We’re back at it with the Ultimate PreRunner Ford Ranger. This time we’re chasing down an old frustration while adding some future redundancies and making the vehicle even more functional. If you’ve been following this build series, you know the Ranger has been evolving in stages, upgrading suspension, lighting, ignition, and little touches that keep it reliable and relevant. Now it’s time to engineer a dual battery system.

The goal has never been to park a tube-chassis race truck in the driveway, but to create a do-it-all machine: streetable prerunner, functional race chaser, capable recovery rig, and comfortable weekend adventurer. This trusty Ford Ranger has been with me since graduating from college twenty years ago. Through all the daily drive commutes, regular truck stuff, hauling chores around, car shows, truck meets, and trips to Baja California, Mexico, it does it all. It may not be my daily driver anymore, but it’s still registered, insured, and very usable truck that meets my needs. But for the last several years, one nagging problem has haunted me: dead batteries.

When One Battery Isn’t Enough

When I first started modifying this truck years ago, a buddy and I installed a cheap race radio and an old-school Lowrance GlobalMap Baja 480C GPS system. At the time, it seemed smart to wire them straight to the battery with a toggle switch in between. That way, those necessary electronics would have power even when the truck was off. It worked, until it didn’t.

Somewhere along the line, wire connections wore through, insulation cracked, and something in the system started pulling power even with the switch off. The result was a parasitic battery draw that drained down multiple batteries over and over again till they were paperweights. At first, I carried jumper cables. Later, I added a portable jump pack. Eventually, it became an annoyance I could no longer accept.

But that changes here. With more accessories planned, more power demand, and more miles ahead, the only real solution was to install a dual battery system that separates accessory draw from the engine’s starting reserve.

Why the Optima Dual Battery System

The decision was made to go with two Optima batteries. They’re proven in off-road use, able to handle repeated discharge and recharge cycles without giving up capacity. Sometimes the truck sits for weeks at a time in between trips, and then I might use it for a couple of light trips around town. They deliver 620 cold cranking amps needed to start the Ranger’s 4.0L SOHC reliably. And there will be ample room for expansion and capacity needs in the future.

Knowing the truck will start when I need it will provide much peace of mind.

Instead of tucking them under the hood or inside the cramped Ford Ranger SuperCab, the plan was to mount both in the truck bed inside a Roam Adventure Co. Rugged Case. The Rugged Case solution would keep the batteries dry, dust-free, and out of sight while also doubling as secure storage for recovery gear, tools, and essentials.

Mounting heavy batteries in the forward bed position also shifts weight closer to the center of the truck. That’s good news for handling in a truck that’s already pushing its limits when loaded for trips.

The batteries would be secured side by side inside a RuffStuff  Dual Battery Box, which fit neatly inside the Rugged Case. Underneath, a Go Rhino Gear Plate provided a strong mounting platform bolted to the Ranger’s bed structure.

Power management comes from a Blue Sea Systems m-Series Mini Selector Switch, mounted inside the cab for quick access. For wiring, I chose the Moroso Remote Dual Battery Cable Kit along with Moroso’s crimp tool, shrink sleeves, boots, and terminal blocks to help complete the installation. High-quality parts are the only way to build a system that can handle off-road abuse.

Planning The System

Like most projects, the planning stage took longer than the actual work. My research had me looking at many similar style off-road trucks with dual battery systems. I knew what I needed, what I did not want, and most importantly, what I did want: batteries in the bed but covered, switch in the cab accessible but hidden. Figuring out the details meant a lot of thinking, measuring, sketching, and online shopping.

There were a few non-negotiables:

• Don’t drill through the truck bed floor if I can avoid it.
• Keep the install modular and reconfigurable.
• Use existing mounts whenever possible.
• Build it clean, functional, and tough enough for desert miles.

Eventually, I had a pile of parts: the two Optima YELLOWTOP D75/25 Deep Cycle Batteries, a Roam Adventure Co. 105L Rugged Case, the RuffStuff R1175-Kit-1 Dual Battery Box, the Go Rhino Accessory Gear Plate, all the items making up the Moroso Battery Cable Kit, a few miscellaneous items from Amazon, and enough stainless bolts and countersunk screws to outfit a sailboat. Now it was time to quit thinking and start wrenching.

Safety First

Before we get into the install, a quick reminder: Always disconnect battery terminals before working, wear PPE, and work in a ventilated space. A short circuit here isn’t just a spark; it could fry your vehicle electronics, or worse. Respect the process.

Mock It Up Before You Lock It Down: Dual Battery System Prep

When it all landed, I staged everything up for a quick inventory and run-through and then called in a buddy for an extra hand. We got started by mocking up the battery location and then the battery cable routing. I set the RuffStuff dual battery box inside the Roam Rugged Case, then dropped the whole thing onto the Go Rhino Gear Plate. We positioned it forward in the bed until everything looked and felt right, which was snug up close to the cab, accessible from the driver’s side, but not intruding on usable bed space.

