House batteries are what the battery system is called that is separate or mostly separate from the start battery system. Some are setup to charge from the vehicle as well as from solar panels. Some even have a provision for using shore power (a 120 volt AC outlet).
I have roughly about a 24" X 32" area to fit two 100 amp hour AGM batteries in their containment cases (about the same size as a standard vehicle battery), a DC-DC charger with MPPT (So it can charge from the vehicle as well as solar), a 2000 watt inverter, a power monitor, associated waterproof circuit breakers (a 250 amp for power from the battery to the inverter, a 50 amp for the power coming from the vehicle, and a 40 amp coming from the MPPT charger to the batteries), two small fans to cool the DC-DC charger, and a 100 amp power block with fuses for whatever. There will be 15 amp inline fuses from the solar panels to the charger but I expect they will be outside the vehicle. Wires from the vehicle to the charger, between the batteries, and to the inverter will be 4 gauge. The rest will be either 8 gauge or 10 gauge, depending on the power needs to what is being connected.
As far as the hydrogen gas generated from the batteries, there are enough open holes in the bed, plus some gaps in the Softopper to provide ventilation to evacuate the gas. If all kinds of dust can get in, hydrogen can get out. If there is a provision for hooking up a tube to the battery so that the gas can be directly vented out somewhere, I will use it, even if it isn't necessary. But I don't recall there being any.
Just in case, I will try to shoe horn a battery charger that I already have for AGM batteries in there as well. It is pretty small plug in unit (for a battery charger). It is capable of putting out 10 amps and a float charge.
Since the truck does not stay as an overlander year round, I have appropriate sized Anderson connectors on hand so I can disconnect everything fairly easily, rather having to unbolt them, and remove pieces as modules for winter storage.
EDIT: I forgot to mention, the goal is also to install everything so it doesn't block my view out the back window. There being no windows on the side of the Softopper is already a limitation. I don't want to exacerbate that by have little to no view to the rear.
Aha, now some visualization…
My ignorance. Now some slight visualization. When you said “house batteries,” I was thinking this is a system that you are installing in your house, maybe something for backup power in the event of a power outage. Now through my dim “city kid” brain, i’m visualizing a battery system so you have power in your “tent” for camping, where your tent is all that camping equipment you’ve installed in and on your truck. Yes/no?
I’d love to see the pictures as you’re doing it, I assume it will be in your build thread, yes/no?
When you were talking house batteries, I was assuming a standby system for your house. They sell those generators (for a zillion dollars on time) that hook up to your natural gas service to run your house in the event the electric power goes down. I put together the Rick F250 7.3 diesel version of that since every few years we have a big snowstorm, a real Yankee-style snowstorm, that nobody can drive through in Atlanta, and the electric power goes off.
I tied into the hot/neutral/ground that feeds my downstairs furnace with a simple three pole/single throw switch rated for the amperage ($10) which isn’t much. I’m just running the gas heat and not the air conditioning. It also ties into one duplex outlet upstairs in my master bedroom suite (computer, TV and whatever). That switch is in an outside box which has a 2ft long cord with a 110v male plug.
No matter where that 7.3 might be parked in the event of a snowstorm, I can reach it with a 100 foot extension cord. I have a 1500 W inverter on the truck. When I know the storm may be coming, I fill both tanks, 37 gallons total, and if they’re predicting a particularly severe storm, I may fill a 2-3 5-gallon jugs as well. That 7.3 burns 1 to 1.5 gph at idle, and the amperage from the inverter is almost nothing, so you can run that furnace for 37 to 50 hours on its own tanks, and another 5 to 7 1/2 hours for each 5 gallon jug. The only downside is you have to walk out in the cold and plug it in and turn the truck on. Those hour estimates are assuming that you run the furnace continuously. Depending on the storm, I would pick times of the day and cycle it, and I would only run the house at maybe 50°, and also use the fireplaces.
Of course, since I put that little system in, which only took a few hours, we haven’t had much more than a flurry or an overnight snow. Like all things, once you prepare, it’ll never happen again. Or if you say out loud “I should put in one of those systems but I haven’t had the time,” you’ll have a blizzard the next day.
Maybe somebody will be inspired to install their own Rick 7.3 system Anyway, I’m still curious about your system. Keep us posted.