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Re: Alternator diodes

To: mgs@autox.team.net
Subject: Re: Alternator diodes
From: Florrie & Allen Bachelder <bachldrs@swva.net>
Date: Tue, 15 Jun 1999 07:25:37 -0400
When I bought my '67 a couple of years ago, it was wired positive earth -
as is appropriate for that vintage.  It sat for a couple of weeks before I
got around to running it.  Battery dead.  Put the trickle charger on.
Popped the breaker in the charger.  Checked with the voltmeter - sure
enough, the POLARITY on this battery was reversed.  No diodes to fry, but
the tach didn't work, and the field windings on the generator toasted also.
Didn't hurt the voltage regulator.  Solution: put on another gen,
repolarized it, rewired the tach, and replaced the battery - negative
ground this time.

Don't know how but it CAN happen - batteries can become repolarized.
Believe I've heard that they have to be completely discharged first, then
accidental polarity reversal on charging will stick - but only for awhile.
Reversed battery will not hold a charge very well/very long.

2¢...

Allen

From: dresden@tiac.net
>
>>In a message dated 6/11/99 2:06:39 PM SA Eastern Standard Time,
>>larryhoy@cwix.com writes:
>>
>>> Can incorrect wiring in the car cause diodes in the alternator to fail?
>>>
>>>  Larry Hoy

>>The only think that I can think of off the top of my head that will cause the
>>diodes to fail is connecting the battery backward...


******************************************
         Allen H. Bachelder  =iii=<
         Sinking Creek Home for Wayward MGs
         New Castle, VA 24127
         USA
         540/544-7333
******************************************



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