Click & Clack: Battery corrosion is a sign of impending failure

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Dear Tom and Ray:

I have a 2007 Kia Spectra EX that does not start all the time, and it is getting corrosion on the battery terminals. My husband cleaned the terminals just a few weeks ago, and the corrosion is back. Can you please tell me what is going on and if a new battery will fix this issue?
— Jennifer

RAY: Probably. When you’re getting corrosion on the battery terminals, it’s often a sign that your battery is out-gassing.

TOM: It’s the battery equivalent of eating a couple of double-cheese-and-bean enchiladas.

RAY: Out-gassing usually is an indication that the battery is on its last legs. It often signifies that you’ve got a dead or dying cell, which in turn means the battery is putting out 10 volts, or 9.5 volts, instead of the usual 12. That’s not enough to start the car reliably.

TOM: And unless you’re parking on the beach, the fact that the corrosion came back just weeks after you cleaned it suggests that there’s a whole lot of out-gassing going on. My guess is that it’s time for a new battery.

RAY: But it can be checked. Have someone test the battery and charging system for you, and if you need another battery after five or six years, it wouldn’t surprise me.

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