intermittent alternator charging

intermittent alternator charging

Postby doomytunes [OP] » January 5th 2020, 2:22am

Hello all!

I've been using this site a lot over the last few months as I convert a 1995 AWD Astro into a covert camper and it has been an immense help. I got a good 6000 miles in over the past 2.5 months until it all started coming apart...

As I was driving one night, my blinkers started flashing very slowly and I noticed the voltage dropping from its usual spot between 13-14 down to about 9 volts over about 5 minutes. As it got that low the engine started to backfire and die and as I was slowly rolling over the rumble strips on the side of the highway, it suddenly jumped back to normal voltage and continued driving as usual. Drove okay for a day and then started to do it again. Pulled into O'Reillys and they said the alternator and battery looked fine, but the voltage regulator was bad. I replaced the full alternator and now sometimes it charges, sometimes it doesn't. When it's working, im getting 14.5 volts registering on the gauge and at the battery, and about 11.5 when it's not. Sometimes I start it and it doesn't charge at all, sometimes it does for 20 minutes then drops down again.

The strange thing is that when it's low, I put a voltmeter on the battery terminals and get 11.5, but if I put one end on the alternator B+ and the other on a ground or on the battery neg, it shows 14.5 volts, so I don't think the new alternator is bad (but I could very well be wrong). Is this a symptom of a bad voltage regulator still, or does it sound like the fusible link between the two is bad? I have been trying to find that link and am having trouble tracking it down too...

Any help would be very appreciated! Thanks in advance!

Jack
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Re: intermittent alternator charging

Postby chevymaher » January 5th 2020, 3:31am

Heavy wire going from the alt. Look for a fuseable link. It is fried. Should be one between the alt and battery.
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Re: intermittent alternator charging

Postby N6KB » January 5th 2020, 7:26am

Regulators have been built in to the alternator since at least the late sixties. Pretty much not serviceable except for replacing the whole alternator. From your voltage measurement directly at the alternator I would say there is nothing wrong with it. There is something wrong with the wiring between the alternator and the rest of the system. A loose connection or bad fuseable link as Chevymaher said.
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Re: intermittent alternator charging

Postby doomytunes [OP] » January 5th 2020, 4:01pm

That's just what I was thinking too. I'll swap it out and get back to you guys. Thanks for the quick replys!
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Re: intermittent alternator charging

Postby AstroWill » January 9th 2020, 10:54pm

Check/clean/tighten your connections at the back of the alternator, down at the starter, at the battery, and where the negative attaches to the body.

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Re: intermittent alternator charging

Postby doomytunes [OP] » January 16th 2020, 8:13pm

It worked! Fusible link was bad. thanks for the help everyone.
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Re: intermittent alternator charging

Postby AstroWill » January 17th 2020, 2:32am

Awesome, glad you got it fixed!

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