Bad Battery in a Jeep?

Bad Battery in a Jeep?

Jennifer has had a couple of episodes of her battery being dead when she comes back to her Jeep lately. It has been because she has left something on in the Jeep draining the power but really the battery should have had enough reserve to handle the load.

I suggested she take it to a local chain parts store to have the battery tested thinking that the battery may still be under warranty. They first informed her that the battery was out of warranty.

They proceeded to “test” it and told her not only was the battery bad but so was her alternator. I told her to drive it the short distance to her home and I would check it later. I would come and jump start her if necessary.

I was in the process of pulling the alternator from a parts car when I remembered that the alternator should throw an error code if it is bad. I called her and she confirmed that there was no check engine light. I left the alternator in place.

The next day, I took a spare battery and swapped it into place. In the process, I noticed that one of her battery terminals was very corroded. The spare battery performed about the same as her battery had in starting the Jeep and running the head lights.

I checked the voltage. On either battery, the voltage was just over 12 with the lights on. With the engine running it jumped to 14.5 or so indicating that the alternator was doing exactly what it should be doing. I noticed that the spare battery lost voltage faster than her battery with the engine off.

I swapped back to her original battery and cleaned the battery posts with a battery post brush. I also cleaned the negative terminal and replaced the corroded positive cable. Her Jeep now starts up briskly. The voltage gage on the dash reads slightly higher as well.

We will have to watch it for a few days, but I suspect her battery troubles are cured.