This is how I built my FJ Cruiser DIY Dual Battery Setup.
I spent A LOT of time researching on this forum (fjcruiserforums.com) and talking with local ham radio guys and 4×4 enthusiasts.
link to thread https://www.fjcruiserforums.com/forums/stereo-electronics-electrical/145415-diy-dual-battery.html#post2142432
I have looked over several installed dual battery kits on this forum, I knew it could be done cheaper. Not necessarily with cheaper lower grade parts, but for less money. The battery I used may not be an Odyssey or an Optima, but it works and it works very well. I have parallel batteries and that is a huge plus when you are running lots of auxiliary electrical gadgets or lights. I’m pleased with outcome of this mod. I now have a good base point to start with my electrical mods. Over half of the parts I used were made in the USA, the Solenoid, cable, lugs, battery tray, heat shrink, and terminals.
I hope this thread helps others lik myself that wanted dual batteries but wanted to keep it around $150.
-Marine Battery $58
-Group 24 battery tray and hold down $12
-9ft of Red 4ga welding cable $2.75 a foot – $24.75
-3ft of Black 4ga welding cable $2.30 a foot – $6.90
-2 Terminals 2 @ $4.99 installed – $10
-Heat shrink $4
-Lug — Starter type 4ga 5/16″ eye 4 @ $1 — 4$
-2 — 6mm x 8mm and washers $1.50
-12ga black and red wire for solenoid free, I had it lying around
-12v constant duty solenoid $23.35
-40/80 amp fuse block $10 (I don’t really care for this fuse, I may replace it)
-Grand Total about = $161.50
Post time: Mar-14-2018