J A N U A RY • F E B R U A RY 2 0 1 5 Adding a second battery created even more complications. My biggest concern with the added battery was in knowing the exact condition of each of the batteries. All the factory gauge does is tell me the voltage while they are both hooked up in parallel. The only way to really know just how much life my batteries have left is to use a voltmeter. But what I needed was a way to check the batteries individually, as well as a way that didn't include needing to turn on the ignition key. Plus I really didn't like the idea of having two individual voltmeters even if the dash space was available. The driving force behind the need for this is my fridge. When we go camping, our fridge needs power but not at the expense of the ability to start my rig the next day. What I came up with is extremely simple and has no draw on the system when it is not being used. All it takes is a bit of wire, a single voltmeter and a toggle switch. Let me start by saying that not all toggle switches are the same. My toggle switch is a bit different, as it has three positions. In the center is off and to either side there is a momentary on. Essentially it is springloaded to the off position. This means that you have to move and hold it to one side to activate that side of the circuit. Hold it to the left and you get a reading for the driver’s side battery; to the right is the passenger side. In the Cole Hersey catalog, it is listed as a momentary on-off, momentary-on switch. If you don't use this type of toggle you will have a small draw on the system at all times. To make this all work, a wire is run from the hot side of each battery (or in my case, on the terminals on the back of my main battery switch) to the outboard terminals of the switch. The center terminal of the switch runs to the 12V connection of the voltmeter. Holding the toggle to one side or the other now activates the voltmeter and gives you the reading for the chosen battery. Releasing it puts it back in the off position. You can now check the voltage of an individual battery while parked with the key off to see how much juice is left or when running to make sure it is getting charged. And just so the lights of the gauge don't make me nervous with a voltmeter on zero, the lights are wired into the center post of the switch. This way, the light only comes on when you are checking a battery. This setup has prevented me from killing a battery on more than one occasion. And chalk up another one for clean, simple and bulletproof. PHOTO BY TONY KONOVALOFF 43