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Discussion Starter · #1 ·
I have an internally regulated 100amp alternator that works fine when you fire up the car (14V), but when everything heats up it drops to between 12.1V and 12.5V. This is not good with the fuel injection system which wants at least 13.5V. Is there any way to cool this better? It's too hot to touch.
Thanks
Wilbur
 

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Are you sure that nothing draws lots of amps when everything heats up? Check your amp draw.

When my radiator electric fans (two) go on, the voltage drops under 14V. I also have an internally regulated alternator (1 wire). On the other hand, my alternator does not get that hot. At least, I did not notice... I have a sb400 with headers, etc.

Theo.
 

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Where are you measuring the voltage at?
You could either be getting low output or voltage drop or using more than you are making. Measure the voltage AT THE ALTERNATOR between output and case! You do need to measure the output current also. You can get a cheap inductive semi inaccurage gage for ~$20. What about belt slip?
Mark
 

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Discussion Starter · #4 ·
The voltage gage is connected to the first junction right off the battery. My fuel injection system plugs directly into a laptop, it is reading the same voltage, so I'm assuming the reading is correct. I have a Windstar electric fan setup, only the smaller fan is running when this occurs, the engine temp is less than 200 (verified by gage and the computer) so the second fan hasn't kicked in yet. No lights on, stereo off, should be minimal load. No belt slip- I have an idler pulley to adjust the tension- it's tight.
Good suggestion on checking the amperage draw. I will get a gage and check, but that will have to wait a bit- I just pulled the motor to replace the short block. I will repost with an update when I get it running again.
Thanks to all.
Wilbur
 
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