Ancient Greek Battery Mthology: Chapter II

Dear Car Talk

Dear Car Talk | Jun 01, 1991

Dear Tom and Ray:

I've heard that on a very cold morning, if you turn on the headlights for a few minutes before you start the car, the battery will be stronger when you try to start the engine. Is this true?

RAY: I think I read that in chapter two of Ancient Greek Battery Mythology, Leonard. When Agamemnon couldn't get the Trojan Horse started, he turned the headlights on for a few minutes, and the horse started right up.

TOM: Actually, Leonard, this myth is based on the theory that you are "warming up the battery" when you use it for a few minutes. But that sounds like a lot of hooey to me. While batteries do perform better when they're warm, turning on the headlights is not going to heat up the battery enough to make any difference. In fact, all you'll do is weaken the battery.

RAY: Think of the battery as a reservoir of energy. If you take some of that energy away--by using the lights, for example--there's less energy available to start the car.

TOM: So if you want to warm up your battery, Leonard, the best thing to do is leave the headlights off, and park the car in a heated garage.

Get the Car Talk Newsletter

Got a question about your car?

Ask Someone Who Owns One