Charge controller and electrical system review

[Bluesky]

My bus is currently set up for just boondocking, sort of. There is a spot for two batteries and wiring to the water pump and house lights. The roof A/C, 2-way fridge, and Oven light have A/C cords. I’d like to add a charger and a hook up for shore power for now and a generator at some point. Solar would be cool too. I’m thinking about a 35 Amp convertor/charge/distribution panel, would that be enough? The roof air is 20A. Add fridge, water pump and lights and it’s 33 Amps. I’m not sure what the draw to charge the battery or how the lights and water pump factor in. I suppose they will run off the battery until it gets low enough to trigger the charger. With 20A to the airconditioner, the 35 Amp power panel will have 15 Amps left for everything else. I plan on having one or two batteries, what is the typical demand for charging? The description for this power panel isn’t clear about what it can do, WFCO brand.

[JDOnTheGo]

Get a Kill-a-Watt meter from Amazon and measure your power consumption. Perform an energy audit (or budget) and you will know how much power you need each day. No need to guess.

[Bluesky]

Thanks for the reply, but I’m not sure how to apply that to this situation. Basically I am building the power system from scratch. Based on the specs for the air conditioner DuoTherm: Model 57915.331 20Amps 3.5KW gen.
I’m considering the Sportsman 4000 propane generator 4000 surge watts/3250 running watts.
I read on Batterystuff website “It will depend on the efficiency rating of the charger/converter power-supply you intend to use. Once you find a brand that you intend to use look to their AC Input ratings. The AC voltage x AC Amperage = The Wattage. The Wattage rating has to be below your continuous run rating of your generator.”
So with that 3250W/120V = 27.08 A so an power panel rated about 25 A?
Taking into account the rest of the appliances, the fridge Dometic Model RM 36a 1Amp,
Water pump may be 4A, Lights total may be 8.5A. I don’t have a kill a watt, but I’ll check the A/C with a current clamp, and I’ll have to borrow a car battery to check the dc draw of the pump and lights with a DMM.
I’d like to get the power panel first and get the batteries later, am I limited to a 25A panel if I intend to get the 3250 W generator?

[BlackJohn]

So any place you may stop and go on shore power, you need a minimum 30 amp setup. So that's where your build starts.
Offered will be 30 amp and 50amp services in an rv setting or anywhere you stay in North America.
So pick one. Build to that standard or greater for the difference in cost.
Always oversize not undersize with electrical components no matter what they are, switches, panels, chargers, appliances etc.
Sounds like you should build it for 50 amp service and a panel with as many circuits as you can find, both dc and ac circuits.

Install it where you want it and wire whatever it is you need. One piece at a time gets it done.


John

[Bluesky]

Yikes! I’ll avoid the 50A setup. I’m still trying to wrap my head around the math to determine how everything works together before purchasing costly components. I currently have the roof air connected to my house via a 100’ 10-gauge 20A extension cord connected to a 20A breaker. The roof air draws 10 to 20Amp according to the current clamp. I realize this is less than optimal, but it works.
The generator I’m considering can supply 3250W/120V = 27.08A continuous and 4000W/120V = 33.3A surge. The roof air draws 20A. Fridge 1A, Stove and oven have a light 1A, and that’s all for the A/C side for now anyway. That’s 22A.
I went to Camping World to look at power panels, but they had none on the shelf. I thought I could get the Input rating off the box since I couldn’t find it on the manufacturers website. If I look at the description of the WF-8735 model converters provide 35 Amp DC output, and a highly reliable nominal 13.6 VDC with or without a battery. So, 35A x 13.6 vdc = 476 W. From that I figure 476W/120vAC = 3.97A this doesn’t include the efficiency or losses of the convertor so I could say 5A A/C going into the power panel yields 35A dc output.
The dc appliances include Water pump 6A, Three 1141 bulbs in the kitchen, bathroom, and step rated at 18.4W/12.8v = 1.44A x 3 = 4.3A . Two Edison Screw bulbs in the dining area, and bedroom I found an led version rated at 4.5W/12.8v = .35A x 2 = .7A. A toal of 5A for the lighting. The stereo may be 1A. so 12A dc total, that’s less than half what the power panel is rated for.
22A plus 5A convertor = 27A, should be doable with that generator or 30A shore power. This at least gives me a baseline to work from, that is if I’m on the right track. Does anyone see anything off in this math? This system leave little wiggle room, but is not too far off. Still unknown is battery charge.

[Bluesky]

I guess the math is valid. I decided to go with the Parallax 6730 power center. It has a 30A main breaker and 15A breaker for the d.c. convertor. There is a 20A breaker I’ll wire to the roof air, and another 15A breaker that will supply the fridge and A/C outlet. There are 5 d.c. circuits. I’ve updated my schematic for now. The power center includes a 3-stage charger for the battery. I have an inverter that will remain off unless I need it while boondocking. I’ll add a switch for the stereo to power from the engine battery while driving, or the house system while stationary. The range lighting, I’ll convert to 12V. I have maxed out the power center before even hooking it up, but it will provide enough for this system. The propane appliances do not have electronic controls. I’m interested in solar, so I want to make the system as efficient as possible. I would like a stainless steel power inlet and the only one I find is 30A, so I will use that. In the future I’ll add a generator and solar too.