# Battery Kill Switch



## thatscguy

Interested in putting in a battery cut off switch.. Any tips / tricks? Also exactly what gauge wire and connectors do I need for something like this?


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## Nathan

Many do this by breaking the ground. Use the same gauge wire that you currently have for the ground and simply add a switch between the battery and trailer's frame.


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## CamperAndy

Nathan said:


> Many do this by breaking the ground. Use the same gauge wire that you currently have for the ground and simply add a switch between the battery and trailer's frame.


X2 on the above but the wire size could use an upgrade depending on what the dealer installed. Make sure it is a minimum of 8 awg.


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## BoaterDan

For clarification to those that come across this, "minimum of 8 AWG" means 8 or lower. The numbers work backwards, the smaller the number the thicker the wire.

There are various kinds of automotive kill switches that would work. The only trick is finding a good place to mount them.


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## CamperAndy

BoaterDan - Thanks, it is always better to have more information.


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## Nathan

Chasn said:


> This is what I used (clicky thing). I mounted it on the frame directly under the front of the trailer, up and out of site. Keys are placed in the cargo bay, also, out of site. Works great for us and doesn't let the battery drain during storage periods. BOL
> 
> Ken


That's acutally exactly what is in my SOB 5'er (factory installed). It's easy and works well.

However, if you do switch the negative line, make sure it is on to tow as it will disable your breakaway brakes as well.








On the factory installed units they interrupt the positive feed to the converter, leaving the brakes working even if you leave it off.


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## Chasn'Racin

This is what I used (clicky thing). I mounted it on the frame directly under the front of the trailer, up and out of site. Keys are placed in the cargo bay, also, out of site. Works great for us and doesn't let the battery drain during storage periods. As was stated...just ran the ground wire through the switch. BOL

Ken


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## livetofish

> That's acutally exactly what is in my SOB 5'er (factory installed). It's easy and works well.
> 
> However, if you do switch the negative line, make sure it is on to tow as it will disable your breakaway brakes as well.
> 
> 
> 
> 
> 
> 
> 
> 
> On the factory installed units they interrupt the positive feed to the converter, leaving the brakes working even if you leave it off.


Exactly the reason I put on positive terminal since I often forget until I am in the campground.


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## Oregon_Camper

BoaterDan said:


> For clarification to those that come across this, "minimum of 8 AWG" means 8 or lower. The numbers work backwards, the smaller the number the thicker the wire.
> 
> There are various kinds of automotive kill switches that would work. The only trick is finding a good place to mount them.


Mine is mounted on top of the battery and takes up no additional space.


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## Rob_G

Oregon_Camper said:


> Mine is mounted on top of the battery and takes up no additional space.


I use the same thing and it works just fine with no issues.


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## CamperAndy

livetofish said:


> That's acutally exactly what is in my SOB 5'er (factory installed). It's easy and works well.
> 
> However, if you do switch the negative line, make sure it is on to tow as it will disable your breakaway brakes as well.
> 
> 
> 
> 
> 
> 
> 
> 
> On the factory installed units they interrupt the positive feed to the converter, leaving the brakes working even if you leave it off.
> 
> 
> 
> Exactly the reason I put on positive terminal since I often forget until I am in the campground.
Click to expand...

Unless ALL circuits are broken then the isolation switch serves little purpose. The pre trip walk around should include resetting the switch to the normal use position.


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## GSJ

I put in a marine battery switch on the tongue so I can see with a quick glance if the power is on or off. wires are hiden nicely. I tried to put a pic on...but I couldn't. I also just set up the duel 6V battery system, haven't hooked them up yet...stupid snow


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## Fanatical1

Chasn said:


> This is what I used (clicky thing). I mounted it on the frame directly under the front of the trailer, up and out of site. Keys are placed in the cargo bay, also, out of site. Works great for us and doesn't let the battery drain during storage periods. As was stated...just ran the ground wire through the switch. BOL
> 
> Ken


Harbor Freight carries this same cut off switch. I think I paid $4.00 for it from them.

Mark


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## Cabana Dave

Fanatical1 said:


> This is what I used (clicky thing). I mounted it on the frame directly under the front of the trailer, up and out of site. Keys are placed in the cargo bay, also, out of site. Works great for us and doesn't let the battery drain during storage periods. As was stated...just ran the ground wire through the switch. BOL
> 
> Ken


Harbor Fright carries this same cut off switch. I think I paid $4.00 for it from them.

Mark
[/quote]

Great deal Mark. I just received mine from HF yesterday, and will install it when the snow melts. The switch instructions states; it is to be installed in a dry location. Does anyone know if the battery/propane area is 'dry enough' for this switch?

Thanks,
Dave


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## Fanatical1

Cabana Dave said:


> This is what I used (clicky thing). I mounted it on the frame directly under the front of the trailer, up and out of site. Keys are placed in the cargo bay, also, out of site. Works great for us and doesn't let the battery drain during storage periods. As was stated...just ran the ground wire through the switch. BOL
> 
> Ken


Harbor Fright carries this same cut off switch. I think I paid $4.00 for it from them.

