Dual battery disconnect question

[campinAZ]

I purchased a BEP Marine 701 Contour battery switch. I'm thinking I can connect the switch after where the two negative battery cables come together (handle both batteries). Do you agree or is there something I'm not considering.
Thank you in advance.

[wwt]

Sounds right to me. If you see two black wires going into one and you cut the single wire there's no other way for the power to travel.

[campinAZ]

Thanks! It went as planned and worked.

[TakerEasy]

I understand on many rv sites people like disconnecting the negative side however be aware that most travel trailers use the battery for the emergency brake system. Unless you remember to turn on the disconnect switch each time before you travel, your emergency brakes will not work. There is not a good way to isolate the house portion from the brake portion when disconnecting the negative side because there are too many common grounds you have to consider.

Installing the disconnect between the house's 12 volt positive and the batteries and leaving the brake switch connected directly will allow the brakes to always function. You can leave the electric jack as direct or thru the switch depending on what your preference is.

Richard

[Mustang65]

Originally Posted by TakerEasy

I understand on many rv sites people like disconnecting the negative side however be aware that most travel trailers use the battery for the emergency brake system. Unless you remember to turn on the disconnect switch each time before you travel, your emergency brakes will not work. There is not a good way to isolate the house portion from the brake portion when disconnecting the negative side because there are too many common grounds you have to consider.

Installing the disconnect between the house's 12 volt positive and the batteries and leaving the brake switch connected directly will allow the brakes to always function. You can leave the electric jack as direct or thru the switch depending on what your preference is.

Richard

Richard,
Good point on the brakes, and it is possible to forget to turn on the disconnect switch when traveling. I have yet to do that, but I have solar and run my fridge off the inverter (not gas) as we travel, so I guess that is why never forget.

As for there are to many common grounds connected to consider, there is only one ground connection (on a properly wired TT circuit), and when the ground is opened at the switch, the battery is no longer part of the TT circuit. It is an open circuit. Just like pulling the battery out of a flash light. No connection.

Don

[TakerEasy]

I guess it depends on which brand because I've torn several travel trailers down to the frame for complete floor replacement and guess what, they use the frame for ground on many items such as lighting, secondary safety grounds, clearance and tail lights, brakes.

So what I'm saying is if you disconnect the ground to the house & frame, you are also disconnecting it from the brakes, but if you disconnect the positive from the house, you isolate the house from the battery but still have brakes.

My point about too many common grounds was for the folks that I've seen state that you can keep the brakes grounded and remove the ground from the house which will be pretty difficult because most brakes are grounded to the frame, not all, but most. Again, many things share the frame ground.

Richard

Originally Posted by Mustang65

Richard,
Good point on the brakes, and it is possible to forget to turn on the disconnect switch when traveling. I have yet to do that, but I have solar and run my fridge off the inverter (not gas) as we travel, so I guess that is why never forget.

As for there are to many common grounds connected to consider, there is only one ground connection (on a properly wired TT circuit), and when the ground is opened at the switch, the battery is no longer part of the TT circuit. It is an open circuit. Just like pulling the battery out of a flash light. No connection.

Don

[GrumpyDad]

I put a disconnect between my two batteries once, and had a few people tell me it was stupid to do it that way. I didn't understand why until I went to sell the trailer and sold it with a singe 12V battery instead of the 2x6V setup. Had to rewire the disconnect.

Anyway, that's mostly off topic, but thought someone could learn from my mistake.

[Mustang65]

Originally Posted by campinAZ

I purchased a BEP Marine 701 Contour battery switch. I'm thinking I can connect the switch after where the two negative battery cables come together (handle both batteries). Do you agree or is there something I'm not considering.
Thank you in advance.

Do you have your batteries wired as in the picture below?
We are talking about (2) 12Volt batteries, correct?

IF so the cutoff switch can go on either Pos or Neg side.

Don


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