is the battery any good? a weak battery will cause an alternator to overwork and get hot. resistance in the battey cables, is the ground cable at the block and chasis clean or is there paint causing a bad connection. is the alternator rated to handle the electrical load of the cars accesories. fan, ignition, etc.
The alternator could be shorting out internally causing heat. I got a new one for my chevy and it was junk from the start. I blame junk chinese parts.
If all the rest mentioned is OK , you might just have a bad alt . Just because they are new doesn't mean they are OK . You could have a bad alt. that just keeps overcharging and doesn't shut down . If that is the problem you could have cooked the battery too . Take it off and have it checked at the local parts store or where you bought it . Retro Jim
Connect a volt meter to the out put on the back of the alt. It should read around 14.2 volts.If it reads down around 13 volts its charging at a high rate of amperage. Amps means heat think ark welder. If system voltage does not rise to 14+ volts after running for 15-20 minuets the battery may be bad.
Bad grounds happen when you forget to scrape off the paint where the bracket meets the block, and at the alternator as well.
Went through a similar situation with one of those Power Gen units. Called manufacturer and they said tighten the belt more because it was slipping and it would cause that situation. I was skeptical, but did what they suggested and it solved the problem.
How hot is it getting? They can get pretty warm and still be OK. Check the voltage at the output of the alternator, and also measure the voltage between the body of the alternator and the GROUND side of the battery. Any voltage reading there above a very small fraction of a volt will indicate a bad ground. I thought the ark was made of wood?
Make sure the belt is proper for the pulleys being used. If the belt is running in the bottom of the pulley it will slip, oftentimes without any noise, and heat the pulley and the alternator to the point a diode can/will fail. A belt must run on the sidewall of the pulley, not down in the bottom of the groove.
How much current is it putting out? Alternators are around 35% efficient, if it's charging at 80A x 14V that's 1.12kW, Which means its actually taking over 3kW of power, so a little less than 2kW is wasted heat. That's about 6800Btu/hr.
Some info I found on a non-traditional thread: In case anyone is curious about this issue, I came up with some temperature data: The owner of a 2001 Legacy told me that he measured his alternator at 220F with an infrared themometer. Another individual says that the maxium rated temperature is 239F. These units DO get hot, fast.
Ditto, the ground.... and ditto "stellar". I have one of the "generator" style alternators, from Speedway....Got hot as he** , so I added a heavy ground lead to the engine block, it runs a lot cooler now. Yes, they do tend to run on the "warm" side ! 4TTRUK
I hate 1 wire alternators, since they are RPM excited there isn't much you can do about the heat besides checking your connections and making sure your wiring is up to snuff. Even a 3 wire alternator is really as simple as hooking up two wires. The field can be jumped off the battery lead and the exciter just needs to be tapped into an ign source (coil wire, AC comp wire, sometimes even the wiper motor has a ign switched 12 volt)
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