Here's some of my original mods. I don't know if I posted these here or not.

My duel battery set up was one of the first things I did. It's simlier to the set up in my truck, but a little simplier. Two batteries, one factory 80-100 amp alternator.

The batteries are connected via a solenoid which I can control with a switch that turns it on/off/or on when the ignition is turn on. In most cases, I let the ignition switch the solenoid on and connect the batteries, so that they automatic disconnect when I shut the motor off. That way they can't discharge each other.

Just like my truck, the red battery powers all stock systems. The yellow top powers all auxiliery systems, including radios, gps, computer, off road lights, winch, etc.

I have heater hose covering the main battery wire for the extra, extra protection and a 200amp fuse at the red top end.

For those that don't know, the earlier FJ80s came with the battery mounted on the passenger side, while later models, like came with mounted on the driver's side. Well, once you relocate a few things like the wiper washer bottle, you can bolt up an early factory battery housing for a nearly factory looking duel battery set up.