100 amp dual voltage regulator putting out 15.3 volts on the 14 volt side

[AOR]

I did a bunch of searching and I have not located the specific information that I am looking for. I have a 100 amp alternator in my 1986 M998 with the dual voltage regulator that I assume was installed in 2007 when the Vehcile was overhauled in ME.
I spent of bunch of time and made a nice bracket and mounted my 12 volt side fuse block and breaker under the hood I guess I should have measured the voltage at the battery while the engine was running instead of in the run position before I started this project.
to keep confusion down here is what I am measuring at the batteries while running and my gauge does read in the green while running and I have not had any starting or charging issues.
These readings we taken at idle
28.5 running volts
15.3 running volts - rear battery

Does anyone know if the 100 amp voltage regulator is adjustable? I read that the 200 amp amp regulator Is not but I have not been able to confirm one way or the other on the 100 amp. I did find out that the 100 amp and 200 amp regulators mount in the opposite direction so I assume they are different.

I am curious what voltage readings that others have measured it would be nice to turn it down about .5 volts I am concerned about the 12 volt side putting out to much voltage and possibly damaging electronics



I think I read the specs on the 60 amp adjustment was 28 volts + or - .5 volts which puts 28.5 at the top end of factory specs

 

[mechanicjim]

if you want to find more info look at the name plates on the Alternator and Regulator. look for the 7676-N**** number, the N**** is the part number if it is a Niehoff they have some trouble shooting guides and such on their website. now to the voltage you are seeing is there any load on the 14V side of the system other than the battery? if not try adding a light and see if the voltage drops down. also the way the 14V is made is it "steals" from the 28V side capacity so see what the voltages are with all accessories on(lights, fan, ETC) to load the 28V side an see if the 14V comes down.