Battery disconnect

[Duramax1]

Yes, you are correct it would be more fool proof if the trailer brakes and breakaway switch were hot and ready to pull current even with the battery switch in the off position. I wonder how Heartland does the factory battery switches in the units that come with? I bet they did theirs just like I did mine other than they likely put their switch in the positive side rather than the negative side.

Yes I agree that I have to have my battery switch in the on position to safely tow so the breakaway switch can operate from the RV battery system. Personally I have added the step to "make sure battery switch is on" to my towing check list, and "make sure battery switch is off" to my storage check list.

I installed a battery cutoff switch on my Sundance.

Today, with the battery switch turned to the off position, I plugged the Sundance into my truck and determined that the truck battery, even with no engine running, powers up the 12 volt system in the Sundance.

So you do not need to worry how you wire the battery switch, because as long as the trailer is connected to the truck when towing, the trailer emergency brake system is active.

 

[danemayer]

So you do not need to worry how you wire the battery switch, because as long as the trailer is connected to the truck when towing, the trailer emergency brake system is active.

If your trailer falls off the hitch and separates from the truck, it also separates from the electrical connection to the truck battery. At that point the emergency braking system depends on power from your trailer battery.

As to how you wire the cutoff switch, wire it so you don't need to do anything for the emergency braking to work. Adding a step that you have to remember is just inviting disaster.

 

[evolvingpowercat]

Per Dan's advice, if you want to wire the battery cut-off switch to not cut off the ability to put 12 volts across the electric brakes when the break away switch is activated, don't put your cutoff switch right at the batteries:

- the break away switch is connected from the always hot trailer wiring harness 12 Volt Line to one side of the break away switch and to the always hot 12V lead coming from the 7 way connector, at a junction box where the RV 7 way is connected to the main trailer wiring harness. The other side of the break away switch is connected to the 7 way brake lead and the brake lead in the trailer wiring harness.

- in between that junction box and the AC to DC converter, there will be a junction block where the 12 volt line from the junction box, the 12 volt line from the DC fuse panel and AC/DC converter, and the Positive 12 line from the batteries are joined. On my Heartland Edge Travel Trailer that junction block is right behind the batteries under the trailer mounted on the front most frame rail. Note: I was actually surprised how un-protected and exposed this junction block is on my Edge, but I have not done anything about it yet.

- You can't put your cut off switch right at the battery in either pos or negative lead unless you always have it on when you are towing. You have to put it in the positive wire between the junction block and the DC fuse panel, to be able to leave it off and still have battery able to feed the breakaway switch and electric brakes if need be.

 

[JohnDar]

I put my battery switch on the positive battery lead. Since I can't operate the jacks without it being on, there is little chance that I'll try to pull the rig with it off and not have brakes.