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Back With more charging woes #2842096
11/05/20 12:01 PM
11/05/20 12:01 PM
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Mesa, Arizona
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dart4forte Offline OP
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I’m having an overcharging problem. Here’s what I have

74 Dodge D100 with a 318
Running a Power Master 90 amp alternator. Changed the main power wire to 8 gauge
Rewired underdash wiring eliminating the amp meter using the MAD diagram
Wired in a volt meter wired off a 12 volt keyed source
Running an MSD 6A
Running a fresh VR that’s grounded to the black
Ground straps from the frame to the block and from the frame to the core support
Running Crackback HL relay kit
Did an overall check of the wiring and it’s pretty solid

What’s happening is when the truck is started it shows a charge of 13.5 volts on both the gauge and my ohm meter.

After giving it a few blips of the gas the gauge and the meter jumps up to 14.5 volts to 15.5 volts with the needle on the gauge jumping back and forth. It also shows a fluctuation on the ohm meter with the same results. Also shows the same at the battery.

I’ve striped off all the tape from the VR wires which the wires appear to be ok. Jiggled the wires and no change.

I mounted my spare alternator and have the same results. I’ve replaced the VR with several spares I have and have the same results.

Also to note the lights also flicker in tune with the needle on the volt meter. Lights don’t flicker at idle.

I unhooked the HL relay and went back to stock, no change.


Any suggestions?


“So if it’s on the internet it must be true”

Abe Lincoln
Re: Back With more charging woes [Re: dart4forte] #2842102
11/05/20 12:18 PM
11/05/20 12:18 PM
Joined: Nov 2003
Posts: 10,228
Colleyville
3hundred Offline
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Try a different, known to be good battery. Long shot, but easy.


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Re: Back With more charging woes [Re: 3hundred] #2842106
11/05/20 12:34 PM
11/05/20 12:34 PM
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5thAve Offline
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What does the VR plug and wiring look like? I've seen where something wrong with that will cause issues.

Since everything goes thru the dash volt meter is it worthwhile bypassing that to get it out of the picture? That's more of a question then comment. I know they can cause problems but don't know if that would cause this one.

Re: Back With more charging woes [Re: 3hundred] #2842116
11/05/20 12:55 PM
11/05/20 12:55 PM
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Posts: 16,117
Mesa, Arizona
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dart4forte Offline OP
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Originally Posted by 3hundred
Try a different, known to be good battery. Long shot, but easy.



Had the battery checked at two different places. Checked out good.


“So if it’s on the internet it must be true”

Abe Lincoln
Re: Back With more charging woes [Re: 5thAve] #2842120
11/05/20 01:00 PM
11/05/20 01:00 PM
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Posts: 16,117
Mesa, Arizona
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dart4forte Offline OP
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Originally Posted by 5thAve
What does the VR plug and wiring look like? I've seen where something wrong with that will cause issues.

Since everything goes thru the dash volt meter is it worthwhile bypassing that to get it out of the picture? That's more of a question then comment. I know they can cause problems but don't know if that would cause this one.


Did that yesterday. Dis connected the voltmeter and checked with my ohm meter. No change


“So if it’s on the internet it must be true”

Abe Lincoln
Re: Back With more charging woes [Re: dart4forte] #2842133
11/05/20 01:21 PM
11/05/20 01:21 PM
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Posts: 16,117
Mesa, Arizona
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dart4forte Offline OP
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If I convert to a one wire configuration would that eliminate all the stock wiring from the VR? One the red wire from the VR, it runs off a pig tail across to the ballast resistor which I have jumped due to the MSD.

Last edited by dart4forte; 11/05/20 01:24 PM.

“So if it’s on the internet it must be true”

Abe Lincoln
Re: Back With more charging woes [Re: dart4forte] #2842414
11/06/20 03:17 AM
11/06/20 03:17 AM
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Oregon
hooziewhatsit Offline
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Using a voltmeter, measure between the positive on the battery, and the blue field wire at the alternator. This should be close to 0v. If it's higher, something between the two has higher resistance and is causing the voltage drop, so the alt/regulator are regulating them selves to the proper voltage, causing over-voltage at the battery.