Next, cable routing. I wanted the Blue Sea Systems selector switch in the cab, hidden but easy to reach. That meant finding a path through the firewall. I decided to utilize the OEM wiring harness rubber boot passing through the passenger side firewall. I fed two heavy-gauge positive cables through it, then tucked them under the carpet and console until they landed right where I planned the switch.

It wasn’t glamorous work, but seeing the parts staged and cables mocked up got me one step closer to checking the box on this little project.

Hammer Time: Cable Prep and Termination

With measurements locked in, it was time to cut and terminate cables. The Moroso Remote Dual Battery Cable Kit came with everything: 25 feet of red positive cable, 8 feet of black negative, copper ring terminals, and shrink sleeves.

We stripped insulation carefully, slid on the shrink, and used the Moroso Impact Crimp Tool to hammer each terminal in place. A couple of clean strikes and the connection was permanent. Heat shrink sealed it up tight. These cables won’t be the weak link.

Everything was labeled “Battery 1” and “Battery 2,” both at the batteries and at the switch end. Future me will thank present me for not leaving mystery wires behind.

Switch Control at Your Fingertips

For the Blue Sea Systems 4-position selector switch, I taped off the backside of the FiberwerX carbon center console, measured twice, and cut once. A hole saw, barrel sander, and a couple of drilled holes later, the switch clicked into place like it was meant to be there.

The location feels natural: close enough to reach from the driver’s seat but subtle enough not to draw attention. Beyond convenience, it also serves as a theft deterrent and emergency cutoff in case of fire or rollover.

Creative Mounting Solutions for Truck Bed Batteries

Even though the Ranger is pushing twenty years old, I am aiming for a build with intentional and modern functionality. Bolt-on accessories and outfitting where we can do it, without the hack. The only problem, my humble garage is lacking the metal fabrication division, tools, and skill set to design at the level we want to achieve. Similarly, the bolt-on aftermarket provisions for this commonly modified vehicle platform, which I was hoping to find, are nonexistent for this category. So, this part became a test of improvisation.

Sure, I could have taken the easy road, metal straps, self-tappers straight into the bed floor, maybe a prayer, but that’s not my style, and it wouldn’t survive the many treacherous off-road miles ahead. Armed with basic hand tools, patience, and a notebook full of half-baked sketches, I started measuring every angle of the truck bed: rail height, bolt locations, clearances, and the wheel well locations, too.

I knew the twin Optima batteries needed to sit side-by-side widthwise, not lengthwise, for better balance and accessibility. That ruled out most machined aluminum trays designed for oval-footprint batteries. The RuffStuff R1175-Kit-1 Dual Battery Box ended up being the perfect fit, 12-gauge steel, laser-cut precision, tight tolerances, and a widthwise layout that matched these YELLOWTOP D75/25s squared edges. Additionally, the design allows to have either one or both batteries to be installed independently of each other. It’s overbuilt in the best way and gives the whole setup a professional, motorsport-grade look.

A Modular Dual Battery System Foundation

Next came the base. I needed something sturdy enough to mount the Roam 105L Rugged Case and the battery tray together. After too many late-night searches, the Go Rhino Accessory Gear Plate looked ideal, flat, rigid, and roughly the same footprint as the case. I could use Roam’s rigid mounts to secure the case and possibly sandwich the RuffStuff tray to the plate below. It was a bit of “Minecraft engineering” on paper, but the geometry worked.

The last mystery was how to tie the Gear Plate into the Ranger’s truck bed. I went hunting for heavy-duty brackets or something that could bridge the gap between the plate and factory bed bolt points. Eventually, I found 6-piece Z-shaped corner braces on Amazon meant for industrial shelving. The reviews mentioned people using them for roof racks and other overlanding necessities, so I figured, why not? The material specs were up to snuff, and they definitely looked stout.

Once all the parts arrived, I spent a solid evening dry-fitting everything: bracket to bed, plate to bracket, Rugged Case to plate, battery tray inside the case. In the end, it came together exactly like I had pictured. There was even a bit of leftover plate real estate for future accessories, maybe an off-road jack at some point. For now, I will be securing a Rusoh Eliminator fire extinguisher for emergencies.

Dual Battery System Hard-Mount Prep

When the RuffStuff Optima Dual Battery Box showed up, I was supremely impressed with the quality and construction. All the laser-cut edges were precise and square with no crust or burrs left over. The middle partition and nuts were cleanly welded on solid, and the tolerances were tight. The overall design left me more than satisfied, knowing the price to purchase was a great value. This wasn’t a rough-cut shop piece; it looked like something you’d find situated on a legit off-road race vehicle.

I’d ordered a 151-piece M6 stainless hardware kit consisting of countersunk bolts, washers, and nuts, plus a Cobalt M35 countersink bit for cutting perfect chamfers into the tray. I wanted the bolts to sit flush, no snags, no rattles, nothing that would inhibit the batteries from sitting flush.

Out came the cardboard templates and tape measure. I mocked up the RuffStuff tray inside the Roam Rugged Case, which sat on top of the Go Rhino Gear Plate. A few rounds of scribbling, measuring, and checking clearances later, I marked the final hole patterns for the battery tray. With a little Lucas Oil Tool Box Buddy for cutting lube, my tired cordless drill managed the pilots, but I pulled out a big plug-in drill to do the heavy lifting. By the time the fourth hole was countersunk, I’d turned the tray into a custom piece that mated perfectly with the plate.

