Forgive me, I am confused. I have a TT with two 12V batteries hooked up in parallel. I store my TT at a storage facility and want to help protect my new batteries. I purchased a battery disconnect switch and am confused on how to hook it up. I'll mount the switch to one of the battery boxes and the switch has two posts. Specifically how do I connect it. Do I need another jumper cable from the ground of the second battery to the switch? What goes on the second post on the switch? The trailer ground? Sorry not good at this kind of stuff. Thanks for you help.

Take the switch back, get your money back. Then go buy a 50A fuse holder and fuse. It will go between the battery plus(+) and where the cable goes into the trailer. When you want to store, simply pull the fuse.

If you disconnect either cable from the battery, no current can flow through the system, which is the goal of a cutoff switch. If you have two batteries in parallel, the switch goes from both positive battery posts to the positive cable going to the TT, or from both negative posts to the negative (ground) for the TT. Once installed between the battery(s) and TT, it simply opens the circuit so no electricity can flow. You will most likely need at least one additional cable to make that happen. Hope this was helpful.

Wire it on the negative line between the second battery and the trailer.

1. you will have a + and a - cable between the batteries to parallel them.2. wire the Trailer + to battery 1 +3. wire the Trailer - to one side of the switch4. You need a new wire to connect the other side of the switch to battery 2 -IMO the switch is more convenient than pulling the fuse, also the switch should be on the negative side not positive like the fuse would be.

downtheroad wrote:Wire it on the negative line between the second battery and the trailer.hedge wrote: also the switch should be on the negative side not positive like the fuse would be.Don't do this. It will disable the breakaway brake on the trailer. Connect it to the positive wire. That way the breakaway trailer brake will still be functional even if you forget to turn the battery back on before towing.

Battery disconnect switch - confused | Good Sam Community

Burnt_Marshmall
Explorer
Apr 14, 2017
downtheroad wrote:
Wire it on the negative line between the second battery and the trailer.

That's what I do. Current comes off the negative side on a DC battery.
352
Explorer
Apr 13, 2017
Put in a ( Perko ) switch. Look it up
Lwiddis
Explorer II
Apr 13, 2017
"IMO the switch is more convenient than pulling the fuse"

Me too, Hedge.
samsontdog
Explorer
Apr 13, 2017
coolbreeze01 wrote:
Trailers usually come with a battery disconnect switch.

Very few that I have bought came with one.
Bobbo
Explorer II
Apr 13, 2017
hedge wrote:
Bobbo wrote:
hedge wrote:
What difference would it make (+ or -)? it would disconnect the breakaway either way as far as I can surmise.

In either way the breakaway could be wired to bypass it.

I've only owned two trailers but both of them only had a single point battery connections so a disconnect on either side would have disabled the breakaway.

The breakaway switch should be wired prior to the disconnect. That way the breakaway switch ALWAYS has power. It has NO drain on the battery as long as the pin isn't pulled, so there is no reason it should be after the disconnect.

I guess I've just never seen a trailer wired that way.. but I haven't owned a trailer in a few years.

It's still just convention, a bypass could be wired on the negative side as well.

While the negative could be bypassed, it would be difficult since the brakes are grounded through the frame.
hedge
Explorer
Apr 13, 2017
Bobbo wrote:
hedge wrote:
What difference would it make (+ or -)? it would disconnect the breakaway either way as far as I can surmise.

In either way the breakaway could be wired to bypass it.

I've only owned two trailers but both of them only had a single point battery connections so a disconnect on either side would have disabled the breakaway.

The breakaway switch should be wired prior to the disconnect. That way the breakaway switch ALWAYS has power. It has NO drain on the battery as long as the pin isn't pulled, so there is no reason it should be after the disconnect.

I guess I've just never seen a trailer wired that way.. but I haven't owned a trailer in a few years.

It's still just convention, a bypass could be wired on the negative side as well.
enblethen
Nomad
Apr 13, 2017
The switch has two posts.
One goes to the batteries. It can go to the negative or positive. Many feel negative is better. You would run from batteries, one wire each to one post.
Other post goes to the rig's power distribution panel.
There should be a fuse or circuit breaker at the battery to protect the wiring between batteries and the power distribution panel. It can be either side of the switch.
The break away switch must stay active even when switch is in the off position.
Bobbo
Explorer II
Apr 13, 2017
hedge wrote:
What difference would it make (+ or -)? it would disconnect the breakaway either way as far as I can surmise.

In either way the breakaway could be wired to bypass it.

I've only owned two trailers but both of them only had a single point battery connections so a disconnect on either side would have disabled the breakaway.

The breakaway switch should be wired prior to the disconnect. That way the breakaway switch ALWAYS has power. It has NO drain on the battery as long as the pin isn't pulled, so there is no reason it should be after the disconnect.
coolbreeze01
Explorer
Apr 13, 2017
Trailers usually come with a battery disconnect switch.
hedge
Explorer
Apr 13, 2017
What difference would it make (+ or -)? it would disconnect the breakaway either way as far as I can surmise.

In either way the breakaway could be wired to bypass it.

I've only owned two trailers but both of them only had a single point battery connections so a disconnect on either side would have disabled the breakaway.