No Charge
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Senior User
Joined: Feb 2003
Posts: 395
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From: South Carolina
No Charge
After three brand new alternators, two new voltage regulators, a new battery and a wiring harness from a parts truck that I know had a good charging system, I still have no charge going to the battery. I had the alt checked at the parts store and it is definitely charging. Just not making it back to the battery for some reason. What should I check next? What could still be keeping the battery from being charged? From all of the diagrams that I've seen here, it's wired correctly. What to do?
All specs for the truck are in the signature link below. Thanks.
All specs for the truck are in the signature link below. Thanks.
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Joined: Jan 2001
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From: Virginia
You need to tell us what you have checked, and what are the symptoms.
What voltage do you get at the battery with the truck off, and then with the truck running?
Or are you diagnosing the problem as in a no start condition? And is it overnight it won't start, or it won't start after a couple of days?
What voltage do you get at the battery with the truck off, and then with the truck running?
Or are you diagnosing the problem as in a no start condition? And is it overnight it won't start, or it won't start after a couple of days?
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Joined: Sep 2003
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maybe you have grounding problems. If the battery is grounded to the frame, do you have grounding straps from the motor to the frame. Or if the battery is grounded to the body, do you have grounding straps from the motor to the body. Sometimes we tend to check voltages from one point to another and everything appears OK, but not check where we actually lose the circuit. Start with a good ground preferably at the battery post and check the positive 12V side at different points all the way from alternator back to the positive post.
A quick check for any resistance in the ground circuit could be to check the voltage from + to - at the battery and then check from the + battery post to ground at the alternator. There should not be much variance in the voltage reading. If its 1/2 volt or more, you have a grounding problem.
A quick check for any resistance in the ground circuit could be to check the voltage from + to - at the battery and then check from the + battery post to ground at the alternator. There should not be much variance in the voltage reading. If its 1/2 volt or more, you have a grounding problem.
New User
Joined: Dec 1999
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Just finished working on a '49 Ford car which has been having problems with the alternator working. It has a '78 302 with C4, etc, just recently put in. After many headaches, found that the main wire from the alt. (Blk/Org) had burned at the fuselink, and had broken in another place. Also found that the regulator HAD
to be grounded in order for the alt to start charging. This was found by a chance happening, as all other wires had been checked for voltage, had been checked for continuity, etc.
So, not only are all engine/frame grounds VERY important, don't overlook the quality of grounds to the body, which insure the functionality of the starter relay, AND the regulator!
Hope this helps somebody !!
to be grounded in order for the alt to start charging. This was found by a chance happening, as all other wires had been checked for voltage, had been checked for continuity, etc.
So, not only are all engine/frame grounds VERY important, don't overlook the quality of grounds to the body, which insure the functionality of the starter relay, AND the regulator!
Hope this helps somebody !!
Posting Guru
Joined: Aug 2002
Posts: 1,214
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From: Minneapolis, MN
The fusible link between the alternator and the starter relay is designed to protect the alternator in case of an overload. If the battery is connected backwards, even temporarily, the diodes in the alternator will allow full current to flow through the alternator. If the fusible link blows before the alternator gets damaged, just replace the fusible link.
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Senior User
Joined: Feb 2003
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From: South Carolina
Originally posted by oldcarbuff
maybe you have grounding problems. If the battery is grounded to the frame, do you have grounding straps from the motor to the frame. Or if the battery is grounded to the body, do you have grounding straps from the motor to the body. Sometimes we tend to check voltages from one point to another and everything appears OK, but not check where we actually lose the circuit. Start with a good ground preferably at the battery post and check the positive 12V side at different points all the way from alternator back to the positive post.
A quick check for any resistance in the ground circuit could be to check the voltage from + to - at the battery and then check from the + battery post to ground at the alternator. There should not be much variance in the voltage reading. If its 1/2 volt or more, you have a grounding problem.
maybe you have grounding problems. If the battery is grounded to the frame, do you have grounding straps from the motor to the frame. Or if the battery is grounded to the body, do you have grounding straps from the motor to the body. Sometimes we tend to check voltages from one point to another and everything appears OK, but not check where we actually lose the circuit. Start with a good ground preferably at the battery post and check the positive 12V side at different points all the way from alternator back to the positive post.
A quick check for any resistance in the ground circuit could be to check the voltage from + to - at the battery and then check from the + battery post to ground at the alternator. There should not be much variance in the voltage reading. If its 1/2 volt or more, you have a grounding problem.
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Posting Guru
Joined: Aug 2002
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From: Minneapolis, MN
Other than the cable from the battery to the block (or alternator bracket) there should be a ground cable/strap from the block to the body. Usually it's at the back of the engine to the firewall or part of the original ground cable fastened to the frame. Where ever it is there needs to be a good connection between the engine and the body/chassis.
Connectying the ground cable to a bracket will work as long as all of the connections are good. That means cleaning the paint off the bracket where the cable attaches and using a star washer, cleaning the paint from the bracket to block connection, etc. You get the idea.
Connectying the ground cable to a bracket will work as long as all of the connections are good. That means cleaning the paint off the bracket where the cable attaches and using a star washer, cleaning the paint from the bracket to block connection, etc. You get the idea.
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Joined: Jan 2001
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From: Virginia
You can do this voltage test.
Usually you will put the negative of the test light or meter, to ground, and then start poking around with the positive lead looking for voltage.
Instead, take the positive and hook it to the battery positive, and then start poking around at the sheetmetal and brackets with the ground lead. If you get low voltage or no voltage somewhere, you have a ground problem there.
Usually you will put the negative of the test light or meter, to ground, and then start poking around with the positive lead looking for voltage.
Instead, take the positive and hook it to the battery positive, and then start poking around at the sheetmetal and brackets with the ground lead. If you get low voltage or no voltage somewhere, you have a ground problem there.