I have recently bought a 2012 I-Miev. The car is badly rusted. I have decided not to use it in the winter. I am in Ontario, and it can get cold in the winter. I have noticed, that the main battery doesn't have any noticeable discharge with the car parked. The 12V battery when disconnected, also discharges only minimally.
A top up once a month would do.
But when the 12V battery is connected, it discharges faster, and I would have to charge the 12V battery once a week. It likely keeps the computer memory. I don't care about that.
My first plan was to discharge the main battery to 40%, and disconnect and charge the 12V battery.
And check the status of the main battery once a month, and top it up to 40% if needed.
Then I have found about the main battery using a heater to heat itself when it is colder than -25C. Does it do it when the car is off?
Would it do it when 12V battery is disconnected? How bad would it be not having this feature? It can get to -25 degrees C at night, but maybe only 10 times in the winter. Most of the time it is -5 to -20 degrees C.
Thank you for your reply.