Schizo Alternator?

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Thu 1 Aug 2002 16:29
Schizo Alternator? - Mikeb
This problem is intermittent and has been going on for about a month.

The alternator and battery both checked out fine on a test stand at the shop so I'm confused.

While idling, the battery voltage is 12V but drops to 10V after some time or right after stop and go driving.

At 2500 RPM the terminals read about 13.5V

The tachometer jumps around a lot while driving. Sometimes when I hit the brakes, the radio goes off, but not always.

Anyone have a diagnosis?
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Thu 1 Aug 2002 18:19
Schizo Alternator? - SjB {P}
Poor quality earthing, probably with a loose connection, and resultant high contact resistance, given your description. of movement being involved.

Could also be a dry joint on a circuit board.
This was the cause of a similar problem I once had with a previous car. After a lot of time tracking it down, I found that the circult board with the voltage regulator was flexing with vibration and bodyshell movement just enough to make and break a solder joint on it. Heating the joint with a soldering iron to make it flow and re-set solved the problem.


/Steve
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