Posted 2019-05-21 4:47 PM (#582382) Subject: Leaking (!!) Voltage Regulator
Location: Sioux Center, IA
When I rebuilt my '61 Newport, I put in a new alternator (NAPA part 231-2012, a part with lots of Mopar applications) and upgraded to an electronic voltage regulator (NAPA VR38SB), which entailed a bit of re-wiring. All was well for 3 years or so. Last August, I noticed goo on the inner fender--the regulator was leaking. Its insulation or matrix (whatever it's called) seems to have begun to melt. The regulator was working. I replaced it, but the new one is beginning to do the same thing. What's up?
I tested the voltage at the battery--12.3 v when not running. Starting it up, the voltage went up to 15v; revving the engine backed it off to 14.6 or so. Is the alternator overcharging?
Other relevant info? I use a charger/maintainer when the car is not in use, but I have an isolation switch that cuts power from the battery to everything.
One regulator is a bad one; two in a row means another problem?
Thanks in advance for any advice on this great forum!
Posted 2019-05-22 1:06 AM (#582402 - in reply to #582382) Subject: Re: Leaking (!!) Voltage Regulator
Board Moderator & Exner Expert 10K+
Location: Southern Sweden - Sturkö island
actually, you downgraded to a yellow electronic voltage regulator.
I helped a guy with a 300G who changed 3 of those in one day. I had an old voltage regulator, mounted it and it's still working after 3 years.
Posted 2019-05-22 1:34 PM (#582411 - in reply to #582405) Subject: RE: Leaking (!!) Voltage Regulator
I agree, 14.6V is perfect.
The newer style solid-state regulators are well known to ooze the potting compound, doesn't hurt the function but makes a mess and probably shortens the life. Instead of mounting the regulator directly to the firewall, some models used a bracket that allows air to circulate under it.
Posted 2019-05-22 5:02 PM (#582420 - in reply to #582382) Subject: Re: Leaking (!!) Voltage Regulator
Location: Kalispell, MT USA
Maybe adding a heat sink to the front of the unit would make it run cooler. Some heat sink compound and a metal strap of some kind?
I wonder if an old computer CPU heat sink would be about the right size...
Posted 2019-05-22 5:22 PM (#582426 - in reply to #582382) Subject: Re: Leaking (!!) Voltage Regulator
Location: Sioux Center, IA
These are very helpful comments! I am happy to learn that 1) the substance is called "potting material"; 2) its ooze is not a sign of imminent failure and is common; 3) my alternator is within range; 4) that newer is not always better.
I like the idea of a bracket or heat sink to manage the problem; digging out the old regulator is my fallback plan. Happy for more ideas or experiences if you they are out there. I will report back when I have made any changes.
Posted 2019-07-02 6:13 PM (#584359 - in reply to #582382) Subject: Re: Leaking (!!) Voltage Regulator
Location: Perth Australia
To my knowledge they dont make solid state regulators for a generator
Generator regs control both field and armature current (reverse current)
Alternator regs just control field current. Field current = up to 5 amps (both alternator and generator around the same)
Armature current = 20-30 amps
The do make transistors big enough to cover armature current (amps) but they are big and will get very hot
The diodes in an alternator not only change the ac output of the alternator to dc but also eradicate the need for reverse current regulation
The diodes are mounted on a large heat sink in the alternator (or its case) and is air cooled (fan on the front)
Just to keep it simple, alternators and generators both have field coils and power windings. On a generator, the field coils are mounted on the case (stationary) and the power
windings rotate (armature), in an alternator, this is reversed so its the field coil that spins and power windings are stationary
This is why generator brushed are much larger than alternator brushes, its the vast difference in current they have to handle