I am using the mechanical relay. The issue is that the wiring is OLD and there is just enough of a voltage drop to screw with the voltage regulator sensing properties.
It matters not if the regulator is mechanical or electronic. If the sense wire to the regulator is less than 12 volts, then either regulator will tell the alternator to up its output.
If I take the wire off of the VR from the switched ignition source and just jump it from the battery with full 12 volts, the regulator-alternator puts out a steady 14.2 volts which is in the range 13.7 to 14.3 of the service manual.
The problem is not what regulator type nor is it the alternator. It is the sensing of the voltage.
From: dplotkin@xxxxxxxxxxxxxxxxxxx <dplotkin@xxxxxxxxxxxxxxxxxxx>
What follows is subject to correction by John Grady.
Chrysler products using an alternator were designed to work well and did for millions of miles.
Over charging with non-original regulators is part and parcel of reproduced parts. The electronic versions all over charge in my experience, running around 15-16 volts at road speeds. I assume that this is intentional, that the makers figured better to overcharge than undercharge especially with a handful of cheap components lacking any precision. Flooded cell batteries don't really care as long as you add water. Gel and AGM batteries are less tolerant.
I understand the use of relays in working around crummy headlamp wires but I would stay away from that on the ignition or charging side. Good engineering where I came from is the use of the least amount of parts and complication possible.
The mechanical regulators are still available though not Mother Mopar manufactured. These can be adjusted if you are careful. The electronic versions, not. Find one before you fill your engine bay up with wires.
I have spent hours reading everything I could find on the subject and my conclusion is that over time even Chrysler had issues with this subject.
The change to both internally regulated alternators and the extensive use of relays were the result.
Apparently Dodge Motor homes were particularly susceptible to this problem due to the long wire runs and extra loads on the ignition system to accessories that were switched via the ignition key.
I could spend a week taking the entire dash apart, the dash harness, and the ignition wire through the bulkhead connector and replacing it with one larger size. Of course, that is a lot of work.
Alternately, I can use a relay in the engine bay and use the ignition wire to turn the relay on and off. That relay would then feed the 12v to the voltage regulator and to the ballast resistor 12v side.
The voltage regulator would then have a remote sensing point that is not having to deal any losses due to the age of the ignition wire, the contacts on the ignition switch or the bulkhead Packard connectors. The power for the coil, via the ballast resistor and any electronic ignition would also all be a full 12 volts.
If anyone has any thoughts, I would still like to hear them. But I suspect that a relay or two is in my future. I may also build a relay block for the headlights at some point.
PS. Do remember that this is for a MAIN daily driver. I am not building the 300K for concourse work.
From: 'James Douglas' via Chrysler 300 Club International
I suspect that this problem has been going on over the last month as I started driving the 300K but since I do not have a voltmeter on the car, I did not notice. Once off idle it starts to ramp up way past 14 volts.
I purchased one of those $10 USB things that plug into the cigar lighter. This one has a voltmeter built into it. That is when I noticed the overcharging the other day.
We spent a couple of hours trouble shooting. What is going on is that the wire from the starter switch through the bulkhead connector, then on to the voltage regulator is showing a ½ volt drop. We checked the resistance on the circuit, and it is not showing any issues. We even jumped the spades with the connector off of the starter switch and we get the same result.
What is happening is the reference voltage on the voltage regulator is 11.5 volts. That is causing the VR to tell the alternator to crank up and we end up getting 15 to 18 volts on the system.
What is interesting is the “orange box” of the ignition is placing enough load on the circuit to cause the issue. If we disconnect it that loss to about an 1/8 of a volt. It still should be 12 volts, or the VR reference will not be correct.
I have never had such a problem. I need to figure out how to deal with it. I suspect that if one was running points, it would not be an issue with the small loss of reference. But then again who knows as this car is new to me and it could have been cooking batteries for a long time.
Anyone ever run into this? I cannot conceive of this being related to the Power Master alternator.
My neighbor who used to work in auto electric work thinks the way to deal with it is to place a relay next to the VR to make sure it is getting its reference voltage at 12 volts and not rely on the dash wiring to supply it. Since at some point I may go to EFI, I will need a clean 12-volt source under a load that is switched in any event.
The only other option is to open up the entire wiring harness under the dash and replace the wire from the starter switch through the bulkhead connector up to the ballast resistor then on to the voltage regulator with a new wire.
I do not have the kind of tester to check the wire under a load to see if it is the section from the starter to the bulkhead, the bulkhead to the ballast resistor or from there to the VR.
Tired and going to get a drink.
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