No more than 12.5 charging-Has to be VR problem?

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DemonK9

DemonK9

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First off, I would like to start by saying I have researched and read a lot of posts about charging issues in the forums. I find the posts by 67dart273 to be more than helpful & thank him for his genius and knowledge in this area! especially the posts when helping Robj with his issues.

My setup/configuration:
>'73 Duster
>New Ultra AGM Battery (tests at 12.69 volts)
>New Alternator (dual field terminal)
>New Painless wiring harness (Thus eliminating amp meter & bulkhead connection issues)
>Volt meter installed to a Ignition run wire
>GM HEI Ignition mod

I have performed the multiple tests and have found a basic 12.48 to 12.58 throughout the system, from key on/engine off to engine running at fast idle. Have found from a .3 to .7 volt loss/drop when checking loss/drop.

Cleaned up grounding points for VR, alternator grounded at VR attached point, engine block grounded to frame, battery grounded to block & frame. I have even tested with a ground wire running from VR/Alternator ground point to battery negative.

I have 3 extra Voltage Regulators laying around plus the one installed in car, so a total of 4. Upon installing the extra 3 VR's I get charging from 12.5 Volts and at fast idle/revving up motor, all 3 allow charging into the danger zone of 16-18+ Volts....so I know the alternator is GOOD as these VR's are bad/junk and let the alternator attempt to overcharge/cook battery.
The 4th VR, when installed, will only allow 12.48 to 12.58 output from charging stud on alternator to battery even with load (lights on)....and Volt meter gauge in car stays at just over 12 V.

I went for a test spin with the "4th" VR installed for about 20-30 mins to see if the volts dropped (thus running off of just battery) and the volt meter gauge stays pretty constant at 12 V or just over. Car starts with no problem after test spin & battery tests back at 12.38 - 12.46.

My question after all this babbling is:
Can the 4th VR be "bad" in the form of not allowing more than 12.48 to 12.58 volts into charging circuit?

I am going to buy 1 or 2 new VR's Monday. Napa is my closest retailer, so will try and get an Echlin VR (as they seem to be the most reliable).

Thanks in advance for anyone's input/advice!
 
The voltage too low is an odd one. Just for grins did you double check voltage with a different multimeter with fresh batteries? For sanity it would be handy to swap your "bad" vrs with another car.

There are only a couple wires to make it work. Should be able to make a jumper harness 1 wire at a time. Once ruled out the most probable, the impossible becomes suspect. I would run a clean wire to the switched power on as well. Ground the alternator case to the VR case.

http://i1271.photobucket.com/albums...rnal_voltage_regulator_wiring_zps8df13fa4.jpg
 
Toss the 4th regulator, and fix the voltage drop between the battery and IGN supply that feeds the regulator. See what voltage you measure between battery +, and IGN (Blue wire). That is your drop, at idle it is reducing the field current, at higher speed overvoltage. The 16 to 18V will cook the battery.
 
Vreg regulates the drop from IGN1 at the Vreg wire to its case. It tries to keep that at ~14 V. If you measure close to that, the Vreg is doing its job. You then need to find where the voltage drops are from its IGN1 to your voltmeter and its case to your voltmeter gnd.

Usually when there are voltage drops, Vreg overcharges the battery, so your results are a mystery. It sounds like your alternator is not outputting current, since sounds like your measured voltage drops when the engine is running. Does your dash ammeter work?

I have a clamp-on DC ammeter I use in testing to measure alternator output. Before that, I would wire in a series 100A ammeter for testing, i.e. in my cars w/o a factory ammeter. If not hard-core, buy a cheap cigarette lighter voltmeter (Harbor Freight, Amazon). In all my cars, I see >13.5 V when running, if the alternator works.
 
KitCarlson said:
Toss the 4th regulator, and fix the voltage drop between the battery and IGN supply that feeds the regulator. See what voltage you measure between battery +, and IGN (Blue wire). That is your drop, at idle it is reducing the field current, at higher speed overvoltage. The 16 to 18V will cook the battery.
Click to expand...


Between Batt + and IGN (blue) - Reading is .03 and once had .02

Guess we will see what a new voltage regulator does tomm night.
 
DemonK9 said:
Between Batt + and IGN (blue) - Reading is .03 and once had .02
Click to expand...

That seems wrong unless you are doing the test with car off, your other prior tests suggest a few volts. Are you measuring running, above idle speed where you were measuring 16 to 18V?

Another good test is battery - to regulator case, and again at engine ground to see if there are drops there.
 
KitCarlson said:
That seems wrong unless you are doing the test with car off, your other prior tests suggest a few volts. Are you measuring running, above idle speed where you were measuring 16 to 18V?

Another good test is battery - to regulator case, and again at engine ground to see if there are drops there.
Click to expand...


Yes....running above idle gave me the 16 to 18 V
 
Well, had a few long 14 hr days at work, so I didnt get to testing on the mopar for a few days.

I decided to take part of Trojmn advise about running new wires, so this is what I did:

>Disconnected the VR PLUG (the triangle shaped connector)
>Made up 2 new wires for the VR.....1 for Ignition and 1 for Field with connectors at both ends.
>Ran the corresponding wires to their respective places (1 from VR to one of the spade terminals on alternator <usually the GREEN wire> AND other from remaining connector on VR to the "blue" wire)
>This rewiring test I performed is to rule out a broken wire poor connection in the VR PLUG itself.


I fired up the mopar and tada, the source of the problem is found to be most likely the plug itself and/or wiring from the plug!

I regained a normal reading of about 13.6 Volts at resting idle and 14.86 Volts at high RPM.
Thanks to all that responded to my post and to all the Abody members for their posts in this forum about related electrical issues and how to test for problems!

For reference, this is the VR plug that caused my issue
 

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Woot!!!!!!!!!!!

I'm sure you got it from here, but since where in a testing mood... round pin terminals suck! pay close attention to the sizing of the female end. Sometimes they need a bit of gentle "reforming" to make and keep a tight connection.
 
Rice Nuker said:
Cool thread. Thanks for sharing. Where did that plug come from? I mean, where did you buy that plug and what is it called?
Click to expand...


It is called a Voltage Regulator Connector/Pigtail....some list it as a Voltage Regulator Socket. I picked mine up at my local Napa......but you can find them at almost any reliable parts store.....Summit racing has them as well.

I just dont like that the replacement only comes with about 3 inches of wire....means you have to have another connection to extend wires to wire them into proper locations.
 
Yep, which is why re-forming the round contacts has its appeal: no added connections/splices. Hopefully, you soldered and heatshrick wrapped the 2 new splices.

Regardless, good deal that it is fixed!
 
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