temperature when charging.
As an alternative you can arrange to keep your lithium battery warm enough to operate in cold weather, either by heating your boat or RV or by wrapping the battery in an electric warming blanket. One manufacturer that specializes in warming blankets is Annod Industries Inc. This works fine but of course you will need to monitor it to make sure the heater is working. If you choose this method then remote access from the Victron VRM will be a very useful as a way of keeping a check on your system. This will allow you to monitor your boat without walking down an icy dock.
So to summarize: Yes by all means winterize your Lithium Battery. If it is not being used all you have to do is disconnect it. You will have peace of mind and can come back and start your system up again when the weather warms up