I’m considering buying an EV to replace my aging diesel. I live in a very cold country where temperatures regularly dip below -30C in the winter.
I understand that EVs lose range in cold temperatures and that they need heating to use and charge without damage.
My question is this: if I plan on not using my car for several weeks, can I leave it unplugged and/or tell it to stop managing the batteries’ temperature to save energy and not damage the batteries?
I’m okay with spending half a day preheating it when I plan on using it again regularly, but I don’t want it to draw current all the time for nothing when I’m away on long missions.
For some reason, I can’t seem to find out if it’s safe to keep a fully unpowered EV in the cold for a long time…
It depends on a lot of factors including the battery chemistry.
NMC (Lithium ion) batteries are common in high performance cars and older EVs. They should be kept between 20% and 80% charge for normal use. 60% is ideal for storage, but anywhere in that range will do.
LFP (Lithium ion) batteries are common in cheaper and newer EVs. They don’t have a problem with being stored at 100%, and do have issues with not being regularly charged to 100% (monitoring gets less accurate over time until fully charged again), so leaving it at 100% is fine.
Lead acid (particularly calcium) batteries get damaged when discharged too much, so it’s fairly important to keep them topped up. If you are leaving the car for a long time, it could be worthwhile to connect a trickle charger to the 12V battery to prevent the car’s computer from gradually draining the battery. Some cars will top up the 12V battery from the high voltage battery if left for a while, so this may not be needed.
While I have little experience with low temperatures, I suspect that the car will be fine if left as stated above. The battery shouldn’t get damaged by low temperature storage, and shouldn’t lose much charge over time. Just don’t expect full performance immediately after returning to it.