Replaced alternator, still low voltage

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LEO 57
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  • 3 POSTS
Ford
F150
1998
160000
4.2 L

After the "battery" light came on, I had the alternator checked, which showed a bad alternator. I replaced the alternator, but the light was still on. I took it to the place of purchase and was told it was OK (test was done with the alternator on the truck). By the time I got home, the battery was dead. I had the alternator checked elsewhere, and the voltage was just over 12V. I took it off and went back to place of purchase and a bench test showed the alternator was OK, but no voltage readout was available. When I check the voltage with the engine running, it showed about 12.5 V at the battery. My problem is similar to that of Murdock1 posted Feb 16, 2007.

Any ideas on why the drop from the alternator to the battery?
Feb 17, 2007 at 3:56 AM
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SERVICE WRITER
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Sounds like a bad reman alternater that doesn't hold up under load.
Feb 17, 2007 at 7:28 AM
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LEO 57
  • MEMBER
  • 3 POSTS
Ford
F150
1998
160000
4.2 L

The alternator I bought was a Duragold DLG3506-16-2 and the description said it was all new, no reman. Is it a common problem for an alternator to test OK on the bench (presumably at no load) then not be able to produce adequate voltage on the vehicle?
Feb 17, 2007 at 2:12 PM
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SERVICE WRITER
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You would think if it is new it should be fine. I have seen many remans fail that shouldn't. Bench testing will show good, or worse yet, they are intermittant and somtimes pass and sometimes fail. If all of your connections are good, clean and tight, the battery handles a load test, then I would be highly suspicious of the alternater.

I'm not familiar with duragold, but if it an autozone product, I would even less faith in it.
Feb 17, 2007 at 10:39 PM
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SERVICE WRITER
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Glad to hear you found the problem! I guess I assumed fuses were already checked, but I should have asked.
Feb 18, 2007 at 12:03 PM
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