A Durable Protective Coating

Once the drilling was done, I wiped down the tray and other items with acetone and then applied a layer of black polyurethane STEEL-IT coating. This finish adds corrosion resistance and ties the look together with matte black on the rest of the build. It is functional and slick without screaming for attention.

While the protective coating cured, I prepped the bed hardware. Anticipating seized bolts, I soaked every OE bed mount with WD-40 Specialist Penetrant overnight. The next morning, the old bolts broke loose with a groan and some elbow grease using a breaker bar and a Torx T55 1/2″ S2 Steel Star Socket tightened down, it looks very sturdy and purposefully assembled.

Unfortunately, the new truck bed hardware kit I also purchased was not a direct fit, so we reused the OE stuff, which went back in without drama. This is when the real fun started. We began lining everything up for assembly: brackets, plate, Rugged Case, and battery tray.

Outfitting The Dual Battery System Rugged Case: More Than Just Batteries

The beauty of using the Roam 105L Rugged Case is the one-sided alligator lid opening feature. I can operate the latches and open or close the case from just one side of the truck without having to access the other side. Besides that main design provision, the Rugged Case doesn’t just protect the dual battery system. It doubles as a gear locker for everything I want close at hand.

Roam offers a variety of accessories designed specifically for the 105L Rugged Case. The 105L Rigid Mounts are a must for easy mounting, and I also opted for the 105L Lid Organizer to keep the little stuff sorted, like first-aid kit, tie-downs, hardware, and everything else. I might consider changing that out for the 105L Molle Panel, or figure out a way to run both at the same time.

More Gear

Inside the case, besides housing the batteries, I can throw in the various off-road recovery items, a Boxo 80-piece tool roll, which fits neatly inside, and keep it on hand, ready for trailside fixes. A Gerber Bushcraft axe mounts with Quick Fist clamps and will be perfect for clearing a downed limb or splitting camp wood.

Security matters too, so I decided to lock down the Roam Rugged Case with a BOLT-Lock stainless padlock keyed to the Ranger’s ignition. I also run the BOLT-Lock cable lock for everything else outside the box.

Lighting? That’s still a work in progress. I might configure a small LED light to illuminate the case when I flip open the alligator lid. Until then, the BioLite Range 400 headlamp lives in the organizer. It’s what I grab the moment the sun goes down, and it doubles as my hands-free light for night work around camp.

The result is a multifunctional box: dual battery power, secure gear storage, and organized trail essentials all in one footprint.

Dual Battery System Final Assembly and First Test

The trick throughout this whole assembly process was to take our time and just think it all out. To make sure we got it right, there was a repetitive process of setting up, mocking it into place, checking clearances and alignment, and then finally fastening it all together. Check out the step-by-step installation in this detailed gallery.

My only gripe is that getting any hardware underneath the Go Rhino Gear Plate was a bit tricky and very tight. With some long skinny arms, it was all manageable. Tightened down, it looks very sturdy and purposefully assembled. Here are the batteries in their final resting place.

With everything mounted, wired, and labeled, it was time to connect the system. The selector switch offers four modes: Battery 1, Battery 2, Both, or Off. Testing each position confirmed our arrangement was correct, accessories drew power without issue, and the parasitic drain was history.

A few days before final battery installation, I took the extra step of conditioning the batteries with an Optima 12V Battery Charger 1200. Both YELLOWTOP D75/25 Deep Cycle Batteries were connected to trickle-charge overnight and throughout the next day. The Digital 1200 is designed to optimize Optima batteries specifically, balancing voltage across each cell for maximum lifespan and performance. After sitting on charge, both batteries measured strong and stable, a perfect baseline for the new dual battery system.

The Rugged Case shut tight, cables routed clean, and bed space remained usable. It felt like the Ranger leveled up from an aging truck with nagging problems to a legitimate adventure rig with a thought-out electrical system.

Fully Charged and Finally Grounded

Did I make this harder than it needed to be? Totally overboard! Between overthinking the plan, sourcing parts, improvising brackets, and measuring things five times before drilling once, the install dragged out longer than a simple strap-and-bolt job would have.

But the end result is worth it. The dual battery system replaces the single battery configuration, moves the batteries for optimized weight distribution, adds a lot more battery capacity with redundancy, and ultimately resolves a nagging parasitic draw, all while future-proofing the truck for more accessories. The Rugged Case approach kept the install clean, modular, and functional as a gear locker. And the process itself, messy, frustrating, and rewarding, is exactly what makes building a project truck worthwhile.

At over 170,000 miles, the Ranger is still evolving. The next phase will tackle modern wiring with a multi-channel switch controller, configuring some much-needed off-road lights, a few modern conveniences, and even more reliability upgrades. For now, though, I can finally turn the key without holding my breath. The Ultimate PreRunner is fully charged and ready for whatever’s next.