Dual Battery Setup - Off Road Magazine

It's one of the essentials for off-roading - make sure you have a dual-battery setup! Most people add a second battery to their vehicle when they start adding lights, big stereos, and winches. This is smart, but really, they could get the same end result by just putting in a bigger battery that had a longer reserve capacity. So why bother with two batteries and the extra wiring? The real reason to have dual batteries is in case your main starter battery dies out, and you need to jump your main off of your auxiliary battery. The biggest/only problems with dual batteries are the space occupied by the extra battery and the weight (two typical dry-cell battery will weigh over 100 pounds!)

The PC680 weighs in at only 15 pounds and has enough amperage (680 PHCA, 220 CCA) to turn over a big V-8 engine. It has a very small reserve capacity (24 minutes) but is enough to keep a factory vehicle's electrical system alive.
The PC680 weighs in at only 15 pounds and has enough amperage (680 PHCA, 220 CCA) to turn
Power-Gate Isolator50-400 amps (continuous) capacity8-30 VDC99.8% efficiency at full current50-150 millionths of an ohm (ON-resistance)18.56 oz
Power-Gate Isolator50-400 amps (continuous) capacity8-30 VDC99.8% efficiency at full curre
This is Perfect Switch's Power-Gate, and it really is a perfect switch. It can be ordered in a number of configurations, but we got ours as an isolator for our dual-battery setup. These switches are about the most high-tech piece of electronics you can buy for your truck, and we'll direct you to the company's website
This is Perfect Switch's Power-Gate, and it really is a perfect switch. It can be ordered

But Odyssey had a solution for us. We remembered seeing one of its company trucks run solely on a PC680 battery - a tiny battery that looks like it came out of a motorcycle and it weighs in at only 15 pounds. Together with a PC1700 (weighing in at 60 pounds), we would only have a combined weight of 75 pounds of batteries. We would use the PC680 as the main (starter) battery, and use the PC1700 as the auxiliary battery, attaching all our accessories to the auxiliary battery.

But what about connecting the batteries together and controlling the isolation? You could just hook up both batteries' positive leads together, but then you have no isolation abilities and are really no better off than just having a bigger single battery. This is where a dual-battery kit with a relay or some other type of isolator becomes necessary. Our isolator of choice? The Power-Gate from Perfect Switch. It is the ultimate isolator and rectifier in one small package. There is little-to-no voltage drop with it, and it does not generate the heat (heat equals power loss) that other isolators/relays do. It's totally automatic so we don't have to worry about switches, and it acts as a perfect one-way electrical valve.

This is how we had our system planned. The main battery (our PC680) will handle all the factory engine equipment, and we will hook up all our accessories (winch, lights, and stereo) to the auxiliary battery (the PC1700). Often in a dual-battery setup, you would connect the main battery to the alternator. But since the Power-Gate only flows power one way and is always on, you isolate out the main battery (used for engine duty) on the cathode side. As long as the voltage is higher or the same at the anode side, power will continue to flow from the anode to the cathode through the Power-Gate.
This is how we had our system planned. The main battery (our PC680) will handle all the fa
We mounted our Power-Gate in a secure location (always best to keep electronics as far away as possible from dirt, water, and heat) and connected the ground wire first (as directed). Next, we hooked up the auxiliary battery and alternator (anode side) and then the main battery (cathode side). The Power-Gate comes with red cover boots that slide over the terminals to keep them protected.
We mounted our Power-Gate in a secure location (always best to keep electronics as far awa
Two Group 34 (the most common size) dry-cell batteries weight about 100-110 pounds together (50-55 pounds each). A single PC1700 Odyssey battery weighs about 60 pounds and offers more than enough cranking amperage and reserve capacity to supply the engine, stereo, winch, and off-road lights without ever really being an issue. The only problem with running one battery is when we leave the stereo on too long or run the winch too much without the engine on, and we don't have enough juice to turn the engine over (with the starter) when it comes time to drive away.
Two Group 34 (the most common size) dry-cell batteries weight about 100-110 pounds togethe

Running a small and large battery like we are doing allows for some weight distribution. Since we're putting this setup in a prerunner, we want to lessen the weight of the truck up front and would benefit from some extra weight in the back. We pulled out our old PC1700 from under the hood and replaced it with this PC680 held by West Coast Batteries' aluminum battery hold-down, which you can mount directly on the firewall or fender of your ride. By doing so, we dropped 45 pounds out from under the hood of our ride. We ordered the optional threaded-brass posts of our PC680 and connected 2.0-gauge battery cable to it to run to the Power-Gate and back to the auxiliary battery. We used a 4-gauge power cable (the size the OEM used) to connect the battery to a distribution block powering our factory electrical system.
Running a small and large battery like we are doing allows for some weight distribution. S
We threw our bigger auxiliary battery (the PC1700) in a large battery box mounted in the bed of the truck (the battery is sitting next to the box for picture purposes) to add some weight in the rear of the truck where we needed it. The positive lead was connected with 2.0-gauge cables to run from the battery's positive lead to the anode of the Power-Gate. The negative ground was attached to the frame. All our accessories (the winch, lights, and stereo) will get connected to this auxiliary battery. Should the battery ever be drained of power, it will not pull any from the main battery, allowing you to always have a starting battery (in our case the lightweight PC680).
We threw our bigger auxiliary battery (the PC1700) in a large battery box mounted in the b