How to predict a battery's lifespan?

Dear Car Talk

Dear Car Talk | Dec 01, 1989

Dear Tom and Ray:

Is there any method to determine when an automobile battery is getting toward the end of its life expectancy? Our last battery was working perfectly until it went dead completely without warning. Fortunately, it happened in our garage, but if it had occured at a distant location, I could have been in real trouble.

TOM: My Grandfather went like that. He was doing fine. Then he came home from the mud wrestling matches one day, plopped down in his favorite rocking chair, took a sip of warm schnapps, and that was it. We didn't even have the option of jump starting him!

RAY: It's impossible to predict the exact moment of expiration, Kathleen. Sometimes you'll get a hint like slower cranking, but you have to be pretty sensitive to notice it. If it absolutely terrifies you to have a dead battery, you could replace your 50 month battery after 40 months. But that's no guarantee that it won't die (if you have a short circuit or leave your glove box light on) and it's no guarantee that something else in the car won't fail suddenly and unexpectedly some day.

TOM: So we have two recommendations for you. First, keep a copy of War and Peace in the car. It won't teach you diddly about car repair, but it'll help pass the time while you're waiting for the tow truck. Second, try to nurture a more casual attitude toward these inevitable inconveniences. Keep them in perspective. Remember, you can always get a new battery for your car. Even Grandma's begun to interview for a new fourth for bridge!

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