[rich2468]

Hey Travis,
I have Lithium Ion Phosphate batteries in my TM and have towed for two years without a DC-to-DC charger. My tow vehicle (TV) has a "smart" alternator and my TrailManor batteries are located at the rear storage of my 2922KB....so the Lithium batteries work out to be about 36-38 feet from my TV battery. (considering the routing through the tow vehicle, over the Bargman wiring, connecting through the TrailManor's power converter, the Lithium battery shunt, then finally to the Lithium battery bank).

The distance from the tow vehicle's batteries via the Bargman to the area behind the Trailmanor's refrigerator where the two different (battery) direct current power sources (TV and TM) meet is probably around 26 to 28 feet from the tow vehicles's lead acid battery (over 10 guage wire). That mid-point connection also probably 10 feet from the Lithium battery bank after passing through the TM power center.

I use an OBDC bluetooth dongle to monitor various tow vehicle running parameters (engine & transmission temps along with charge voltage) and haven't noticed anything unusual in the tow vehicle alternator charge status due to having the TM Lithium batteries attached over the small wired Bargman connection (even when the TM battery bank has been discharged). I do see the tow vehicle alternator voltage jump up when turning on the TV's air conditioning systems (which is to be expected)....but I don't notice any unexpected behavior with the TrailManor connected. As previously stated I wired my power lead for the tow vehicle's Bargman connection with 10 guage wire.

I am in the middle of adding a DC-to-DC charger (with appropriate sized wiring and Anderson connections) as a separate connection from my tow vehicle to my TrailManor's
Lithium Ion Phosphate battery array due to the simple desire to keep my TM Dometic 3-way fridge running in DC mode while under tow for extended periods of time. The Victron Energy 18 amp DC-to-DC charger (with dedicated wiring and fusing) should allow me to arrive at all campsites with a cold fridge along with both my battery bank and propane tanks topped off.

Your situation is certainly different than mine-
Sounds like you're using propane for a refrigeration energy source under tow
I have no idea of you tow vehicle alternator/ vehicle capabilities
I don't know your budget constraints

If budget is not an issue, I'd suggest considering a DC-to-DC charger simply to allow you to potentially run your (stock) refrigerator via DC under tow and only worry about impacting your propane supply for boon docking refrigerator usage, water heating, and cooking (and supplemental heat if the diesel heater needs help).

I know that propane is cheap and that you're adding a diesel supplemental heater and I also think I recall that you're going to add solar. Solar is great (I have a kilowatt on my roof now), but solar won't add to your battery charge much on cloudy days or any at night. In my book DC-to-DC is a smart idea due to the limited weight and the ability to charge under any towing conditions. It also fits within my goal of not carrying along a generator and being able to perpetually boondock/ dry camp under reasonable conditions (even if those boondock campsites may only be in State and National Parks vs. BLM land).

Ironically, when I check the Amp rating of a small Honda (47lb) EU2200i inverter generator- I see that it's pretty identical to the Victron DC-to-DC charger that I'm installing. The generator is certainly more versatile at camp, but it won't help me while I'm under tow.