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Re: Back With more charging woes [Re: hooziewhatsit] #2842432
11/06/20 07:53 AM
11/06/20 07:53 AM
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North Dakota
6PakBee Offline
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Originally Posted by hooziewhatsit
Using a voltmeter, measure between the positive on the battery, and the blue field wire at the alternator. This should be close to 0v. If it's higher, something between the two has higher resistance and is causing the voltage drop, so the alt/regulator are regulating them selves to the proper voltage, causing over-voltage at the battery.


Good suggestion but I would check the voltage on the blue wire at the regulator as that is the reference voltage the regulator is using. Theoretically the voltage at the alternator would be the same as that at the regulator (still talking blue wire) but there may be a harness problem. The statement that when the engine is started the voltage is fine but after a few blips (and the resulting engine movement) the voltage is high leads me to suspect a bad connection. Shoot, it could be a problem with the plug on the regulator. Just have to cover all the bases.


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Re: Back With more charging woes [Re: 6PakBee] #2842509
11/06/20 11:38 AM
11/06/20 11:38 AM
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Posts: 16,117
Mesa, Arizona
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dart4forte Offline OP
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Originally Posted by 6PakBee
Originally Posted by hooziewhatsit
Using a voltmeter, measure between the positive on the battery, and the blue field wire at the alternator. This should be close to 0v. If it's higher, something between the two has higher resistance and is causing the voltage drop, so the alt/regulator are regulating them selves to the proper voltage, causing over-voltage at the battery.


Good suggestion but I would check the voltage on the blue wire at the regulator as that is the reference voltage the regulator is using. Theoretically the voltage at the alternator would be the same as that at the regulator (still talking blue wire) but there may be a harness problem. The statement that when the engine is started the voltage is fine but after a few blips (and the resulting engine movement) the voltage is high leads me to suspect a bad connection. Shoot, it could be a problem with the plug on the regulator. Just have to cover all the bases.


Good suggestions however I replaced the plug and wires alternator to VR. All the volt readings are consistent with one another. Fluxuates between 14 volts and 15.5. I even tested the small red wire in the harness going from the plug for the ballistic resistor to the Red VR wire. Once I get the alternator back I can go from there. As a note I installed my spare alternator yesterday day checked possible bulkhead connection problems. No corrosion in the connections, wiggled the connections while the engine was running with no change.

Did I mention I hate wiring?


“So if it’s on the internet it must be true”

Abe Lincoln
Re: Back With more charging woes [Re: dart4forte] #2857497
12/09/20 08:51 AM
12/09/20 08:51 AM
Joined: Jul 2007
Posts: 2,554
Maryland
wally426ci Offline
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Any updates? Same setup and I am getting random spikes while driving. If the VR was gone, I would think it would just climb all of the time....

Re: Back With more charging woes [Re: wally426ci] #2857525
12/09/20 10:04 AM
12/09/20 10:04 AM
Joined: Feb 2003
Posts: 16,117
Mesa, Arizona
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dart4forte Offline OP
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Originally Posted by wally426ci
Any updates? Same setup and I am getting random spikes while driving. If the VR was gone, I would think it would just climb all of the time....



Yes, here’s what I ended up doing. I converted My 95 amp Powermaster to a one wire. In addition, since the tech was inside the alternator he converted it to a 75 amp.

I removed all the wiring along the firewall that had anything to do with the old charging system. I had previously modified the wiring going into and out of the bulkhead connector which eliminated the amp gauge. Used the MAD modification. Also, I tossed the fuseable links and replaced them with circuit breakers. Simple parts that cost about $30 at Orielys.

I installed one of Crackedback HL relay kits.

Now, the truck idles at 14 amps and cruises at 14.5 amps. With the lights on it idles between 13.5 and 14 amps and cruises around 14.5 amps. The HLs do not dim and my dash lights are bright.

Now that my electrical has been sorted out I’ll start dabbling with the Sniper FI I have sitting on the shelf.


“So if it’s on the internet it must be true”

Abe Lincoln
Re: Back With more charging woes [Re: dart4forte] #2857732
12/09/20 05:29 PM
12/09/20 05:29 PM
Joined: Jul 2007
Posts: 2,554
Maryland
wally426ci Offline
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Posts: 2,554
Maryland
Nice! Thank you for the update.







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