Auto Clinic: Extend Your Car's Battery Life, Is Your Engine Guzzling Oil? and More

The Heat Is On

Q: My battery failed after four years, which I thought was a little too soon. The repair shop that installed it thought the same, so they replaced the battery with a somewhat larger one, the biggest they could get to fit into the battery tray. They also did a full charging system checkout. Two years later the new battery failed, so they replaced it under warranty--but only half the cost was covered. It seems the fine print in the battery warranty says the battery price is prorated. And after two years, I was responsible for the use I had of it until it failed. They installed a new battery identical to the previous one. It lasted only 18 months. So, of course, I had to pay again. I feel like I’m renting these batteries. What’s going on?

A: Normally, I suggest replacing the smallish standard battery with the largest one possible. This is a textbook example of someone honestly attempting to improve something, then screwing it up. I see it a lot.

Your original battery had enough room surrounding it for a simple plastic insulating blanket. This device is intended not only to keep your battery warm on cold nights--which it does--but also to keep the battery cool on hot days. Modern cars restrict the amount of air flowing through the engine compartment to improve both aerodynamic efficiency and economy. New engine compartments are pretty crowded. The elevated temperatures are enough to boil the electrolyte right out of the battery--hence, the simple insulator. Installing a bigger battery means there is no room for the insulation, which translates to short battery life, especially in warmer climates. You should try to rig up some insulation for your new battery, or at least replace the giant battery with one that permits the insulator to be reinstalled.

This is one of the reasons some cars have batteries installed in the trunk instead of underhood.