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Old May 28, 2014 | 04:21 PM
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Alternator question

Im just looking to get some insight on my alternator. Ive been watching the voltage on my scangauge more closely since i noticed it dropped to 12.7v on saturday. Since ive owned the truck, i dont think ive ever seen over 13.8v. I know its not an original alt

I read voltage with my meter off the alternator stud and grounded to the case and got 13.8v (when scangauge was saying 13.2) and then i took the connector off the alt, filled it with dielectric grease and it was reading 14(at the scangauge). Now its all over the place, its been bouncing from 12.7 to 14.3v all day. Could this be a voltage regulator? Those are internal right?

If i do end up needing a new one, ill likely just get a 140amp upper alt off a dual alt truck
 
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Old May 28, 2014 | 05:56 PM
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The dielectric grease does nothing to help the connection, but it does help prevent corrosion. I don't think you fixed anything there.

It could be the voltage regulator or the alternator, and you can replace the regulator separately. But they're around $50 from Rockauto, and you might as well replace the whole unit for not much more than that.
 
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Old May 28, 2014 | 06:11 PM
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Yeah, i know, just mentioning the steps of what i did and what the results were

The 140AMP alt is only about $230 so thats not bad at all, this alt has a reman sticker on it so im sure its gonna give up soon anyways
 
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Old May 30, 2014 | 08:34 PM
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Had an hour drive home and the scangauge said 12.6-13.1 the entire drive home...got in the driveway and it was idling at 13v and read 13.7-.75 on each battery so i guess its charging fine. Just weird its reading so low on the scangauge
 
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Old May 30, 2014 | 09:02 PM
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Hrmmm...I *think* the Scangauge is measuring voltage at the OBD port rather than the PCM. Perhaps you have a connection that you're intermittently losing voltage over.
 
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Old May 30, 2014 | 09:03 PM
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wouldn't surprise me...lol
 
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Old May 30, 2014 | 09:17 PM
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With a good battery most ford trucks charge at about 14.3 to 14.5.. Regulator and brush kits are inexpensive. I think under 25 dollars on ebay...200 amp alternators are not that much either...I got an ambulance regulator which charges at 14.6 volts. Good for all my elect crap.
 
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