House battery while hooked up

I learned when I checked out my new Ford F150 that Ford furnishes a relay that activates the voltage for charging the battery at the 7-way trailer wiring connector for vehicle equipped with the factory tow package.  I don't know if other mfrs have a similar relay that needs to be installed before the vehicle will provide this function.  Mine came in a plastic bag with a spare 7-pin connector and the installation instructions.

Using a volt meter, verify that you have 12VDC across pins #1 (ground) and #4 (battery charge).  On a Ford both are #10 gauge wire and will be sufficient to charge the battery on your trailer while the reefer is set on 12VDC.  Ours did!

Brian,

Prior to your purchase of the isolator, you might want to check out the solid state isolator by Hellroaring technologies (www.hellroaring.com).  I am new to the world of battery isolators but I understand from a review of isolators that both diode based isolators and relays have disadvantages compared to the new solid state type offered by Hellroaring (http://www.off-road.com/chevy/reviews/hellroaring/).  The biggest disadvantage of the diode based isolator appears to be voltage drop of about 0.8v.  That could reduce the capacity for battery charging. Hellroaring Technologies battery isolators/combiners can be mounted on the camper (http://www.hellroaring.com/rv.htm) without altering the tow vehicle's wiring.  I plan to look into their 75150 isolator for mounting on our Trailmanor.  The cost is ~$125, but I could switch tow vehicles and still have isolation.  Plus the wiring appears to be simpler.

Also, the wiring on our 3124 Trail manor the "hot" wire from the vehicle goes to the back of the trailer (with 10 ga wire, I presume to the converter)  and then returns via 12 ga wire to the battery.  I wonder if it would improve battery charging to have shorter circuit in series which would bypass the converter and go directly to the battery?

Any thoughts/suggestions would be welcome!

In my previous post I should have stated:  

 "I wonder if it would improve battery charging to have shorter circuit in parallel (not series) which would bypass the converter and go directly to the battery?

Just had an email reply from Mike Hines of Hellroaring Technologies.  

Their Battery Isolators/Combiners (BIC) do not require any compensation to the alternator and are compatible with all alternators.  When the voltage at the sensor terminal of the BIC rises above the typical no load voltage for a 12 v auto battery (~13.4v), the BIC switches on and illuminates an LED.  It switches off when the voltage drops to about 13.2v.  These voltages can be adjusted if they are not correct for a particular situation.  Additional LEDs allow one to evaluate the battery condition and charging status.

They suggest increaseing wire size to 8 AWG to improve charge rates but to provide circuit protection for the smallest wire (e.g. 40 amp fuse for 10 AWG).

Their web site outlines several configurations and a remote switch is available.  I like the on-camper configuration as I would never have to worry about switching tow vehicles.