Isolator

Hi,

It is in place to prevent the "house" battery from draining the chassis battery. When the RV is running it allows current to recharge the house battery.

You really should look to see if your ISOLATOR is RELAY (SOLENOID) based or DIODE BASED.

Back in my early JEEP OFF-ROADING days we used a brick size three port DIODE BASED ISOLATOR to keep the AUXILIARY BATTERY isolated from the START BATTERY. This worked great back in those days and was very popular.

TYPICAL DIODE BASED ISOLATOR


TYPICAL SMART RELAY/SOLENOID SEPERATOR/ISOLATOR


In todays modern BATTERY CHARGING using SMART MODE Charging techniques where BULK MODE is 14.4VDC, ABSORPTION MODE is 13.6VDC and FLOAT MODE is 13.2VDC to quickly charge your deep cycle AUXILIARY batteries does not work well when you are using a high current DIODE BASED ISOLATORS. The VOLTAGE DROP across these high current diodes will drop the required 14.4VDC down to 13.7VDC so you are effectively not presenting the required 14.4VDC when in SMART MODE charging. This will charge your auxiliary batteries but will take much longer time to do it. Using SMART SOLENOID RELAYS solves this problem very well by switching in the relay to parallel the AUXILIARY BATTERY with the START BATTERY automatically when charging is required.

Here is a neat explanation article that explains this process pretty well.



AUXILIARY BATTERY ISOLATORs

Lots of info on GOOGLE SEARCH for these applications.

Roy Ken