Battery disconnect - switch or fuse?

OP here. Thanks for all the help! I've ordered a master cutoff switch and 20" 6 gauge battery cable. Plan to mount it on the outside of the battery box, under the box handle. I'll pull the 10A fuse and see if the slide works....did not consider that the slide might have its own fuse.

The 10A fuse could for the slide out if the trailer has one.
Take your pick negative side or positive side for the switch. I would be inclined to use an inline circuit breaker on the side with a single wire.

KD4UPL wrote:
The 10 amp fuse you pulled is likely for the break away brakes. Put it back.
A negative disconnect will probably also disable the break away brakes so you can't pull the trailer on a road with it turned off.
I'd just use a circuit breaker in the positive main wire.

Breakaway brakes are not supposed to be fused.

wa8yxm wrote:
I would go with a switch and the Negative cable is a good spot or it.
I've seen a lot of argument on negative or positive. but I favor Negative.

On many RV's there are multiple POSITIVE wires is one reason

Another is if you are removing the battery and start with the POSITIVE lead.. if the swich is off and the wrench slips. No harm done

But if the switch is in the positive you can end up with a nasty burn and a melted wrench and worse.

Multiple positive wires can be combined.

Always remove the negative cable from the battery first. That way, if the wrench slips when removing the negative cable, no problem. If the wrench slips when removing the positive cable, no problem. In other words, the wrench slipping is never a problem.

If the switch is on the positive, you can’t get a nasty burn and a melted wrench and worse because you took the negative clamp off first.

If you look up battery switches, the instructions call for the switch to be installed on the positive side.

Not hard to tie multiple Positive side wires together, so that's not really a reason.

If the wrench slips and connects both battery terminals, you still get excitement regardless of which side is switched.

On the other hand, if you are leaning against something metal and touch the negative battery terminal (with a negative side switch turned off), you just completed the circuit (frame and metal parts are typically tied into the grounding system. Probably won't die with 12v but not fun.

Generally, the brakes get a dedicated unfused line but for winter storage, I still prefer to disconnect (always do a brake test when pulling out, so if you forgot to reconnect, it will immediately be obvious).

I would go with a switch and the Negative cable is a good spot or it.
I've seen a lot of argument on negative or positive. but I favor Negative.

On many RV's there are multiple POSITIVE wires is one reason

Another is if you are removing the battery and start with the POSITIVE lead.. if the swich is off and the wrench slips. No harm done

But if the switch is in the positive you can end up with a nasty burn and a melted wrench and worse.

I use a battery switch like bob213 linked to but mine is on the positive cable. I never shut this switch off unless I'm working on the 12-volt battery system.

The 10 amp fuse you pulled is likely for the break away brakes. Put it back.
A negative disconnect will probably also disable the break away brakes so you can't pull the trailer on a road with it turned off.
I'd just use a circuit breaker in the positive main wire.

bob213 wrote:
This is what I use and I have it on the negative cable without problems. Many will tell you this is wrong and it might be but it has worked on two trailers for 14 years.
Battery switch

It's only wrong if it also disconnects the breakaway brakes.

Mine came with one. It's under the propane tanks. You have to reach under and then turn the red 'key'. I'm not sure how it's wired, but it's probably on the NEG cable I would think since it's an RV?

Mitch

I use a 12 volt circuit breaker, works great.