How Often Should You Start Your Car in 0 Degree Weather?

by Rob Wagner
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The car battery is perhaps the most neglected automotive part. This spells doom for motorists stranded on the roadside or forced to purchase a $100 battery at an inconvenient time during the winter. But simple precautions can ensure battery survival through subfreezing temperatures during the winter. Cars that would otherwise be idle for long periods may require daily starting.

General Rule

Owners should start their car daily in zero-degree temperatures. Auto mechanics may advise starting a vehicle once a week to ensure continued battery life, but this is under the best circumstances. If a car is kept in a garage each night, or better yet a heated garage, then starting a car with a healthy battery is not a problem. But weekly starting does not take into account cars equipped with older or weak batteries or with numerous options that consume power, and cars parked outside overnight in subfreezing temperatures. Only daily starting or disconnecting the battery will guarantee a working battery in the morning.

The Hungry Battery

A car battery is a hungry beast. An idle, parked car with the engine off still consumes power. The anti-theft device, clock and other power accessories use battery power while you sleep. Automobiles with performance engines use even more power. Performance engines use bigger and more spark to start and can drain the battery with an electric power steering component and electric water pump. Under the best conditions, a battery in good condition can recharge itself once the engine is running. But the battery’s chemical reaction to charging slows down and reduces power output in cold temperatures. Simply put, cold weather puts tremendous strain on even the most powerful batteries. A vehicle's battery strength drops about 60 percent at zero degrees F and 35 percent at 32.

Daily Starting

Starting the car daily even if you're not driving it each day ensures the battery receives a fresh charge. Run the engine for a few minutes. But keep in mind that a weak battery may not keep a full charge and daily starting won’t help it. A weak battery may function perfectly in mild weather conditions, and the average motorist is probably unaware the battery is weak. Cold weather will quickly sap the life from it.

Unhook the Battery

The best weapon to prevent a dead battery on a cold winter morning is to unhook it. With a single crescent wrench, a car owner can disconnect the ground battery cable from the post so no electrical component will consume the battery’s power. But the anti-theft device, clock and other powered accessories will not function. Naturally, unhooking the battery requires the motorist to re-attach the cable each time to start the car. The tradeoff to not having an anti-theft device operative overnight is saving the battery.

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