Perhaps you can match up a GOOGLE IMAGEs picture...
ISOLATOR or SEPARATOR
In my Battery system combiner setup I am not able to use a DIODE BASED unit as the voltage drop across the diodes is about the same as the difference between SMART MODE BULK charging voltages and ABSORPTION charging voltages. For charging my deep cycle batteries I need to be using 14.4VDC-13.6VDC-13.2VDC charging voltages and if the ISOLATOR is a High Current DIODE based unit their internal voltage drop across the diodes will not be compatible with the required deep cycle battery charge voltages.
Make sure the BATTERY COMBINER is a smart solenoid relay item. Blue Sea and Sure Power Industries sell them on AMAZON...
I would suggest picking up a cheap MULTIMETER from WALMART-LOWES. They only cost $7-$20...
Harbor freight used to give you one for free with purchases.
If you want to get serious about troubleshooting your RV you really need to have one.
Just my observations
Roy Ken
My Posts are IMHO based on my experiences - Words in CAPS does not mean I am shouting
Roy - Carolyn
RETIRED DOAF/DON/DOD/CONTR RADIO TECH (42yrs)
K9PHT (Since 1957) 146.52M
2010 F150, 5.4,3:73 Gears,SCab
2008 Starcraft 14RT EU2000i GEN
2005 Flagstaff 8528RESS