Chapter 11: Battery Combiner Charging System
One thing I have learned is that solar is iffy in the south. You are always camped under trees, which cuts into your power production mightily. Giving your battery the abilty to be charged from the truck is a beautiful thing, especially in conjunction with a solar system. Theoretically, when you're parked, you will get a little charge from the solar panels, and when you're running, you are charging. Also, when the camper is stored or parked, the solar system will be working. All in unison, the battery should be topping up all the time. Plus, it's smug to think that while I'm in the grocery store buying beers and burger meat, out in the parking lot my solar panel is working hard enough to hold up my fridge with enough surplus to be banking a little extra energy. Well, the solar panel will come later, but for now we can start with the Battery Combiner system.
I actually have a 3 battery system in my truck. There's the truck's own battery, then I have a little 35 AH AGM battery, also mounted under the hood, and then there is the camper's battery. The 35 ah battery is for camping in the truck without the camper. I have 12v sockets run from the 35 AH battery into the passenger side extra cab, through a factory-provided grommett hole, and then on back to another socket in the truck bed. This is for my Dometic CF-18. The CF-18 is a conventional cooler style, top opening 12v compressor fridge I've had for a few years. I can run it inside the cab, or in the bed.
I bought a
Magnum Power Smart Battery Combiner to control charging of the extra batteries. It works like this: It's connected to the truck's battery with a #12 wire. I have all of my stuff wired 2-wire style. I don't trust chassis ground. The combiner is also connected to the 35AH battery. When the truck is running, the combiner senses the voltage, and when it reaches a preset point (about 13.2v) it combines the batteries together, thus charging the secondary battery. When the truck is shut off, it again senses the voltage drop, and disconnects the two batteries, thus isolating the two systems. When it came time to add the camper's battery to the mix, I just cut off the 12v plug I had running to the bed (#12 wire), and installed some Anderson Powerpole connectors to the end. Also to the end of the 12v socket (so I can put it back on) and ran a #12 wire to the camper battery (an 85AH deep cycle, by the way). Now, after I back under the camper, hook up the chains, and plug in the connectors, I'm off with my alternator charging all 3 batteries at once. If I "space out' and forget to disconnect the combiner wires when I take the camper off, no worries, the Anderson connector detaches gracefully. Golden.
Now, geeks might call me out on a few things, like #12 wire being too small, voltage loss, combining 2 battery types etc. etc. but at the end of the day it's working pretty well. The Magnum system charges the little 35AH battery to 14.1V, but voltage loss in the 18 feet of #12 wire to the camper battery drops to around 13.2. I'll point out that it's important that you charge your battery with a good quality 3 stage charger every so often, to about 14.2 volts so it will last longer. Other than that, it's a camper for personal enjoyment, not an ICBM that we rely on to defend our United States. And batteries are cheap enough that I won't fret about replacing them every 4 years or so.
Nice work! Was the framing around the door still solid? Will have to remember Emmet Door when it gets to that time. Back in the states and just picked up my "new to me" popup. Will be listing my old home soon.....
