Connecting the towed battery to the 12 v house system

[mikestock]

I made a fused jumper to connect along side of the regular tail light system. I ran + and - to the starter battery to be sure I had a good constant ground. I ran the same type fused jumper from my house panel to the back of the rv and have a 5 foot jumper to connect the two when towing. I added this because I added a Patriot electric braking system and wanted to be sure I didn't rune the towed battery down while towing.

My question is: should i install some sort of diode in the system to isolate the towed battery so that the current only can flow from the motor home to the towed and not vice versa? I always heard it was a bad idea to parallel different systems.

[RoyB]

I would look into the smart charging relays over the diode based isolators...

Todays charging schemes and diode based isolators doesn't mix well due to the built-in voltage drops of diodes...

Roy Ken

[wolfe10]

I see no reason for a diode-- that is unless you are dry camping and forget to unplug the charge wire.

And if you decide to use a diode, make sure it is not a standard one that "charges" around .7 VDC. That much of a drop will render the charge wire pretty well useless.

[mikestock]

enblethen wrote:
A standard diode like this would work.
Diode

That is actually the one I was looking at. My concern was that if, by some chance, there was a large differential between the towed voltage and the RV voltage if it would handle the current surge that could occur. Probably a foolish concern.

There is a relatively inexpensive device on the market that will compare the voltage between the house and chassis batteries. It allows spill over to the chassis batteries if they drop too low while you are plugged in to a power source. I don't remember what it is called.

[enblethen]

A standard diode like this would work.
Diode

[petrel]

some sort of battery isolater should do the trick. There is quite a selection of them on the marine market, I'm guessing the same goes for RVs.