I am planning a similar mod to my OFF-ROAD POPUP TRAILER where I want to have two locations for my battery banks. One Bank on my trailer and one Bank in the bed of my truck.
I am planning on using the TROJAN 12VDC 150AH T-1275 Deep Cycle batteries...
The Battery bank on the trailer will be a standard installation as I have been using additional batteries on the trailer tongue area for some time.
The Trojan T-1275 banks will each produce 300AHs. I have been running three 12VDC 85AH standard issue GP24 Interstate since late 2008 giving me 255AHs of capacity and have learned very well what needs to be done camping off the power grid using most of my trailer appliances etc... This does not include the Air Conditoner or high wattage Microwave but just about everything gets used.
Being a Ham Radio guy I have a need for a dual requirement for use of my radios. When camping it mostly for the hobby but being involved with Emergency Radio Operations I also seem to go a few alerts and need to have a bigger portable 12VDC operation out of my stand-alone truck.
I want to parallel both these 300AH battery banks when we are in camping mode using the BLUE SEA 4-position HIGH CURRENT rotary DC switches. My PD9260C on-board 60AMP Smart Mode Converter/charger will have to charge both battery when connected. This may have to be upgraded to the PD9280 (80AMP model) as my style of camping off the power grid works best if I can re-charge the batteries in a quick three hour time frame running my on-board converter/charger from my 2KW Honda generator.
When running the truck in its stand-alone setup I am planning on using the BLUE SEA 7650 SI-ACR Smart Solenoid unit installed on the truck side to use the truck alternator system to charge both the truck start battery and the additional 300AH battery bank. The smart solenoid will only charge the additional batteries whenever the Truck Alternator system goes into 14.4VDC boost charge mode. This connection will keep the truck start battery isolated from the battery bank until the the truck goes into boost charge mode and is suppose to keep battery bank high loads from running down the truck start battery.
This is the somewhat the same idea your friend did for you except this is automated and not manual operated like yours is being done. I have used the smart mode solenoids before for other projects. In the old days we could get away with DIODE BASED isolators but you can't do that anymore since the smart mode charging techniques have bee introduced. The high current DIODEs have too much voltage drop across them...
Something like this - ignore the 110Ah rating on the batteries shown - this should now read 150Ah...
My OFF-ROAD POPUP trailer floorplan looks like something like this
All still in the planning waiting for me to come up with the battery replacements first...
Roy Ken
