I finally stumbled on some info for the Shell RV20 controller, kind of. It looks like they were made for Shell by Specialty Concepts Inc. and pic shows it is extremely similar to their Mark 15 controller
Mine:
They had/have a Mark 20 and a Mark 22. Here is manual fro 15/20:
Mark15/20A little strange mine does not have the "Charged" LED so hopefully just a cost savings on the LED and not that it does not recognize when full and change its logic. Mine automatically toggles between array amps and voltage so no switch. I cant seem to find a pic of the 20 or 22 so maybe one of these is a more direct match.
Some of the info I found suggests there might be a pot on the back of my panel to adjust the solar output voltage so will look for that and hopefully bump it up to about 14.4 volts.
Will see if Specialty Concepts can provide a manual for the Shell RV20 for further clarification.
