HOW TO: Battery master cutoff switch under the rear dinette seat

[John E Davies]

This shows the installation of a Blue Sea 6005 mini battery switch with removable key, it fits neatly into a piece of 3" x 4" aluminum angle, 6061-T6. It can be mounted in a variety of ways, using 5 mm screws and self locking nuts. This mod requires metal working tools and skill, and the ability to fabricate good quality cables. As always, measure twice, cut once, and disconnect the batteries before starting! I chose method C. If you plan to use D, you can purchase a new round label to apply, since the existing one will be covered.

I bought a 12” scrap, leave it LONG until the big hole is cut! Brace that end against the drill press post so it cannot spin and take off your fingers!

Bond a HDPE mounting block to the inside cabinet wall, I like JB Weld. Let it cure overnight. I used a 1" thick piece, thinner would be OK but not as sturdy.

Mount the angle bracket with stainless sheet metal screws, the center hole is not used (that was used as a center for drilling the four outer ones, and also to hold a fixture to clamp it in place).

The switch should be mounted upside down, so the label is easily readable when you put your head down in the hole.

All four screw holes are located so that they are accessible with the switch in place:

Access is reasonably good, there is plenty of room to reach around and get a box end wrench on each one, from below.

Remove the battery Positive cable (this one is 4/0 gauge because there is a 2000 watt inverter installed) and relocate it to the INPUT of the master switch (shorten if necessary and install a new 5/16" terminal end.)

Fabricate a short jumper cable to go from the OUTPUT terminal of the switch and back to the big fuse block that the old cable attached to. Add a red cable boot on that one, the connection is more exposed than the inner one. Add split loom and secure with cable ties.

FYI, I reworked my positive cable by adding a terminal feed through post, so mine comes in from closer to the side of the trailer. A standard installation will have it come down from the existing plastic grommet up high in the back of the box.

Fabricate a placard and mount it upside down near the switch. The red key is removable when in the OFF position, for security. It cannot be removed in the ON position. I do not plan to remove it. If you do, please buy a second key and put it in your spares kit!

Here it is flipped over so you don't have to stand on your head:

John Davies

Spokane WA

[NCeagle]

Excellent craftsmanship as always JD!  I really like the location you chose as compared to OTT - they are putting the master cutoff under the street side bed. 

I have never personally used the master cutoff (I'm sure I will someday).  Do you plan on putting a cutoff between your charger and the batteries as well?  OTT also puts that cutoff switch under the street side bed and I used the cutoff at least 2-3 times a week.  I was seriously considering moving that cutoff to somewhere more accessible until I figured out how to turn the charger off with software.  If I'm ever forced to move that switch, I'd pick under the dinette as well.

[John E Davies]

1 hour ago, NCeagle said:

Do you plan on putting a cutoff between your charger and the batteries as well?  OTT also puts that cutoff switch under the street side bed and I used the cutoff at least 2-3 times a week.

I think that under a bed is a truly horrible location for something you routinely access, unless you travel solo and that bed is not in use, or if it doesn’t have sheets and blankets on it. You could maybe relocate yours to a spot poking through the inner wall near the inverter, if there is room. This mini switch with key would not be very intrusive, but you would need to mount it very high under the mattress overhang so it would not get kicked. It would still be easy to access there.

I picked the location up front for the main switch to keep the cable length as short as possible, I do not like long unprotected cables running all over! OTH I installed individual terminal fuses which could also be added to a standard system.

I have three chargers, the Progressive Dynamics shore power one has no switch, it gets controlled by its circuit breaker under the front table. The solar and Redarc (DC to DC) chargers each have an output circuit breaker like the main DC one Oliver installs, that can be opened (turned off) by pushing the red button. They are under the rear street side bed. When towing the PD breaker is off normally, even if I plug into power. The others should be adequate for my needs, but I haven’t yet tested them in challenging conditions. I normally don’t fuss with them on the move, the Redarc one does get turned off when stored because it has a small parasitic loss.

John Davies

Spokane WA