It seems a lot of folks already have a dual battery setup, but I though I’d show how mine is done. Thanks to Ed Cooke who used to work at 4×4 Connection for assisting in the design.

The primary battery is wired normally to the isolator, but the secondary runs through a circuit breaker to the isolator. An FJ-40 fuse block is in parallel with the secondary connections to provide power for accessories.

You will also have to relocate the coolant overflow tank. There appears to be a mounting bracket for it already on the fender.

Figure 1 is a schematic of the setup. Figure 2,1 shows the fuse block in the ‘Cruiser. Figure 2,2 shows the location of the coolant tank.