70's Mopar Voltage Regulators

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The application is a 1976 Dodge grain truck, D 600 with a 360 2 barrel, 5 and 2, but the same regulator was pretty much used on everything Mopar from 1970 until the late 80's. Silly little silver or black box on the firewall with 2 wires attached.

My problem is this. The unit was replaced with the alternator about 2 yrs ago, but this fall it started periodically failing to charge the battery. I put the battery tester on one day last week and it was kicking out 16 volts. When the unit warmed up, it quit charging. I've cleaned cables and since it is capable of putting out 16 volts, I don't think the alternator ( it's a Bosche replacement) is at fault. On Wednesday I replaced the ignition switch ( it was feeling sticky, and supplies the power to the red wire going into the regulator) and the regulator with a new one from Wilson. Right off the hop, as soon as the engine fired at fast idle, it was booting out 16 volts ( or more, that's as high as my tester reads and it was pinned). My 2nd suspect would have been bulkhead connector if it was sending intermittent current to the regulator, but at this point, there was no vibration or movement or anything to trigger sketchy current to the regulator. I backed the truck outside and let it idle down off fast idle and the current relaxed to around 14.5. I kept the meter on while I was unloading the canola in the box, and just sitting at idle, the voltage would vary from 14 to 16 volts... so even brand new, this regulator wasn't controlling voltage as much as idle speed was. Looking online, I've found comments that the Chinese knockoffs are copies of the original 1970 patent, and that as soon as you put more amperage on the alternators, they fry... often in 2 days. Sounds familiar. I've found an AC Delco version with a 2 yr warranty for $36 Cdn., or an original Mopar unit for $75, but before I throw more money at it, is there anything I may have missed? Is there anything besides a voltage regulator that would cause the charging circuit to over charge? I'm thinking a short should affect amperage, but not voltage, and if I've run it for several hours, anything shorting out would have fried by now. Thoughts? I've also got a single wire Delco alternator in stock I could put on and leave the external regulator off, but I'm not sure if that would affect the ignition brain box.The harder you fall, the higher you bounce...250 amp Miller DialArc AC/DC StickF-225 amp Forney AC Stick230 amp Sears AC StickLincoln 180C MIGVictor Medalist 350 O/ACut 50 PlasmaLes
Reply:You could be having some ground bond problems, engine to body, body to battery, etc.
Reply:I'm not familiar with that brand equipment, but have worked a bit on similar systems. To check everything out, I'd first confirm that the battery was behaving normally, perhaps by disconnecting it and putting a good charger on (one I knew well) after it's been sitting a good while, to see how the charging current and voltage behaved. Then, with battery attached and key on, engine off, see how much current is being drawn from the battery. Maybe unplug the alternator and see if the draw changes much. Speaking of that, what kind/model/output alternator is it?Do you have a schematic for the (original) charging system?Is there a significant difference in measured voltage at the battery vs alternator output, while the engine runs?Wonder what would happen if you inserted a 10w variable resistor in the circuit to the alternator rotor (slip rings, and increased it from zero, while watching the output voltage? Maybe monitor the rotor circuit voltage too, to see if the regulator tried to compensate by raising the volts?I agree about always checking for good grounds on everything involved..Last edited by Oldiron2; 39 Minutes Ago at 03:11 AM.