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Old 01-14-2010, 11:53 AM
tr1cky tr1cky is offline
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Join Date: Sep 2006
Posts: 298
Quote:
Originally Posted by chev View Post
Re: '78 300d, 150Kmi DD

I recently had to replace my alternator (again) after 2 years on the previous AZone reman. (I know, I know... Bosch OEM is the preferred replacement), but since I originally replaced the one that's been in there since I bought the car in 1991, with an AZ part, ten years ago and it's warrantied for life, I couldn't help myself! If only they were self-installing...
Anyway, I'm already on that bandwagon.

After the previous alt failed ( 2 years ago) and was replaced, I also replaced the battery about a year ago.

Now with this third alternator-which charged at around 13.7-14.1 volts- last month the car again failed to start. I tried to charge the battery with my 10 amp charger. After an overnight charge, there still wasn't enough current to start the vehicle. I also noticed at that point that there was no apparent hydrogen outgassing.
I took it back to Interstate Battery, and they kept it for the long Holiday weekend-providing me with a loaner. They called, and told me that the battery had taken a charge and was ok, and we swapped the loaner.
Last night, I again had a nearly dead battery.

My question is this: if, as I suspect, one or more of the diodes were bad on the old (previous) alternator, can the resulting un-rectified electricity damage an otherwise good battery? I think it may be discharging internally.

I charged it overnight and I'm now showing voltages around 13.5-14 volts while engine is running, and do not have a charge warning light on the dash as I did when the previous alternators failed.

I've also checked to see if there is any major current drain with the key off, and, other than during the (wonderful Chrysler) A/C servo parking itself, there does not seem to be any major current flow. There is a small current drain, but I think it's just the clock. I'll find the appropriate fuse and see if I can eliminate that as a possible cause, next.

As a side question, are OEM diode packs still available for these, and where? I kept my first defective (original??) alternator rather than turning it in for core, in case OEM parts were available, and I wasn't satisfied with the AZ rebuilds. I used to diagnose and repair my Dodge Ram van alternators years ago, and parts were readily available back then, and it was really easy.
Is the voltage regulator part of that alternator?

Unrelated scenario, but this Summer I spent many hours diagnosing similar battery kills, starter solenoid destruction and high voltage. What I had assumed to be a faulty voltage regulator and rectifier was not the case at all. It was a tad bit of corrosion on the negative battery cable that was causing enough resistance to push the voltage up to a dangerous level. Snip and crimp and problem solved.
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