New battery and alternator, still won't hold charge - Jeep Wrangler Forum

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Old 02-20-2013, 12:18 AM   #1
Join Date: Dec 2012
Location: Kennesaw, GA
Posts: 26
Question New battery and alternator, still won't hold charge

I was pulling out of my neighborhood the other day and as I hit the gas to pull into the roadway, it felt like the throttle just got choked out and the gauges were flipping all over the place. I managed to get it under control and I went to the Oreillys down the road from where I was. I told them what happened, we tested battery and alternator. Alt came back low. I order a new one then go home. I park jeep overnight then the next morning in remove alternator and go back to Oreillys to pick up "new" alternator and exchange old core.

Go home, install new alt and let jeep run. It stays low like 9V, I decide to hustle back to Oreillys but the voltage meter drops into the red and I have to keep the throttle going the whole time to make it. I can only make it to a walmart then it dies there. I remove 3yr old battery and have it load tested. It comes back bad this time, I get a new one. I install it, jeep starts right up, I go home.

By the next day, the meter is noticeably dropping again. I to oreillys, explain the situation, and have tests again. Alt coming in @ 11.8V and 20hr old battery @ 60%. Oreillys guy is clueless (thanks). I ask him about possible ECU failure, he doesn't know. I have been searching the web all day and I just want to make sure I'm heading in the right direction before I go blow $350. This is my DD so I need to get it resolved as inexpensive as possible. Any opinions or thoughts are welcome

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Old 02-20-2013, 12:58 AM   #2
PapaJammie's Avatar
Join Date: Apr 2012
Location: Southern Louisiana
Posts: 69
My dad's jeep had this problem before. It ended up being the ECM was bad, but one of the things I've heard you should check is the battery temperature sensor. If that goes bad, it can fool the computer into thinking the battery is overheating, so it stops charging.

The Jerp Is NEVER done

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Old 02-20-2013, 07:38 PM   #3

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Join Date: Dec 2009
Location: wichita falls texas
Posts: 1,035
you need to use a multi meter to see if you are having a drain on your battery with everything turned off and causing the problem .
Scott Howard
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