Thanks for your reply.
I believe there are two wires from the panel to the controller. On the roof the solar panel plugs into a two pin connector into the roof.
I have measured the voltage at this point and it is the same as going into the controller.
A pair of wires come out of the wall and into the controller which is a CMTP02 controller:
http://diyprojects.e...user-manual.pdf
I have said to ATC, a good panel with a ten dollar controller.....go figure.
When I first noticed this problems, ATC sent me another controller.
I think the controller they sent me was defective so I took the truck down to them and they installed another controller.
It seemed ok at their shop but not under real 'solar conditions', as the truck was not in the sun.
As I mentioned now Im back to the same problem.
At night the voltage drops down to 12.7 (with the frig plugged in and using some lighting).
{I should have mentioned the system has a battery isolator between the truck battery and the camper battery . It seems to get warm so Im wondering if the battery is back feeding into the isolator when parked and no engine on. }
I think it is the controller causing the problem.
so to recap: voltage in full sun off the battery : 16-17 v
at night 12.7v
This is read with a voltage meter off the battery....
When I pulled the fuse on the solar to the battery, I still had battery reading on the controller . when I disconnected the ground from the controller to the battery the controller went blank.
could this be back feeding to the controller through the battery ground?
With the solar disconnected from the battery it shows the same voltage going in and coming out of the controller. about 16+ volts....in low sunlight.
No solar battery now reads 12.7 v
tnx
Edited by 5outta6, 01 September 2019 - 02:14 PM.