Alternator or battery? -
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post #1 of 6 Old 07-22-2016, 07:41 PM Thread Starter
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2007 JK Wrangler 
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Location: memphis, tn
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Alternator or battery?

Several months ago, I started having a problem. I'd get in the Jeep... (2007 Wrangler) and everything was fine. As soon as I'd turn the key, it would click and everything shut down. I eventually replaced the battery (and one of the post clamps) and everything was fine. Occasionally it would happen again, but only rarely, and I could fix it by tightening the positive battery clamp... which always seemed to get loose...

This week, it happened again and no amount of tinkering with the posts helped. I could jump start the Jeep and it would run as long as the other battery was connected. I double checked that all the battery clamps were tight and still... nothing.

A guy at the NAPA store told me it sounded like the alternator. I changed the alternator, jumped the Jeep and ... as soon as I disconnected the battery it would die. Sigh...

Just on a lark (and because I was tired of messing with the old post clamps (quite corroded), I replaced both of the battery clamps and bingo! It's running like a champ...

I'm trying to convince myself that the alternator was causing the main problem and the battery (and its corroded clamps) were a secondary issue.

Did I waste money on the new alternator? I really can't do anything about it now, and I suppose it doesn't really matter, I'd just like to know...

Anyone else ever have this problem?


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post #2 of 6 Old 07-23-2016, 06:23 AM
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2006 TJ Wrangler 
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Location: Westchester, NY
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This sounds to me like a wire/clamp/ground issue. I'm not convinced it was either your alternator or your battery. Just in messing around with them enough you eventually stumbled on to the other problem and fixed it without realizing it.
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post #3 of 6 Old 07-23-2016, 07:33 AM
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Clicking and not starting is almost always a connection or wiring issue. The battery and the alternator can, and should, be Load Tested to determine if they require replacement. You need to find a shop or auto parts store that will bench test the parts for the best accuracy. Auto part store handheld in car testers often pass marginal batteries and weak alternators.

Testing the battery and alternator yourself in the driveway is not difficult or expensive. All you need is a $ 6 - 15 volts/ohms multi-meter. Load Testing is still very strongly recommended.

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post #4 of 6 Old 07-24-2016, 06:51 AM Thread Starter
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Yep. I was afraid of that... but no worries now. Now I know better AND I know how to change an alternator!!! SIgh...
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post #5 of 6 Old 08-09-2016, 11:55 AM
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2004 WJ 
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i had a buick that did the same thing. would only run when another battery was connected to it. Come to find out it was the fusable link. the issue, besides that, was something was shorting it out and we didnt know what it was.

2004 WJ,242tcase,255/75/17 Wranglers,UnidenCB w/4ft firestick. Member of RDJ
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post #6 of 6 Old 08-09-2016, 03:05 PM
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Pulling off a battery cable on a modern computer controlled car is a BIG NO NO.
With no ground thru the battery the computer wont have the ability to process info so the car will run.
So by doing that you prove nothing and run the risk of a voltage spike to your PCM.
The battery should be removed , charged and properly tested and the proper equipment should be used to test the charging system. Also if you used one of those cheap replacement cable ends you screwed up , don't be cheap replace the entire cable.
Computer control cars don't like to see voltage drops across the battery.

1995 2.5 5 Speed SOA +2.5 rough Country lift, High steer kit , 33x12.50 Mud Rovers
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alternator , battery , battery connection

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