My 83 d150 overcharged a battery. Seems to be a large voltage drop from VR to battery causing the overcharge and high 16V. I'm wondering about bypassing with relay from VR to battery. I've seen this talked about in some other forums but was hoping for some clear instructions,diagrams,pics or video links that anyone could share.
1983 dodge d150 overcharged battery
- Thread starter mwd782
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mopar56
Well-Known Member
Have you tried just replacing the voltage regulator? I have had a bunch of these trucks and not had that issue, seems it would just be better to correct the problem rather than patching it?
Voltage regulator is new. Alternator is new. Grounds are good. When just key turned VR reads 11.7V while battery reads 12.6 when truck is on the voltage just slowly rises in both battery and alternator. I'm thinking at this point the voltage drop from the old wiring between the VR and the battery is causing the alternator to run to high causing overcharge. I don't have the time to do a full rewiring at the moment and had seen on some forums people do a bypass trick. Like the pic below.
mopar56
Well-Known Member
The diagram seems simple enough, but I have not tried this before, I do know that some of the older Dodge trucks had issues with their ammeter ( wires melting at the back of the gauge ) just like the old A bodies but I don't recall the 83 using a ammeter I believe they were a voltmeter?
It depends on what is causing the drop. In other words, where is the resistance? If its in the ignition circuit, then the relay is a decent solution. If its in one of the power feeds, then IMO it is much better to fix the power feed. This all makes the assumption that the '83 D150 is wired with a main splice under the dash where the power feeds all join.
It's also possible the alternator field to regulator wire is grounded (pinched or brush terminal insulator missing)
To find the where the resistance is.
Before doing this, slow charge the battery if its low.
1) get a wiring diagram, and/or look over your vehicle to see if the battery line, and the alternator output go through the firewall and join with the circuitfeeds under the dash. I think trucks still were wired like that in 83 but dont know for sure.
2) Engine off, measure voltage at battery and at alternator output. Should be the same. Should be at least 12.5 Volts.
+ turn on lights, read ammeter, and check the voltage at the battery positive and the alternator output. Then do a direct measurement of the votlage difference between the battery positive and the alternator stud. That's the voltage drop in the battery line to the main splice for X amps (whatever you read on the ammeter).
If there is a voltage difference to ground that is more than the direct voltage drop measurement, then there is resistance in the grounding.
3) Engine running. Read the ammeter. Measure the voltage at the alternator output, the battery positive, the regulator input (ign terminal).
The voltage at all three should be the same. Voltage differnces between the alternator output and the ign terminal of the regulator indicate resistance between those two points. If the alt and bat voltages are the same, then the faults are probably downstream of the mainsplice. If the alt and bat voltages are different, then depending on the ammeter reading - we can estimate how bad the resistance is between those two points. If the battery feed to mainsplice was OK in the headlight test - engine off, then the fault is in the alternator's output wires and connections. That must be fixed.
It's also possible the alternator field to regulator wire is grounded (pinched or brush terminal insulator missing)
To find the where the resistance is.
Before doing this, slow charge the battery if its low.
1) get a wiring diagram, and/or look over your vehicle to see if the battery line, and the alternator output go through the firewall and join with the circuitfeeds under the dash. I think trucks still were wired like that in 83 but dont know for sure.
2) Engine off, measure voltage at battery and at alternator output. Should be the same. Should be at least 12.5 Volts.
+ turn on lights, read ammeter, and check the voltage at the battery positive and the alternator output. Then do a direct measurement of the votlage difference between the battery positive and the alternator stud. That's the voltage drop in the battery line to the main splice for X amps (whatever you read on the ammeter).
If there is a voltage difference to ground that is more than the direct voltage drop measurement, then there is resistance in the grounding.
3) Engine running. Read the ammeter. Measure the voltage at the alternator output, the battery positive, the regulator input (ign terminal).
The voltage at all three should be the same. Voltage differnces between the alternator output and the ign terminal of the regulator indicate resistance between those two points. If the alt and bat voltages are the same, then the faults are probably downstream of the mainsplice. If the alt and bat voltages are different, then depending on the ammeter reading - we can estimate how bad the resistance is between those two points. If the battery feed to mainsplice was OK in the headlight test - engine off, then the fault is in the alternator's output wires and connections. That must be fixed.
67Dart273
Well-Known Member
I don't remember if an 83 pu has a "full current" ammeter or not. First thing to do is find some way--mirror, camera, small child, LOL and look up in the cluster and see if there is the usual "big red" and "big black" or not.
I've recommended relays for years, cut the "run" wire coming into the engine bay, use the firewall end to fire a relay, feed the relay off the starter relay with a breaker/ fuse, and connect engine bay end of the run wire to the switched contact.
I've recommended relays for years, cut the "run" wire coming into the engine bay, use the firewall end to fire a relay, feed the relay off the starter relay with a breaker/ fuse, and connect engine bay end of the run wire to the switched contact.
I had the same issue with my w250 last year and i was going to do the relay fix but i couldn't bring myself to cut the harness up so this is how i fixed it . mine was charging 18v so i cleaned all connections and the bulkhead connector ran a few ground wires and got it down to 14.7v . Then i got the adjustable Transpo VR and set it to 13.8v its been over a year now and it's still charging a rock solid 13.8 .
HD EXTERNAL VOLTAGE REGULATOR CHRYSLER DODGE PLYMOUTH 1970-1987 Transpo C8313 | eBay
HD EXTERNAL VOLTAGE REGULATOR CHRYSLER DODGE PLYMOUTH 1970-1987 Transpo C8313 | eBay
slantsixdan
=..=
Except it says "Body ground" where it should say "Good ground" (which means alternator housing or either end of the battery negative cable).
