Installed Battery Cut Off

[Ronyx]

Hi Everyone,

I wanted to share my battery cut off project I just completed. In the past, when storing my FC19 I would disconnect the negative battery leads. This worked but was inconvenient. Since buying our FC19 a couple years ago, I've pondered how to install a good quality switch, while at the same time cleaning up the wiring. I mulled this over on an off for some time and read the many posts relating to battery wiring, battery boxes, and cut off switches.

The supplies I gathered included:

• Ring Terminals, 2-6 AWG in 5/16 and 3/8 ring sizes
• 2 AWG Extreme Battery Cable
• Blue Sea M-Series 4 possition switch
• Heat shrink tubing - heavy wall, adheasive lined
• Terminal boots
• Hydraulic terminal crimper
• Cable Cutter
• Stainless steel allen key bolts and nylock nuts

I had several goals with this project

1. Simple cut off switch operation
2. Clean, attractive installation
3. Durability
4. Safe and reliable

I sourced these materials from Battery Cables USA, Del City, Ebay, KMS Tools and The Bolt Supply House.

Wanting good quality terminal crimps I used a relatively inexpensive hydraulic crimper from eBay. The crimp was followed up with heat shrink and a terminal boot.

[Ronyx]

Initially I wanted to install the switch on the awning side of the batter box. However, given limitations imposed by the battery box size, positive battery cable length and positioning of the terminal connections on the switch I settled for an in-battery box installation.

This was made possible by pushing the batteries to the front of the battery box under the lip. As you will note in the photo this configuration presented a challenge with the installation/removal of the street side battery.

Fortunately, the battery hold-down rod is threaded into the bottom of the battery box and can be removed to allow the battery to slide to the awning side and then backward for removal. Anti-seize compound was put on the rod where it threads into the battery box to ensure it remains removable.

Figuring out how to mount the switch in a manner that I was happy with took some time. I considered a number of options but none that I found satisfactory. That is until I came upon this perfect little piece of sheet metal that was part of the old Paralax converter, which, I had recently replaced with a PD unit.

[cptdzl]

Very nice work. Well thought out and executed.


Can you explain the ?store?switch? inside the door to me (hopefully soon to be airstream owner) I've seen threads here stating that the battery's still go dead over time even when using that switch.

[Ronyx]

It should be mentioned that the serial battery cable and the positive battery cable to the switch were both assembled using 2 AWG Extreme Battery Cable from Battery Cables USA. This cable is super flexible and has a terrific two-layer jacket.

Next came:
priming and painting the switch bracket
drilling mounting holes for the bracket in the battery box
test fitting cables and switch

The house batteries, external solar charge port and tongue jack are connected to position 1. The inverter is connected to position 2.

I used stainless steel bolts washers and nylock nuts for mounting the switch to the bracket and also for mounting the bracket to the battery box.

The switch knob sweeps under the lip of the battery box and works alright. What I should have done was drilled the switch hole in the bracket a little farther out. Regardless, the switch works really well, and I’m pleased with the finished result.

If any of you with more skill, knowledge and experience see anything that could or should be done differently, please let me know.

[Ronyx]

Originally Posted by cptdzl

Very nice work. Well thought out and executed.


Can you explain the ?store?switch? inside the door to me (hopefully soon to be airstream owner) I've seen threads here stating that the battery's still go dead over time even when using that switch.

The Store Switch disconnects the batteries from the 12 volt distribution system ... sort of ... there are a number of systems that are not disconnected including the inverter, subwoofer and propane detector. The result is that even in the store position there are drains on the battery. This is why I wanted a way to completely disconnect the battery when the trailer is being stored for any period of time.

[AirstreamCSH]

Excellent work and Thank You for posting.
The next person looking to do this will be very glad you did.

[open01]

I can understand disconnecting battery for some maintenance, but have not found it necessary for outside storage. We installed a small by today's standards solar panel ~50W over 20 years ago, and unfortunately the trailer has not moved as often as it should due to other commitments. Even though it has not moved I have had only two batteries in that time first was lead acid, current is agm. The current battery is about 4 years old, and it has never drained, Our trailer is a 1972 31 ft, so does not have modern electronics beyond the univolt being changed for an inverter, and simple charge controller for the solar panel. The solar panel seems to maintain the battery perfectly, I always have lights when I go out to the trailer and even use the furnace for short periods when necessary, so for me I wonder how often I would need to disconnect the battery to make a cut-off system necessary. Nice work on the implementation though.

[Ronyx]

I guess that's what we get when more electronic/electrical features are added to a trailer. I found that with the factory battery disconnect switch set to store that the batteries would be dead in about 4 weeks. Hence the desire to completely disconnect the battery.