This is technically part two of a series of articles on upgrading your FJ Cruiser’s electrical system. Part one discusses the addition of a second deep-cycle battery to support additional fuse panels and other accessories. The main idea behind the second battery system is to isolate all the aftermarket accessories as much as possible from the stock wiring. In addition, a deep-cycle battery is much better equipped to deal with low-draw accessories such as a fridge because it will drain much slower than a traditional starting battery. Overall, if you plan on running more than a few minor electrical accessories, a secondary battery system is highly recommended. However, even if you are sticking with the factory battery setup, the general concepts of this article should still apply.

In my case, since I already have an auxiliary battery in place, I’ll be integrating this new fuse panel into the secondary system. Preparations and requirements for adding a fuse panel may vary from application to application. A lot of the details depend on how much amperage you plan to draw. Any large-draw accessories, such as off-road lights, will end up using a separate system that ties more directly to the battery using a series of relays and switches. The intent behind the fuse panel is to support a large assortment of low-power accessories like music and movie players, cellular phones, and portable GPS devices. Continue Reading →