Jeep JK Dual-Battery System - 4 Wheel Drive & Sport Utility Magazine

Jeep JK Dual-Battery System Christian Lee Contributor Photographers: Gary Goetz

When the crew at Genesis Offroad in Olive Branch, Mississippi, wanted to install a dual-battery system in their project JK, they did what any of us would and searched the Internet high and low for a kit that would meet their needs. When all they found were basic trays that didn’t include any wiring or relays or isolators, let alone instructions on how to assemble a system, they got smart and decided to make their own. What resulted is the most complete and easiest to install dual-battery system for the JK Wrangler.

Launched at Jeep Beach 2013 in Daytona, Florida, the dual-battery system is now offered for 2007-to-2013 Jeep JKs (including those with HEMI engine swaps). The new heavy-duty dual-battery box replaces the stock bulky plastic battery tray and has an integrated relay box holder that makes it quick and simple to re-install the relay box securely. Extra gussets are built into the bottom mounting bracket to stiffen the entire box, making this one of the toughest battery trays available.

The top cover plate has quite a few innovative features. All of the wiring has already been completed, and the smart isolator comes pre-installed. Welded gussets on top have holes with rubber grommets to route the wires directly to the correct battery post, so there’s no guesswork involved to make the connections. High-quality battery terminal connectors are soldered, not crimped, to the flexible 2-gauge wire connecting the batteries together.

This is an awesome system that creatively and completely adds a second battery to your JK without any major modifications. In fact, all of the factory pieces can be re-installed should you elect to ever remove the system to use on a different JK. We’re impressed with the quality of this system as well as the constructive planning behind it. If you are looking for a dual-battery system for your JK, look no further. Genesis Offroad has got you covered.

PhotosView Slideshow The factory arrangement looks like it won’t afford enough space to mount dual batteries, but Genesis Offroad found a way. The dual-battery system from Genesis Off-Road includes a heavy-duty tray to hold two batteries, the pre-wired top plate, an EVAP solenoid jumper harness for early model JKs, and extension hoses for the EVAP lines. The Genesis Off-Road dual-battery top tray is prewired and ready for installation. All that is necessary is to hook up the batteries. The included Cole Hersee Smart Isolator allows complete charging control of the batteries. It is pre-installed on the top tray. The kit includes an Evap solenoid wiring harness extension for 2007-to-2011 model JKs. The harness isn’t necessary for later models. We selected ODYSSEY batteries to accompany the Genesis Off-Road system. ODYSSEY batteries have an 8- to 12-year design life and a 3- to 10-year service life. The batteries feature welded intercell connections that enable it to withstand extreme vibration, and the AGM design holds acid in place to prevent spills, even when installed on its side. The first step of the installation was to remove the single battery from the stock tray. We then removed the relay box from its mounts and unplugged the harnesses. Unplugging and replugging these harnesses took the bulk of time for this installation. The factory air box was also removed. Once all of the bolts securing the factory battery tray were removed, we were able to pull it from the engine bay. Following the detailed instructions provided with the Genesis Off-Road kit we used a cut-off wheel to remove a portion of the factory battery tray that supports the factory airbox. Another cool thing about the kit is it can be completely removed and put back to stock if desired. The new Genesis Off-Road dual-battery tray was then situated in the engine compartment and bolted in place to the same locations as the factory tray. We still need to cut down the firewall mounting studs before installing the batteries. We then installed the airbox mount that we cut off the factory battery tray and secured it using the factory bolts. The new Genesis Off-Road dual-battery tray was then situated in the engine compartment and bolted in place to the same locations as the factory tray. We still need to cut down the firewall mounting studs before installing the batteries. The factory air box was then installed using the factory mounts. It’s necessary to lengthen and relocate the positioning of the Evap solenoid hoses. We cut the two vent hoses using a pair of tin snips and installed the provided hoses. We cut the two vent hoses using a pair of tin snips and installed the provided hoses. We installed the supplied Evap solenoid wiring harness extension between the factory connector and the solenoid. The extension harness is only necessary for 2007-to-2011 model JKs. The extension harness is only necessary for 2007-to-2011 model JKs. We then reinstalled all the connectors onto the fuse/relay box. Installation is the reverse of removal and is just as tricky. Each has to be connected blindly and in just the right order so the fuse box will properly clip in place on the mounting tabs on the new battery tray. After a few tries of routing and intertwining the connectors, we eventually got it in place for a perfect fit. We then fit each of the Odyssey batteries in to the new Genesis Off-Road dual-battery tray. With all the wiring integrated into the top plate, servicing your batteries has never been easier. You only need to pull the terminals off the battery posts, remove the four fasteners securing the lid, and all the wiring can be lifted up and out of the way to swap out your batteries when necessary. jk wrangler dual battery system

How it Works
The smart isolator provides automatic control of all the charging functions with no interaction required. When both your batteries are fully charged at 13.2 volts, they are automatically connected and are charged at the same time. When you park and turn off the engine, but continue to use accessories like lights, the stereo, or a CB, both batteries begin to drain down. When your main cranking battery reaches 12.7 volts, the smart isolator separates the batteries to ensure your cranking battery will have enough power to start the engine. The second battery continues to power your accessories for as long as it will last. After you crank the vehicle, your main cranking battery will be charged up to 13. 2 volts first, and then the isolator will begin charging your accessory battery. By only charging one battery at a time, your alternator is protected from excessive strain.

If the cranking battery is somehow drained down too low to be able to start the vehicle, simply press the Start Boost button. The isolator will connect both batteries together for one minute, acting like built-in jumper cables to jumpstart the engine using the accessory battery. As long as the combined voltage of the two batteries is at least 12.7 volts, you’ll be able to start the engine. You can also add a remote status indicator light to the dash to show when the batteries are connected and when they are both fully charged.