Battery level / Charging issue
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Battery level / Charging issue
I just bought a 1974 F-350 with a 302 in-line 6 in it. I have replaced the starter (which was grinding), starter silonoid*, alternator, voltage regulator, ignition coil, ignition switch, and battery but I am still having a problem with my battery getting a strong charge. While my pick up is running my battery reads 12.64V to start off then slowly goes down. Once I turn dome light and exterior lights on the battery rapidly decreases and obviously eventually dies killing my truck. I thought it was a short but my battery doesn’t die when pick up is off completely, etc. I also cleaned every ground off and added one to the frame from the body, which is grounded twice by the motor. I am not sure how exactly everything should be wired for all the systems to work properly and can’t find a reliable diagram online if that’s the case. I have ran out of ideas on what could be the reasoning behind this load of malarkey. Hopefully some of you guys can help me out.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Yep, sounds like it isn't charging. Here's some tests:
http://www.aa1car.com/library/battery_runs_down.htm
http://www.aa1car.com/library/battery_runs_down.htm
Moderator & parts slinger
Joined: Feb 2007
Posts: 50,158
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From: S/W Missouri, Polk county
So new alternator, but was it bench tested BEFORE is went out the parts house door? You know new in box, does not always mean good to go part.
Or yes you have something wired up wrong.
Some wiring diagrams here. https://www.ford-trucks.com/forums/1...l#post14696846
And troubleshooting here. https://www.ford-trucks.com/forums/1...l#post14880906
More. https://www.ford-trucks.com/forums/1...l#post15918103
Or yes you have something wired up wrong.
Some wiring diagrams here. https://www.ford-trucks.com/forums/1...l#post14696846
And troubleshooting here. https://www.ford-trucks.com/forums/1...l#post14880906
More. https://www.ford-trucks.com/forums/1...l#post15918103
Cargo Master
Joined: Nov 2011
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From: Great American SouthWest
The battery, at rest, should be 12.7
The system, when charging, should be around 14
At 1500 rpm, you should see charge voltage.
Possibly your voltage regulator. It's basically a switch to turn the alternator on and off. They can be bad, but can also be easily jumpered for testing the alternator.
With the VR jumpered, the alternator will be in "full output 14+ volts". Use the jumper sparingly! If it's not, your problem could be the alternator.
But it could also be a wiring issue. I'd start by looking at the VR
The system, when charging, should be around 14
At 1500 rpm, you should see charge voltage.
Possibly your voltage regulator. It's basically a switch to turn the alternator on and off. They can be bad, but can also be easily jumpered for testing the alternator.
With the VR jumpered, the alternator will be in "full output 14+ volts". Use the jumper sparingly! If it's not, your problem could be the alternator.
But it could also be a wiring issue. I'd start by looking at the VR
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I put in a new alternator and voltage regulator already the regular was drawing my battery with vehicle off so I got a new one and fixed that problem. I think I tried jumping it before like you are saying but nothing happened. I’ll have to try again or make sure it’s sll hooked up right. Thanks for the diagrams. Also no I have not tested the brand new napa alternator. I originally got it thinking it was shorting out but the new one hasn’t seemed to make a change... I did test my old alternator though and it tested bad but that surprised me. Perhaps I got a bad new napa alternator but I rather not think so.
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Lead Driver
Joined: Jul 2017
Posts: 9,591
Likes: 1,171
From: San Jose, CA
Lots of instances of the wires put back on the alternator incorrectly. Or the large Black charge wire could have failed. I don't have a stock one anymore, so forget if it's got a fusible link or not. But if it does it could be suspect.
You can easily test the connector on the voltage regulator to see if things are as expected.
Does your truck's instrument panel have an ammeter? Or just a charge indicator lamp? I'm guessing an ammeter because not only did most come that way, but you didn't say anything about a red light being on when the engine is running.
If an ammeter, the Green w/red "S" wire should have 12v when the key is in the RUN position.
The Yellow "A" wire should have full battery voltage all the time.
The Orange (or whatever color yours is) "F" field wire will have varying readings so not worth testing at this point.
But you can test the Field wire with an ohm-meter.
Did you know to bolt the regulator to the body before you attach the wires? Doing the opposite can fry an otherwise perfectly good regulator.
Good luck.
Paul
You can easily test the connector on the voltage regulator to see if things are as expected.
Does your truck's instrument panel have an ammeter? Or just a charge indicator lamp? I'm guessing an ammeter because not only did most come that way, but you didn't say anything about a red light being on when the engine is running.
If an ammeter, the Green w/red "S" wire should have 12v when the key is in the RUN position.
The Yellow "A" wire should have full battery voltage all the time.
The Orange (or whatever color yours is) "F" field wire will have varying readings so not worth testing at this point.
But you can test the Field wire with an ohm-meter.
Did you know to bolt the regulator to the body before you attach the wires? Doing the opposite can fry an otherwise perfectly good regulator.
Good luck.
Paul
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Success!
Paul I just got home from figuring out the problem and you were just about there! I looked back over the diagram of an alternator some one posted and it said something about the alternator indicator light being out shorts the circuit or whatever. So looking at the other diagram somoeone posted of the chassis electrical I traced the red and green wire on the voltage regulator to the alternator indicator, (WHICH I THEN BI-PASSED) back to the blue wire going into the ignition module. And bam. Alternator now charges battery at 13.5V with lights on. I will have to add a resistor since I jumped the alternator indicator according to that alternator diagram but for now I’m happy and couldn’t have figured that out with out y’all help. Thanks guys
Lead Driver
Joined: Jul 2017
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From: San Jose, CA
Hey, a good result from some hard fiddly work it sounds like! I actually meant to say Green w/red (not Red w/green, which is for the ignition system) but whatever you did got it closer at least.
That 13.5v is not great, but since that was under load then you at least know that it's for sure charging the battery. Just not at a quick rate. As someone mentioned, you would optimally want to see about 14.5 at the battery with the engine running. But 13.5 still gets the battery charged.
Anyway, glad you got it handled for now. Interested to hear more about what you do with the resistor when you're done
I know we say something is "only temporary" but I like to add to that that it's only temporary "unless it works!"
Oh, and this may indicate something wrong with your circuit at the gauge cluster.
The resistor is there to act as an alternate path for power if the light bulb burns out. Did you try just replacing the bulb to see if that helped?
Paul
That 13.5v is not great, but since that was under load then you at least know that it's for sure charging the battery. Just not at a quick rate. As someone mentioned, you would optimally want to see about 14.5 at the battery with the engine running. But 13.5 still gets the battery charged.
Anyway, glad you got it handled for now. Interested to hear more about what you do with the resistor when you're done
I know we say something is "only temporary" but I like to add to that that it's only temporary "unless it works!"
Oh, and this may indicate something wrong with your circuit at the gauge cluster.
The resistor is there to act as an alternate path for power if the light bulb burns out. Did you try just replacing the bulb to see if that helped?
Paul
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