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Unread 01-02-2014, 07:01 AM   #1
highred
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1979 CJ7 
 
Join Date: Nov 2012
Location: Lake Lure, NC
Posts: 150
Alternator acting up

I put a new alternator in last summer. I couldn't tell you what size. It's what the kid at the parts store said the computer told him for a '79 CJ7. I'm not running any additional electric except for an alpine stereo with a 40 w amp. All of the lighting is LED.

I drive the Jeep daily and The problem I'm having is that the volt meter is around 10 when I start it up in the morning. It slowly builds up to 13 or 14 after 15 minutes or so, then starts spiking with the needle going completely off chart. Over 16. The lights get bright (head lights are not LED, everything else is), then go dim with the needle dropping to 12 or so.

So I'm not sure if this is the alternator or the battery, or something in between.

Any thoughts?

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Unread 01-02-2014, 07:36 AM   #2
JeepHammer
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1973 CJ5 
 
Join Date: Aug 2007
Location: South West Indiana
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Sounds like a bad voltage regulator.

This *CAN* Happen if the regulator isn't getting a good 'Ground' back to the battery, but that's unusual.
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Unread 01-02-2014, 08:07 AM   #3
EgulAye
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1980 CJ5 
 
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It sounds to me like the voltage regulator is not working properly, or something in that circuit (sense wire). I've seen quite a few discussions here on the forum about properly connecting the alternator and also on testing the circuits to determine where a problem lies. Good luck.
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Unread 01-02-2014, 08:29 AM   #4
highred
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1979 CJ7 
 
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Location: Lake Lure, NC
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Where's the voltage regulator? Is it in the Alternator? I have an HEI ignition which allowed me to remove the ignition box. So right now, my alternator is wired to the solenoid and battery. Pretty straight forward.
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Unread 01-02-2014, 08:34 AM   #5
JeepHammer
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1973 CJ5 
 
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'79, you have the standard Delco SI series alternator. It's built into the alternator.
Two wire plug in the side of the alternator, a bigger wire on the back of the alternator.
Pretty common stuff.
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Unread 01-02-2014, 12:39 PM   #6
86cj74.2L
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2004 WJ 
 
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Do you have a wire going from your negative post of your battery to both the engine block and a smaller wire going to the body beside the battery? Or just 1 wire to the block?
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Unread 01-02-2014, 04:22 PM   #7
highred
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1979 CJ7 
 
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Location: Lake Lure, NC
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Quote:
Originally Posted by 86cj74.2L View Post
Do you have a wire going from your negative post of your battery to both the engine block and a smaller wire going to the body beside the battery? Or just 1 wire to the block?
Both block and body are grounded.
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