lonnwood wrote:

During the last 2 ground test runs my voltage has been
creeping lower. It started out at 14.2 volts but now it is
around 13.5.  It is from an 87 RX7.
What are the failure modes on these?
Do I just need to change the internal regulator or is there
any testing I can do first?
Lonnie

        Lonnie,

          I ran into a similar situation with my 88 RX7. Battery voltage

would

 gradually go low. I was convinced the alternator was the

culprit(130,000 miles)

 so I had it rebuilt. After installation I had the same result. I would

charge

 the battery but after a day or two of driving to the airport the

voltage would

 gradually go low. I finally did what I should have done in the first

place. I

 had the battery load tested which showed a bad cell. Apparently the

alternator

 could not charge through it. New battery(less than 1 year old,Free

replacement)

 and all works as it should. FWIW

      Kelly Troyer

I hooked up a digital ammeter yesterday. It is drawing 7 amps while running.
 I also hooked
up a hundred feet or so of 16 gauge wire across the battery to load test the
alternator. It showed an extra 30 amp draw without the voltage dropping.
Ran for about an hour, the voltage at one time drifted up to 14.2 v and then
back down to 13.7.  The only thing I can conclude is the regulator is a
bit flaky.
Lonnie

 
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