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Discussion Starter · #1 ·
I have just replaced my alternator and the new one gets extremely hot extremely fast. I timed it and the Alternator casing usually begins to heat up after two or three minuted at idle. I have replaced the main wire running to the battery and the harness that plaugs into the back of the alternator. It still continues to get hot really fast . Also, while driving my voltage meter reads "discharge" when I am either at a light or at a complete stop. What could be causing this alternator to heat up and not charge the battery properly? Thank you in advance for any replies
 

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Are you sure your alternator is spinning the right way? Also, there's a fan that attaches to the front of it that turns with the belt - it's to provide a minimal amount of cooling.

It sounds like your alternator could either be putting out too little, or too much voltage as well. Have you taken a voltage reading on the output post? I'd start there. Are you sure you didn't ground the alternator, that you have it hooked up to the correct post?

Are you running a single wire, or three wire? Are you using an internal or external voltage regulator?

Let's start there.
 

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Discussion Starter · #3 ·
It is a one wire alt. with a clip that plugs into the side, I think the alternator has an internal volt. regulator. I'm pretty sure its spinning the right way and I grounded it too. What should I check next?
 

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What's the output voltage?

What electrical loads are you running?

Maybe the alternator was bad our of the box. A shorted diode would make it act up like that except that a shorted diode should make it drain the battery with the engine off.

Peter
 

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Some alternator cooling fans are better then others, the SI-12 internal regulator alternators have a superior cooling fan then the SI-10. The fan on the SI-12 is a btter design and makes a better seal around the front of the alternator, its pulls allot more air through for cooling than the SI-10 type.
I have seen hi amperage alternators with the standard SI-10 fans, and wondered how the windings, diodes and voltage regulator were being cooled properly. The good fan almost looks flat sitting behind the pulley.
A 100 amp alternator at 12 volts could produce 1200 watts of heat, thats allot of heat in one small place, unless a good fan can reject the heat.
 

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Yeah, I'd definitely check the voltage output first, and list the electrical loads that are present on your car.

Also, does your battery die if it sits for periods of time? You could have a ground in your system somewhere as well, causing a large current draw.
 
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