Ammeter through '89, voltmeter starting in '90 on the D/W-trucks. But it was a shunt-type ammeter (not subject to the wire-melt problem), not a full-current type like the pre-'76 A-bodies and pre-'71 B/C-body cars. Don't recall what year the trucks switched to shunt ammeters.
When off battery and alternator both at 12.5v
When key is on batt 12.04v alt 11.99v VR 11.56
When lights on batt 11.8v alt 11.7v VR 11.2v
When ignition on batt 13.2 and rising alt 13.3 and rising and VR at 11.7v
Thanks for all the help so far guys. If this looks like a voltage drop between battery and VR I'm going to probably do the bypass for now until I have the time to really get in there.
When key is on batt 12.04v alt 11.99v VR 11.56
When lights on batt 11.8v alt 11.7v VR 11.2v
When ignition on batt 13.2 and rising alt 13.3 and rising and VR at 11.7v
Thanks for all the help so far guys. If this looks like a voltage drop between battery and VR I'm going to probably do the bypass for now until I have the time to really get in there.
67Dart273
Well-Known Member
OK, that may not be "voltage drop." WHERE are you measuring this? If this is right at the battery, then it is the battery itself dropping, and 11.2 is LOW. Either the battery is not fully charged, or old or something wrong with the battery
"Voltage drop" which causes VR overcharge is caused by bad connections in the harness connectors/ terminals, the ammeter circuit (if it is full current), and the ignition switch itself
To test for this, turn key to "run", engine stopped
Stab one probe into the top of the battery POS and the other probe on the key side of the ballast resistor. You should read very little, and over .3V (3/10 of one volt) you should track further.
The ground path can do the same. To check that, run engine at simulated low/ medium cruise, IE fast idle. Make this check, first, with accessories off, and again with lights, heater, etc powered on
Stab one probe into the top of the battery NEG post. Stab the other---hard--into the VR mounting flange. The lower the better, zero is perfect.
worth a try better than cutting up your harness
Battery is brand new so scratch that off. Did the ground test already was at .03 at the voltage regulator mounting flange. so I gave it a good clean and it went down to 0 and maybe .01
When testing ballast resistor it reads 0.4v
When testing ballast resistor it reads 0.4v
67Dart273
Well-Known Member
A new battery (or any other component) does not mean "functions correctly." Even "new" batteries can have problems.
Those drop readings look great, so I don't know, might be worth "throwing" a different VR at it
Those drop readings look great, so I don't know, might be worth "throwing" a different VR at it
What's the ammeter show for those two readings?
There should be no difference in voltage from the alt (which acts like a probe to the main splice) to the regulator terminal because with the current in that circuit should be very low, like 5 amps.
Also. How are you measuring the voltage at the regulator? Are you piercing the wire? removing the plug?
With the engine running, Power supply at 13.3 V and voltage at regulator sensing terminal of 11.7 the resistance is probably in the column connector, key switch, or one or several of the connections in the ignition run wire.
So I tried the bypass. That didn't work. Ordered the new adjustable VR that didn't work either, voltage still rising and now white smoke from under the dash. I haven't adjusted the VR yet.
I'll go in this weekend and clean things up add more grounds etc.
Would it just be that the alternator isn't working? Any ideas?
I'll go in this weekend and clean things up add more grounds etc.
Would it just be that the alternator isn't working? Any ideas?
67Dart273
Well-Known Member
You need to learn to troubleshoot. Not trying to sound flippant or sarcastic. One question.......Do you know if this was ever the huge frame 105A alternator (way larger bracket, etc?) Some of those used a "field loads" relay and different wiring
For all others, the VR/ field circuit is such:
The wire at top marked "ignition" is the switched 12V "run" line that powers the ignition system and some other underhood loads. It is not only power to the VR but also the "sense" voltage. That voltage MUST not have voltage drop or the system will overcharge. It branches off and goes to one of the two field terminals on the alternator. The remaining field terminal comes back to the VR. The VR in effect controls "the amount of ground" or the current through the field to control the output. More current is more magnetism and therefore more output
You must determine if that circuit is correct. You must check field continuity at the alternator field terminals and be sure that NEITHER IS GROUNDED.
You must check for voltage drop either in the field / VR circuit or the ground circuit. For the VR/ hot side of the circuit, turn key to "run" with engine off. Stick a probe of your meter into the battery positive post, and the remaining probe as electrically close to the VR IGN terminal as you can get. This will likely be the key switch fed terminal of the ballast. You may be able to back probe the light blue at the alternator field, and you may have to switch the two field terminals of the alternator around to probe the blue. Does not matter which terminal the blue and green connect to
You can quickly tell if the VR has any control over the alternator by disconnecting the blue wire at the alternator
For all others, the VR/ field circuit is such:
The wire at top marked "ignition" is the switched 12V "run" line that powers the ignition system and some other underhood loads. It is not only power to the VR but also the "sense" voltage. That voltage MUST not have voltage drop or the system will overcharge. It branches off and goes to one of the two field terminals on the alternator. The remaining field terminal comes back to the VR. The VR in effect controls "the amount of ground" or the current through the field to control the output. More current is more magnetism and therefore more output
You must determine if that circuit is correct. You must check field continuity at the alternator field terminals and be sure that NEITHER IS GROUNDED.
You must check for voltage drop either in the field / VR circuit or the ground circuit. For the VR/ hot side of the circuit, turn key to "run" with engine off. Stick a probe of your meter into the battery positive post, and the remaining probe as electrically close to the VR IGN terminal as you can get. This will likely be the key switch fed terminal of the ballast. You may be able to back probe the light blue at the alternator field, and you may have to switch the two field terminals of the alternator around to probe the blue. Does not matter which terminal the blue and green connect to
You can quickly tell if the VR has any control over the alternator by disconnecting the blue wire at the alternator
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