CJ7 alternator upgrade?

CJ7 alternator upgrade?

JJs85cj

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Bogue Chitto, Ms
Vehicle(s)
1985 CJ7 258 in line six with the old JFI kit, T5 trans and dana 300 transfer case.
I need to go with a higher output alternator on my jeep. I just recently got the AC working and now with the fan running on high along with my stereo ( with 2 amps ) the volt meter drops down to less than 12v. Its so bad when I add a turn signal in the mix the radio and amps will shut down. Is their a junk yard swap to do this upgrade or should I fork out the money and buy a new one. If a new one any suggestions?
 
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Thanks! If 100amp do you think I will have to increase the wire size from alternator to battery or will the stock work?
 
I have also heard of having your stock alt. rewounded where they accully rewinded your alt. with more windings around the rotor which can jump it up to 100 amp idle and 140 amp higher rpm or driveing conditions. I've not looked into the cost which would be cheaper. I'll call a shop near by hear that we've been takeing alts, starters, and gens. to. I need to look into this my self cause I have a winch and stock alt. and sometimes when I use the winch the volt meter drops below 11. I'll call today at 9am centeral time. And post what I find. As for the stock wireing not sure but I believe your stock wiring will handle it. Maybe if you have the one wire alt.hook up like I do that may need to be upgraded on mine it looks like its about 12 or 10 gauge. Someone with more knowlege then I on the site will chime in. :xj:
 
Thanks! If 100amp do you think I will have to increase the wire size from alternator to battery or will the stock work?
At 100 amps you can use stock wiring.

I have also heard of having your stock alt. rewounded where they actually rewinded your alt. with more windings around the rotor which can jump it up to 100 amp idle and 140 amp higher rpm or driving conditions.
Thats a good idea. Its a rebuilt alternator. Low cost because they reuse most of the old alternator.
Avoid the one wire alternator. They cost more. The warning light on the dash won't work any more. Check out this link: Catalog
 
I got off the phone with shop and he said can rewind alt. to 50 idle 100 peak for $85. or use a mid 90s modle 75 idle 140 peak. at $140 inculding brackets and wireing adtapter. Or a powermaster high-output alt. for 80/140 at 156.99 for 1981-90 cjs and wranglers #pow47294 at www.4wd.com sorry about the bad info. So all depends on what you want or need you can also go for the mean green 100/200 starting at 418.99 on www.4wd.com but if you shop around you might find it cheaper. I'm running a winch. No extra lights so if a winch and lights are in your future this may be something to consiter don't want to have to upgrade twice. Just my 2 cents:)
 
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Another thing to consider is Heat Dissipation. The higher output alternators would have a case designed to dissipate the heat. While it is possible to have a rebuild shop up the output, it may not be the best move.
On boats we have using high output alternators for quite a while and found it important to consider the case size.
 
Thanks for the link busta. I will be staying with the 3 wire alternaltor after reading the article. I going to run by the local alternator repair shop and ask about rewiring mine to 100 amp. Also will ask about the overheating that may be involved in this up grade. If he thinks it going to be an issue with go with a new one. Thanks to all for the help. Hopefuly I can return the favor some day.
 
Part of your posting asked about amperage drop due to resistance and heat dissipation.

C.E. Niehoff Co. - Brushless Alternators - Commercial - Military - Mining - Construction

This link is for Niehoff Alternators, under tech tab, they have a voltage, amp / gauge wire chart that will give show what a 100 amp unit with 10 guage wire will only give you 84 amps after the loss due to heat, resistance and length of wire.

Of course this info is for their unit not your AC/Delco unit yet should give you an idea of what to expect.
 
Try this, it shows the recommended wire size for the voltage drop desired



Wire gauge color codes in these charts correspond to AWG wire sizes.
marinegraph2.png
 
Thanks 81laredo for the info saved to my jeep files for future refferance.:cool:
 
Just thought I'd let you guys know I when buy my local alternator shop Wensday. He said the alternator on my Jeep can not be upgraded. He's building me a 180 amp for $180.00 and install it for another $10.00. Again thanks for all the info.
 

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