I live in a place where it gets cold, -40 and colder kind of cold. We have plugs on our cars for block heaters. Basically, if you don't plug in your car in very cold weather, and the battery gets too cold, you aren't going to get a spark to start your engine, you will need a boost and probably have to hook up a battery charger along with the block heater to get a full charge back in your battery.