Upgrade the Jeep JK Charging System with an Optima Yellow-Top Battery

    Deep-Cycle and Sealed Glass-Mat Designs Combine To Maximize Winching And Auxiliary Electrics

    Tom MorrAuthor

    The Jeep JK Wrangler was a huge success and helped popularized the legendary brand. Electronics additions such as LED bars, winches, and exotic entertainment system emerged as some of the most popular upgrades. Those electronic upgrades can placed so much stress on a factory battery, that one of those electronic upgrades should be a premium deep-cycle glass-mat battery like the Optima Yellow-Top.

    Our 2007 JK has a variety of aftermarket electronics. Factory cables are shrouded in split-loom tubing. The two heavy-gauge cables are the winch leads.

    In older vehicles, adding a second battery was a common solution for keeping up with increased electrical demands. Packaging is a challenge on newer vehicles: unused space is at a premium, and many Jeepers hesitate to sacrifice cargo area to an auxiliary battery. An easier first-step solution is to upgrade the battery in the engine compartment, followed by a higher-output alternator.

    Consider taking a photo of the existing cable configuration for reference prior to disassembly. Then remove the negative leads from the terminal clamp. This will prevent inadvertently arcing the positive terminal to the vehicle's body. Also, removing the individual leads from the clamp allows them to be inspected for damage.

    Veteran Jeepers are generally aware of Absorbed Glass Mat (AGM) batteries, popularized by Optima. Unlike traditional "flooded" batteries, AGM uses mats to hold the acid electrolyte in suspension. This makes Optima batteries maintenance-free, virtually spill-proof thanks to their sealed design, accept higher charge amperages, resistant to shock and vibration, and produce more power from a smaller package.

    We unclipped the emissions canister from in front of the battery and moved it aside to assist photography and clearances. The factory terminal clamps will be transferred to the new Optima battery.

    Standard batteries are designed for SLI duty: starting, lighting, and ignition. These functions typically discharge the battery less than 5 percent, primarily during starting. When the battery is cycled deeper than that level, its lifespan starts decreasing. The more a standard battery is deep-cycled, the shorter its life.

    Similarly, unbolt the positive cables and terminal clamp. Then, a ratchet with long extension is handy for removing the battery hold-down bracket.

    Deep-cycle batteries evolved for marine and RV applications, where the power demands routinely exceed the approximate 5-percent discharge rate required to start a vehicle. The off-road community embraced this battery style - winching and overlanding-inspired 12-volt accessories can discharge batteries by 60 percent or more. Deep-cycle batteries use internal plates that differ from standard SLIs' to better accept discharge/recharge cycles with less affect on lifespan.

    To further increase working space, gently lean the hood against the windshield and secure it there instead of resting it on the prop-rod. Then the old battery can be easily lifted out.

    For our "Week To Wheelin'" 2007 JK, an Optima Yellow-Top deep-cycle battery was a perfect charging-system upgrade to optimize performance of the winch, higher-output LED headlights and taillights, and other electrical add-ons. While the standard Optima Red-Top is an upgrade over the factory-spec battery, an extreme winching session with a standard battery revealed that a deep-cycle Yellow-Top model would allow the 12-volt add-ons to perform their best the longest. The Yellow-Top is designed to withstand more than 300 discharge/recharge cycles.

    The replacement Optima Yellow-Top deep-cycle battery includes handy snap-in post covers that work with side-cable routing. Our JK's cables enter from multiple directions, so the covers won't be used here.

    For our JK, we also discovered an Optima power upgrade. A direct-replacement Optima Group 34 size is available for the earlier 3.8L JKs like ours, but the larger, more-powerful H6 fitment for the later 3.6L Jeeps will fit first-gen JKs. The posts are reversed, but the factory cables are long enough to span the additional distance.

    The positive Optima cover also includes a detachable plug for vehicles with venting systems (which our JK doesn't have). Refer to Optima's instructions for details.

    Battery Comparison

    OE Mopar Optima Yellow Optima Yellow
    Group Size 34 34 H6
    C20 Capacity 67 Ah 55 Ah 72 Ah
    CA N/A 870 928
    CCA 700 750 800
    RC 120 mins. 120 mins. 140 mins.

     

    C20 Capacity: A measurement of the battery's electrical storage capacity.
    Cranking Amps (CA): Amps a battery can deliver at 32 degrees F for 30 seconds and maintain at least 1.2 volts per cell.
    Cold Cranking Amps (CCA): Amps a battery can deliver at 0 degrees F for 30 seconds and maintain at least 1.2 volts per cell.
    Reserve Capacity (RC): Number of minutes a battery at 80 degrees F can be discharged at a 25-amp rate until reaching 10.5 volts and maintaining 10.5 volts.

    Optima offers a direct-replacement Group 34 size for the earlier JKs with the 3.8L V-6. However, we discovered that the slightly larger, higher-output H6 size for the later 3.6L V-6 models will fit the first-generation JK. The H6's terminals are reversed, but the factory cables are long enough to reach.
    Thankfully, handles are standard on all Optima batteries and many other replacement models. It expedites lifting the battery into a lifted Jeep.
    Installation reverses the removal procedure. This slightly larger H6 Optima had to be wiggled on the tray to align the factory hold-down bracket.
    The factory cables have locking tabs that align with the terminal clamps. We found it easier to route and bolt the majority of the cables to the clamp before securing the assembly to the battery.
    Luckily, all cables were long enough to facilitate the larger battery's post-reversal. Verify routing and clearances before securing the terminal clamps to the battery posts, negative side last.
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