A good alternative for the SURE Battery separator would be the BLUE SEA SI ACR model which will do the same type of functions as the SURE model.
This monitors the charge status of the second battery and will switch it in and out depending on the settings. When your truck battery is being charged by the truck alternator so will the second battery. Then it will switch the second batteries away from the alternator when being used. This insures the truck start battery is never in the second battery circuit when being used.
All of this is designed to switch out the truck start battery and not run down the truck battery.
I am going to do something like this with my setup by having split battery banks, one in the truck bed and the other bank on the trailer tongue.
My setup will allow the truck alternator to charge the truck bed batteries or I can do some BLUE SEA switching and allow the trailer converter/charger set charge the truck bed batteries.
This is just a study thing right now but will be looking something like this diagram... When I hook up my trailer I will connect up the 7-way cable and also the 2-pair 4AWG battery pair like shown in the second floor plan pictorial drawing.. Doing this will combine the two battery banks for the trailer operations (600AH Battery Capacity).
I am hoping to use 150AH TROJAN T-1275 12VDC batteries in both banks.
My next investigation will be if the truck alternator is large enough to handle the additional batteries. My back-up plan would be to charge the truck bed batteries using a B&D VEC1093DBD smart mode battery charger using the 2KW Generator for power source when the truck is being used by itself.
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