Piston Slap: Change Batteries Like Oil. Or Not.

Sajeev Mehta
by Sajeev Mehta

Jonathon writes:

Sajeev, I grew up and still live in Chicago. Following the habits of my parents, I always replace a battery after four Chicago winters. Can modern batteries withstand the cold climates better than their predecessors, or should I replace that 4 year old battery this fall?

Sajeev answers:

I do not know if car batteries evolved like their internal combustion

brethren, but modern automobile electronics demand more robust

juiceboxes. Thirty years ago, you’d be hard pressed to find an

alternator with more than 80 amps in a mainstream American passenger

car. But today? Good luck finding a car with less than 120 amps in

an alternator that doesn’t look like the center section of a TIE


But more importantly, none of this matters: only replace a battery

when it fails a diagnostic test. A parts store can test it (in the

car) for free, usually in less than 10 minutes. Or, for the charging

system OCDs of the world, spend a few bucks for some kind of cigarette

lighter mounted tester for accurate results in seconds. The testers

are idiot proof and might keep you from blowing $100 (or so) for a new

battery when you could put off that expense months later. You know,

maybe after you pay off your credit card during your Christmas

shopping binge.

[Send your queries to mehta@ttac.com]

Sajeev Mehta
Sajeev Mehta

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4 of 42 comments
  • Bschiek Bschiek on Oct 29, 2009

    An additional point of interest: I read somewhere (CR?) that the difference between the battery with a 2 year free replacement and 3 year free replacement warranty is simply an insurance policy. There is no material difference in the batteries, the extra cost is simply the insurance premium for the additional warranty time. Can the Best and Brightest confirm as fact?

  • Aoliveiro Aoliveiro on Oct 29, 2009

    Sajeev, My dad has run an auto electric shop for 30 years. He says to replace every 4 years. An old battery may start the car, but will put undo stain on the alternator. A weak battery is the number one cause for alternator failure.

  • Jacob Jacob on Oct 29, 2009

    Once I bought one of those "premium" Autozone batteries with a three year full replacement warranty when I was living in California. Then I moved to Indiana. Exactly three years after buying it, the battery died.. 2 days after the full replacement warranty expires. Fortunately, Autozone was nice enough to replace it for free.

  • Jacob Jacob on Oct 29, 2009

    I still live in Indiana. A few years later I will come back to report how long the second Duralast battery lasted.