Battery disconnect switch

Discussion in 'Power - Site Power/Batteries/Generators/Solar' started by jm88, Apr 14, 2017.

  1. jm88

    jm88 Member

    Feb 12, 2017
    I have the configuration below connecting to my battery. Looks like the blue wire goes to the breakaway switch. If I connect a battery disconnect switch, would I want to put it between the battery and that breaker, or between the breaker and the converter? And I am thinking I should probably hook that blue wire direct to the battery rather than turning the switch on while I am towing it. Does that sound right?

  2. Customer

    Customer Well-Known Member

    Jun 5, 2014
    For a trailer the disconnect goes in the positive line and the breakaway line is attached prior to the disconnect.

    Before or after the breaker doesn't matter but unless you relocate the breakaway line it should be after with the way yours is currently connected.
  3. tombiasi

    tombiasi Well-Known Member

    Breakaway power should be directly to the battery and un-fused and un-switched.
  4. tenttrailer

    tenttrailer Art & Joyce - Columbus, O

    Jul 18, 2013
    Thornville, OH
    +2 to both the above responses.
  5. roybraddy

    roybraddy Active Member

    Mar 23, 2016
    King George, Virginia
    On my Starcraft 14R/T setup i have a some wires direct connected to one of my multiple batteries in my battery bank which is mounted on the tongue of the trailer... The trailer roof raise DC motor and the power connections for the breakaway switch to provide a full 12V to the trailer brakes if activated are two that come to mind... These are always providing 12V regardless of my Battery switch operation... I have a third line going to the 12V connection of the truck 7-way connector for trickle charging my one battery in the battery bank when the truck is running. This will trickle charge all batteries depending how the Blue Sea switches are selected.

    My Battery disconnect is on the positive side of the battery wiring and is shown here below. I use those BLUE SEA four position manual rotary switches where the positions are OFF-BAT1-BOTH-BAT2 then OFF again. I have he same arrange in each of my two battery zones. This gives me control of using just ONE-ALL-NONE of my batteries by which position the Bluw Sea switches are in... I can switch out one whole bank her and recharge them or run some of my two way radio circuits without disturbing the trailer operations...

    Roy's image

    These GP24 12V batteries are all but used up now and I am working on changing to two roups of two GC2 6V T105's for this upcoming season... Will look something like this... This will only be using one of those BLUE SEA battery switches. I also have a second AIMS PSW 600WATT Power Inverter being used now in addition to the 1500WATT unit which very seldom get used...
    Roy's image

    My setup using Battery Disconnect switches...

    Roy Ken
    Last edited: Apr 17, 2017
  6. nizon

    nizon Member

    Sep 11, 2015
    Yikes, never connect anything unfused, especially your breakaway circuit.
    Your brake power wires are exposed to some nasty conditions below the trailer (road debris, water, rodents, etc). It's the most likely circuit to see a failure.
    Wouldn't want your trailer to go up in flames because a brake wire shorted.

    Remember to check your breakaway circuit before towing.
  7. tombiasi

    tombiasi Well-Known Member

    It is not supposed to be fused.
  8. nizon

    nizon Member

    Sep 11, 2015
    Well I've seen a few arguments that it shouldn't be fused.
    However if there's a short in your brake wiring it's going to shunt all the current from the battery and your brakes will fail anyway. So it doesn't really hurt to have a fuse.
  9. SteveP

    SteveP Member

    May 21, 2015
    If brake wiring is damaged aft of the break away switch there will be no draw on the battery unless the switch is engaged. I've had a shorted switch, which resulted in a 7 amp draw from the battery. So the only "danger" of short is the wire from the battery to the switch.

    The breakaway switch must not be fused with the house fuse. The house fuse is likely to fail for other reasons and the house fuse is too heavy for the wire to the the switch anyway. If you want to fuse it with no greater than a separate 15 amp fuse I wouldn't argue it. But I don't consider it necessary.
  10. tombiasi

    tombiasi Well-Known Member

    It's not a matter of necessary. It's code to have it direct wired.
    You may be surprised to find out that the large 3 phase motors that power the fire pumps that push water up the high rise buildings is direct wired with no circuit breakers or fuses. It's a function critical device.
  11. tfischer

    tfischer Well-Known Member

    Fuses can blow quickly. Lets say your brake wire had a nick in it and it blew against the frame just right for a split second. Fuse goes "poof", now you don't have emergency brakes.

    Without the fuse in that case, you might have a little spark, but you still have brakes.
  12. tenttrailer

    tenttrailer Art & Joyce - Columbus, O

    Jul 18, 2013
    Thornville, OH
    I have had trailers that the manufactures have and have not fused the breakaway switch. I think it depends on your school of thoughts. I like the idea of no fuse.
  13. Snow

    Snow Well-Known Member

    Jul 19, 2007
    Brake away switch on my TT is wired to the battery side of the circuit breaker, so still works as if it is directly wired to the battery.. This is unaltered factory wiring..
  14. nineoaks2004

    nineoaks2004 Every meal is a picnic and every Day is a holiday

    Oct 15, 2006
    Graceville, Florida
    Blue should be connected to the Battery and is never fused it is the break away switch (or should be anyway) the battery disconnect should be hooked to the positive battery post then to one side of the circuit breaker and from circuit breaker to the camper wiring.

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