low voltage/battery charging issue
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New User
Joined: Sep 2012
Posts: 2
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From: Salt Lake City
low voltage/battery charging issue
I have 77 F250 ranger with a 5.8 modified engine. I installed a new wiring harness from Centech. It has a new battery, alternator and voltage regulator as well. It starts and runs like a champ but the battery isn't getting charged. I had the new alternator and regulator tested and they were good. My voltage gauge stays around 11.5 - 12. but eventually drops and I have to charge the battery. The alternator puts out 15.5v when they tested it, I can only get 12.2 right at the alternator and at the battery why it's running. is this a ground problem? I added a ground from the block to the chassis and that helped a little but the bat keeps dying. Any ideas what my prob could be?
-first time poster here, I've learned a ton from everyone on here! you guys are great!
-first time poster here, I've learned a ton from everyone on here! you guys are great!
Senior User
Joined: Oct 2012
Posts: 197
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From: Dublin CA
First off, clean the surface where you have your voltage regulator mounted. It needs a clean ground surface. Hook up your volt meter on battery charge back wire behind the alternator and ground. Disconnect the voltage regulator plug. Jump "I" terminal to "F" terminal on the plug. Start engine, and check voltage. Only do this for as little time as possible. Your full fielding the alternator, and pumping in 12 volts, where it normally takes 6 volts. If your charging ok, then its your regulator. If your not charging, then its your alternator and or related wiring.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Let's make sure the voltage regulator is even getting powered up first. Assuming this truck does not have an ammeter, check the voltage at the wire going to the 'I' terminal of the voltage regulator with the key in RUN. Report your results.
And while you're at it, please describe how you have the alternator and regulator wired up.
And while you're at it, please describe how you have the alternator and regulator wired up.
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New User
Joined: Sep 2012
Posts: 2
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From: Salt Lake City
thanks for the help guys
I ended up taking my truck "JoAnn" into the shop here. The problem was the wire from my voltage regulator to my alternator needed to be spliced and connected to the little screw on the starter solenoid. The VR needed an exciter wire between itself and the alternator. All is good, running at 13.5-14v now!
$65 bill was worth it being done, now I can go Coyote hunting!
Thanks again
~Dustin
$65 bill was worth it being done, now I can go Coyote hunting!
Thanks again
~Dustin
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