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Project Over/Under: Part 9- Adding Dual Batteries and a High-Output Alternator

Project Over/Under: Part 9

Apr 3, 2019
Photographers: Jeremy Cook
After around 11 installments, it’s hard to believe we’re finally just about finished with our overland-style project. One area we’ve wanted to cover since the beginning was the charging system. This truck has never had a problem, but we did add a big stereo, LED lighting, an alarm, and a USB charging station in the bed area, so we really had to upgrade the truck.
Properly adding a dual battery kit requires a bit more than a second battery. You need to mount that second battery, run cables to it, and have a way to isolate it from the other battery. That’s the real benefit here: being able to power the truck throughout the day or night when you’re out on the trail and still have a fresh battery to start it when needed. There are simple isolators on the market that are simpler than what we were planning, but when we threw a high-amperage alternator into the mix, it rendered them obsolete—they can’t handle power!
So, while our final parts list was bigger than we planned, we were confident we were doing the job right. For the two new batteries, we looked to Odyssey for a couple matching Extreme Series 78-PC1500s that would fit into both the stock location and the factory-style auxiliary battery tray we picked up off eBay for a few bucks. Then we called up Powermaster Performance, because we knew it carried a 220-amp alternator that bolted right into the stock location and had the correct plug and pulley. To make it all work, we discussed our needs with Painless Performance, who recommended its weatherproof dual-battery control system, which consists of an extreme-duty solenoid and three-way switch along with all the other connections. Finally, Painless added 16-foot lengths of 1-gauge cable to cover all the cable we were adding or replacing. We completed the job in a couple afternoons and were soon enjoying the fruits of our labor, feeling confident this truck is one giant step closer to being the reliable off-road cruiser we envisioned form the beginning. Follow along and check out next month for what we think will be the final installment of Project Over/Under.
Photo 2/34   |   The first step of a dual-battery install story is acquiring two batteries. Odyssey’s Extreme Series 78-PC1500 batteries fit the bill perfectly with their 850 cold-cranking amps, side terminals, and factory fitment for our Silverado.
Photo 3/34   |   The Painless Performance Products 250-amp weatherproof dual-battery control system (40103) and 16-foot 1-gauge positive and negative cables looked like more than we wanted for the job at first, but the more we researched, the more we realized this was what it took to do the job right.
Photo 4/34   |   Odyssey also sent us its 20-amp portable battery charger (OBC-20A). It features rugged construction and will be put to good use maintaining our Odyssey batteries between adventures.
Photo 5/34   |   The Powermaster 220-amp vehicle-specific alternator in natural finish was exactly what we were looking for to make some power on the road. Probably more important than that 220 number is the fact that this alternator makes 150 amps at idle!
Photo 6/34   |   We really wanted to use the cool aluminum battery box offered by Odyssey, but in the end we grabbed the factory-style auxiliary battery tray that’s widely available online.
Photo 7/34   |   Here is what the rear passenger-side area of our 1500 pickup looked like stock.
Photo 8/34   |   The first item to go was the factory fender brace.
Photo 9/34   |   The auxiliary battery tray needed a little bend but quickly dropped into place and was locked down with all the same factory hardware.
Photo 10/34   |   We went ahead and set the Odyssey battery in place and snugged it down with the factory hardware.
Photo 11/34   |   Next, we moved to the stock alternator, which was clearly the 15-year-old original. We removed the factory plug along with the charge wire.
Photo 12/34   |   After hitting the tensioner with a breaker bar and socket to remove the belt from the alternator, we removed the two bolts that hold it in place.
Photo 13/34   |   A minute later, the Powermaster unit was in place and snugged up.
Photo 14/34   |   We replaced the belt and reattached the wiring, then tested the alternator before moving on.
Photo 15/34   |   The stock battery was removed and the area was cleaned up for the Odyssey replacement.
Photo 16/34   |   The Extreme Series battery was dropped in and bolted in just like stock.
Photo 17/34   |   We had to find a place to mount our heavy-duty Painless solenoid, and these two grounding studs on the firewall looked like they were made specifically for the job.
Photo 18/34   |   At this point, we started measuring for our positive-side cables and cutting them with a cutoff wheel. Then we used a vise to secure the 1-gauge copper terminals in place. We made one that ran from the auxiliary battery to the isolator, and another that ran from the isolator to the factory junction block. We also ran a negative from the auxiliary battery to a threaded hole in a body mount on the frame below.
Photo 19/34   |   With the Painless isolator bolted to our factory grounds and the ground wire attached, as well as the fuse link we would be using later, we then hooked up each of the cables to their terminals on the bottom end. It’s just like any Ford-style isolator you’ve seen—just twice the size and twice as reliable!
Photo 20/34   |   We found a perfect solution for our alternator charge wire at the local mom and pop auto parts store. It was 12 inches long and 4 gauge as opposed to the factory 8-gauge wire.
Photo 21/34   |   The factory junction box seemed plenty beefy, so we retained it to make life a bit easier. It’s where the factory battery cable merges with the alternator on its way to the starter. We opened up the holes for the isolator wire and our new alternator charge wire with a die grinder.
Photo 22/34   |   The remaining items are all to control the isolator from the cab. The custom Painless three-way switch and indicator lights make this much easier than trying to piece it all together yourself.
Photo 23/34   |   For switch mounting, we chose a blank space on the dash above the passenger airbag switch. So the first thing we did was remove it.
Photo 24/34   |   We drilled a ½-inch hole in the dead center of the area for the switch body.
Photo 25/34   |   Then we drilled a 5/16-inch hole on each side of the switch for the indicator lights—in the wrong place at first. We’ll be ordering this piece and doing this step again soon.
Photo 26/34   |   We wired the red and green lights together and taped them up, leaving only a ground and the three wires that travel to the engine compartment.
Photo 27/34   |   A nice big steel section under the dash was used for the switch ground. Then we routed the other three through a hole in the firewall we previously used for the audio power cable.
Photo 28/34   |   Back in the engine compartment, we routed the yellow and brown wire to the isolator. Yellow attaches to the small positive terminal and the brown simply attached to the fuse link we previously installed.
Photo 29/34   |   For the isolator to work correctly, the green wire needs to attach to power that’s only on in the “run” and “start” positions. We found a spot in the fuse box after just a couple tries. Pro tip: Use one that says “ignition”!
Photo 30/34   |   We picked up a fuse tap and wired up our final wire. Then we routed it out of sight.
Photo 31/34   |   With everything else in place, we connected our cable from the isolator to the junction block.
Photo 32/34   |   Then we connected the terminals on the auxiliary battery, which were all zip-tied in place and looking good after the system was tested. Finally, we reconnected the main battery.
Photo 33/34   |   The red and green indicator lights lit up as promised…we just had the switch upside down. We’ll flip it when we replace the plastic housing we messed up! But basically, no light isolates the auxiliary battery, the green light connects the auxiliary battery while the ignition is on, and the red light connects the auxiliary battery at all times.
Photo 34/34   |   Our engine compartment definitely looks more purposeful, and we’re confident we’ll get many years out of our heavy-duty charging system. The Powermaster, Painless, and Odyssey components really came together for a stellar charging system.

Sources

Painless Performance Products
817-244-6212
www.painlessperformance.com
Odyssey Battery
Reading, PA 19605
888-422-0317
http://www.odysseybattery.com
Powermaster Performance
West Chicago, IL 60185
630-957-4019
http://www.powermasterperformance.com

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