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Battery Cut-Off Switch Installation

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How I Installed a Battery Cut-Off Switch:

After much delay becuse I couldn't figure it out, I finally installed a battery cut-off switch on our Ollie hull 217, and it turned out easy to do.  We store the trailer at a remote covered location.  I didn't like to keeping the batteries on charge for long periods, and I didn't like the seemingly unavoidable small drains take the batteries down over time.  My new switch installation cures both these problems.

I know other owners have installed similar switches, but still wanted to share my method.  The installation will be familiar to anyone with boating experience.

I wanted the switch inside for convenience, and because I had installed safety bolts on the slides on each side of the battery rack.  The rack is really secure, but removing these bolts takes a bit of time.  Fortunately on my Ollie both of the two hot (+) wires installed by the factory and and coming off the batteries both go through the aft compartment wall and into the space underneath the streetside bunk.  That greatly simplified my switch installation. 

The steps were:
1.  Disconnect & remove batteries from rack.  With four batteries there are a lot of short connecting wires.  Take a picture or make a sketch before you disconnect anything so you know battery orientation and what wires go back where.
2.  Install a Blue Seas or similar marine battery switch underneath the streetside bunk.  With a properly sized hole saw and a bit of sanding the body of the switch can be placed into the under-bunk compartment with only the switch face projecting into the living space.
3.  Pull the two factory installed hot (+) supply wires through the aft compartment wall and into the space under the streetside bunk.  Do not disconnect the wires from their connections inside the under-bunk compartment.
4.  Prepare and run a new hot (+) supply wire to run from the batteries to the new switch.  There needs to be enough slack so that the battery rack can be pulled out once the installation is complete.  In my case I used  48" of #6 gauge wire, with a 5/16" and a 3/8" terminal at each end.  Only #6 gauge wire, because most everything in our Ollie is low amp load LED or solid state.  If I had a larger amp draw, perhaps from an inverter, I would have used #2 gauge wire for the new supply run, and used automotive lugs which can handle a higher amp load.  Run the new supply wire through the battery compartment wall and hook up to the input side of the Blue Seas switch.
5.  Continue to leave the old hot (+) wires connected to the factory installed terminals inside the under-bunk compartment.  Prepare new runs for these two wires backwards so they can be hooked up to the load side of the new switch.  Cut the wires to the right length so they can be connected to the new switch without too much excess length.   Install new wire terminals and connect these two wires to the load side of the new switch.  Secure these wires from vibration along their runs with self-stick mounts and cable ties. 
6.  Carefully reinstall  the batteries and rewire.
7.  When desired, turn off the new switch to completely disconnect batteries from the trailer load.  If plugged in, I disconnect shore power before doing so.

Best regards to all,
John Shkor














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Posted (edited)

Nice job, John, and great writeup.  I debated placing my cutoff where it's more easily accessible but my wife vetoed that idea pdq.  I considered actually doing a Blue Sea 360 panel that had cutoffs for both the batteries and solar, manual transfer switch for my charger, and breakers in place of the 12 volt fuse panel, but geez the cost of that was astronomical, not to mention the time to rewire everything.  And again, my wife just doesn't appreciate the aesthetic of visible electronic equipment, even if it's marine grade.



Edited by Overland

Snowball • 256 • 2018 Ford Raptor

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Nice job. I did a temporary cut-off that currently resides in the battery compartment. I used a basic Harbor freight switch that I had laying around and a small plastic junction box fastened to the floor of the battery tray where batteries #3&4 (which I don’t have) go using command strips. 

I plan to upgrade to lithium in the next couple years and will install One like you did.   Again good work and good clear write-up. 

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Fully understand.  The Blue Seas 360 is a nicely engineered panel.  And if you have spent enough time inside the boat cabin during foul weather, electrical panels begins to look good anyway.
Look forward to reading about your 12V lithium ion battery experience.  We have lithium batteries in two electric bikes, and they pack a lot of power in a small package.
Best regards,
John Shkor 



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