Mark
[/quote]

Great deal Mark. I just received mine from HF yesterday, and will install it when the snow melts. The switch instructions states; it is to be installed in a dry location. Does anyone know if the battery/propane area is 'dry enough' for this switch?

Thanks,
Dave
[/quote]

Dave,

I have not mounted mine yet, still waiting for the snow to melt. I plan on mounting the switch in a 1 x 4 piece of treated lumber under
the propane cover with the key switch facing down. The board will be screwed to 2 existing metal braces under the cover.

My thoughts are that I can reach under the edge of the propane cover and fit the key into the switch without having to remove
the cover each time, which is a bit of a pain. Should stay reasonably dry with the switch under the cover and facing down. 
Anyway, that's the plan for now....

Mark


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## Moosegut

Because winter camping has always been our thing, I mounted my battery switch inside the TT. That way, I could switch to a fresh battery in the middle of the night without having to wake DW up and send her outside in the snow and sleet to switch batteries.

On really cold nights the furnace runs quite regularly and one battery often does not make it to morning so I need to switch. In the morning I just fire up the generator and charge both batteries back up.


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## BoaterDan

Moosegut said:


> Because winter camping has always been our thing, I mounted my battery switch inside the TT. That way, I could switch to a fresh battery in the middle of the night without having to wake DW up and send her outside in the snow and sleet to switch batteries.
> 
> On really cold nights the furnace runs quite regularly and one battery often does not make it to morning so I need to switch. In the morning I just fire up the generator and charge both batteries back up.


Why wouldn't you just leave the switch on "both" and sleep through the night?


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## Moosegut

BoaterDan said:


> Because winter camping has always been our thing, I mounted my battery switch inside the TT. That way, I could switch to a fresh battery in the middle of the night without having to wake DW up and send her outside in the snow and sleet to switch batteries.
> 
> On really cold nights the furnace runs quite regularly and one battery often does not make it to morning so I need to switch. In the morning I just fire up the generator and charge both batteries back up.


Why wouldn't you just leave the switch on "both" and sleep through the night?
[/quote]

I have different sizes - and I NEVER sleep through the night.


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## cygnus23

CamperAndy said:


> That's acutally exactly what is in my SOB 5'er (factory installed). It's easy and works well.
> 
> However, if you do switch the negative line, make sure it is on to tow as it will disable your breakaway brakes as well.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> On the factory installed units they interrupt the positive feed to the converter, leaving the brakes working even if you leave it off.
> 
> 
> 
> Exactly the reason I put on positive terminal since I often forget until I am in the campground.
Click to expand...

Unless ALL circuits are broken then the isolation switch serves little purpose. The pre trip walk around should include resetting the switch to the normal use position.
[/quote]

I know this is an old thread, but as these things go, I'm looking at adding a cutoff switch for my RV and found this through google, so I thought I'd at least try and get a clarification on this. On my RV the positive side of the battery goes to a junction box on the under the chassis where it splits off power to the breakaway switch. The other line leading from the split which feeds the fuse box / inverter/charger could have the cutoff switch installed, without killing power for the breakaway switch, allowing it to always have power. Per the comment "Unless ALL circuits are broken then the isolation switch serves little purpose.", would the breakaway switch actually draw any power? I would think it is itself a switch that is in the normally open position, or am I simplifying its design too much? I didn't think the breakaway switch had any active electronics, at least not any that were in play without it being "triggered"? Can anyone confirm/refute?

Thanks!


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## RDS

The breakaway switch is normally open but to make it work you will have to put your battery cutoff switch on the positive side and wire breakaway switch directly to battery.

If the cutoff switch were on the ground side the breakaway would not work no matter how it was wired as the electric brakes would have no path to ground....


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## cygnus23

RDS said:


> The breakaway switch is normally open but to make it work you will have to put your battery cutoff switch on the positive side and wire breakaway switch directly to battery.
> 
> If the cutoff switch were on the ground side the breakaway would not work no matter how it was wired as the electric brakes would have no path to ground....


Thanks for the response! I was wondering more about a previous posters claim about needing to switch off everything to not have current draw while stored. I'm assuming 2 things: 1) I would never want to forget to flip the switch and not have power for the brakes in a breakaway situation. and 2) the breakaway switch should not draw any power when inactive, therefore not needing to part of any kill circuit anyhow. I was planning to have the breakaway switch always connected to the battery, whether kill switch is engaged or not. Does this seem like the correct course of action?


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## CamperAndy

The break away switch can be wired to the battery directly and bypass the kill switch as there is no parasitic load from the break away switch.

Just remember if you park your trailer in a public storage place you may still have to deal with someone pulling the cable on the breakaway switch. If you have a kill switch it is best to have it isolate everything and be out of sight, then you just have to remember to turn it back on when you hook up to pull the trailer.


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## mmonti

I used this dual battery switch Blue Sea battery switch. I used stainless nuts and bolts and mounted it under the propane cover, i cut the negative side of the battery. I always turn on the batteries while hooking up the hitch. I never realized the breakaway switch wasn't powered full time I was under the impression it was straight to the battery? I need to take a better look at mine.


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