DUAL OPTIMA BATTERIES IN STOCK LOCATION: Installation w/ pics

[Sandstormer]

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Like many others I wanted to run dual batteries for things like aux. lights and a winch (someday), but the location most people use for the second battery is reserved for my onboard air compressor.

I like the Optima batteries, but it looked like there was no way they could fit in there. Of course that sounded like a challenge to me...so after a lot of planning, measuring and fabricating I managed to squeeze 2 Optimas into the stock battery location.

Parts:
Optima 35 red top starting battery
Optima D35 yellow top aux. battery
Custom dual battery tray and hold-downs
8" battery hold-down bolts (2 sets)
2 gauge 19" battery cables (2)
SAE post to stud terminal adapters (4)
Painless Add-on Solenoid kit for MASTER/Minder (part# 40112)
4x4mods.com "Batteries" rocker switch
Misc. nuts, bolts, wire, zip ties, etc.

Install
The first step was finding a way to squeeze 2 batteries in place of the stock one.



I found that there is a slightly smaller size of Optima battery that is only 9"x6.7" and I figured that if I bent the existing rear battery hold-down bracket back slightly they should just fit. I ordered them from Optima Battery Deep Cycle Batteries Yellow Blue Red Top Optimum since they had good prices which included shipping and they are based in Nebraska which is where I'm from originally (Go Huskers!).

The real work for this mod was fabricating a dual battery tray and hold-downs that would bolt to the existing battery ledge. Since the new batteries were shorter I used some 1x2 rectangular steel tube with an angle iron tray welded on top. I added some tabs and holes for the hold-down bolts also.


These got a coat of primer and then some charcoal grey Rust-Oleum since I had it left from my third row seat frame mod.



I've seen folks use the Painless Dual Battery Kit, but from what I could tell all I really needed was the solenoid since I was going to run my own wiring and switch. I contacted them to verify that the solenoid that comes in the Add-on Solenoid kit for MASTER/Minder is the same as the one in the dual battery kit...and costs about half as much so I went for it. I still used the dual battery kit install docs though since they were online

I mounted the solenoid inverted up above the fender using a couple of existing threaded holes that I found which lined up pretty well. This keeps it up away from everything but also keeps the battery cables a little better protected below it.



I drilled some holes and bolted the tray to the battery ledge.


Time to throw in the new batteries, it's a tight fit but it they do go in. I used a bolt cutter and bench grinder to trim the hold-down bolts to size a bit.



I'm using the red top starting battery to replace the oem battery so all existing connections were retained except that I relocated the ground connection up to the front and modified the negative cable clamp to fit on a post adapter. The yellow top deep cycle battery will run all my aux. lights, winch (tbd), aux. fuse block, and serves as a starting backup.

The solenoid gets wired to the positive terminal of each battery and a new switch in the console. I reused the old ground connection point for the negative cable off the aux. battery.




The switch controls the solenoid and allows the aux. battery to be brought into or out of the charging loop. For testing, I simulated a dead battery by taking the negative cable off the main battery. Of course nothing happens when the keys go in and it won't start...hit the switch to bring in the aux. battery, dash lights up and it starts like a champ.