Me thinks my alternator is on crack

[xjc]

I bought a sami with a GM alternator, installed in a rather questionable manner but working fine until recently.

Here's the problem, When I start my samurai it starts cooking the smaller wire coming from the battery (runs everything but the starter). The trick is that is only happens a while after the motor is started. When the key is just"on" (motor not running) there is no problem.

DATA: Voltage at the battery doesn't change immediately when the motor is started, a few seconds after starting, the motor (for no apparent reason) starts sounding loaded and the voltage jumps from 12.5 or so to 14.5. The loading can only be the alternator (only auxiluary draw on the motor).

UPDATE

Mystery solved- but there is something not completely right. Turns out my battery was low, when I charged it the probem went away. Turns out the alternator was charging the batery way faster than the stock wiring was capable of. THis was made possible by two things
1. The alternator is a monster and can maintain very high amprige
2. It is cranking out 15V... EEEK may indeed be on crack

Please tell me if I am wrong but that's wrong isn't it?

 

[Rusted]

Did you put a volt meter on it while it was both running and not running? Is it really putting out 30 volts?

Is the battery giving you 12v while everything is shut off?

 

[xjc]

I didn't come up with my diagnosis until after I put the kid to bed last night and it doesn't have a muffler so I haven't checked the volted for sure yet. Its a dead give away.

 

[Kiel]

I have a gm alt on mine and thats the way they start. It doesn't start charging until it senses a load then mine kicks up to 14.5 from batt voltage. age from the batt. Then threw a huge inline fuse in it just in case

 

[xjc]

Good, I'm glad to hear that's normal. I will put a big fuse in and Ill have to figure out what I can do to eliminate this problem.

 

[Col Mustard]

Is the small wire the stock one? If so, you'll have to increase the gauge. The stock wire is rated to work with the stock alternator which has a much lower output. It's common to have to put a heavier gauge wire in when going to a higher output alternator. You'll have to measure the amps passing through the wire to be sure. You can't rely on measuring voltage alone.

 

[Kiel]

Is the small wire the stock one? If so, you'll have to increase the gauge. The stock wire is rated to work with the stock alternator which has a much lower output. It's common to have to put a heavier gauge wire in when going to a higher output alternator. You'll have to measure the amps passing through the wire to be sure. You can't rely on measuring voltage alone.

I did- works good But he is right I heard that wire has hit or miss success on being aboe to handle it, I put a fuse inline there also just in case

 

[xjc]

All right, so do I need to replace the wire that goes all the way to the fuze box or ECU and back or can I just run a big fat wire from the alternator up to the positiv for the battery?

 

[meanbgreen]

did ya see if the voltage regulator on the altenator is jacked up, most auto stores test em for free