Ryan McKee


When we left off, we had been discussing the specific parts required for a good, safe, dual-battery installation in your vehicle. Whether you’re debating a second battery simply for peace of mind, or because you know you’re asking too much from your factory installed starting battery, a properly assembled dual-battery system can be a great addition to any set up. Once the fundamental parts have been gathered, it’s time to get everything wired up, and since we’re dealing with a fair amount of voltage, it’s crucial to ensure things are done correctly.

First we’ll begin the process of wiring between the starting battery and house battery by utilizing one of the two high-amperage fuses. The best placement for the first fuse is as close to the starting battery as possible (#1) so that in the event of a surge, the fuse blows before voltage can travel too far, cutting down the risk of an electrical fire drastically. Once the first fuse is inline, you’ll run another length of appropriately gauged cable from the newly placed fuse to your battery solenoid (#2). Depending on the solenoid you chose to buy, you’ll either need to utilize the ground wire included, or add a ground wire on your own. From the solenoid you’ll be connecting to the second of the two fuses (#3), and then on to the positive post of the house battery (#4). Following (#6) the battery ground wire run, you can connect straight from the house battery negative post to the same post on the starting battery.


At this point, you’ve got free reign of the rest of your set-up. You can either wire up a fuse block like one that Blue Sea Systems offers, or can wire your lights, switches, and relays up directly to the battery post. You’ve got the correctly fused equipment and safely set-up to have a well functioning dual-battery system in your vehicle. While the benefits may not be immediately apparent, taking the strain and extra power draw away from your starting battery will work in your favor in the long run. While most deep-cycle batteries aren’t designed to start a vehicle, you can even utilize the house battery to jump the starting battery in the event that it dies unexpectedly.

As with all things we encourage attention to detail and appropriate safety precautions when working with vehicular electrical systems. Without being a huge investment, the freedom and eased concern a second battery allows for make it a well worth it modification for anyone with serious lighting, radio, and other electronic upgrades.