Have you ever gone out to start your car in the winter only to find that the battery does not have enough power to crank over the engine. Or worse yet, that your battery is dead from the cold weather. This used to happen to me, too, but no more since I made the switch to an EV.
Electric vehicles are designed to charge both the high-voltage and the 12 volt battery in the vehicle when connected to a charger. When plugged in they will first charge the high-voltage battery and then switch to charging the 12 volt battery as needed.
But do take care if you have left your EV unplugged for a few days. It would then be best to allow it to stay plugged in for at least 24 hours. That is because there are certain criteria under which the charging system does not immediately switch to charging the 12 volt battery even if the high-voltage battery is fully charged.
And just like a petrol powered vehicle, an EV won’t start without its 12 volt battery. So if you plan to not use your EV for a few days, especially in cold weather, it is best to leave it plugged in to a charger so both the high-voltage and 12 volt battery stay charged and ready to go.