How to Winterize a car battery
Have your battery tested. If your battery is at least 3 years old, take it to a certified automotive repair facility. You do not want your battery, whose power is reduced by 50 percent during the cold weather, to go dead while you're in the middle of a snowstorm. If they are younger than that, make sure that the battery's posts and connections are free of corrosion. Also, make sure that your battery has all the water it needs.