12v vs 120v?

[Diesel Dan]

I'm not quite ready to do the electric yet, but am thinking ahead... If you have the choice, which type of electric components are preferable? 12v or 120v? Does it depend on usage? Perhaps the price of the inverter/converter thing that changes one to the other? For a cheapskate like myself, which would ultimately be cheaper to install and run?

Seems like I have a choice to make regarding things like lighting, sound system, etc. I'm not even sure what options I might have regarding the A/C, refrigerator and other appliances. I'm currently thinking of getting a rooftop A/C, are those 12v?

I don't really know yet how often I will be plugging in at a campground's shore power, vs. using my own battery power when parked. I don't think I will have a generator, at least not at first...

Any thoughts?

[the_experience03]

Usage is just it. MY bus is exclusively 120vac. I still have the lights up above the windows on the chases, but those can't operate without the ignition on. They're convenient if I'm just moving the thing around or whatever and don't want to turn on the inverters, but are otherwise never used. I just assessed my needs and found that the inverter route was going to be much easier for me. The wiring is also arguably easier. Wire and switches rated for 120vac use are much easier to find than DC rated switches or the horsecock wire large loads require. But...I do subject myself to inverter loses. The worst is that I still haven't gotten around to wiring in a few cigarette lighters here and there so I plug an adapter into an outlet being fed 120vac from my 12 volt powered inverters to get...12 volts. Funny...my bus came with an ashtray (used at that) but no lighter.

[sportyrick]

everything on my bus is 12v except the air cond and microwave, I wouldn't have it any other way. Bought a 12v flat screen Digital TV with DVD player, it's great and we even put it outside to watch a football game. I have a small inverter for 110V when needed or have generator to use if needing more power. You can even charge your batteries with solar power if needed if you are low voltage. Stay as far away from high voltage if you can and you will be happier. sportyrick

[Diesel Dan]

Hey, Sportyrick! You're like one of my skoolie heros! I was first captivated by your moving the door to the midsection and putting in a passenger seat up front, and then saw your two-part A/C idea, and of course relevant to this thread is your "OCD control panel". That is some great stuff man! I guess it helps that you're a welder. I might need to acquire that skill if I'm going to do much fabrication on my bus.

So how does your primarily 12v system work when you have the option of plugging into shore power? Does the 110v shore power recharge your 12v batteries? Is your bus wired to convert the 110v to 12v so you don't have to use up your batteries when you could just plug into the shore power? Seems like if you are paying for the 110v at a campground, you might as well use it, right?

[sportyrick]

thanks diesel dan! Now I have to remember what is what. I have a generator, shore power and of course 12 volt. Now my OCD panel has 3 220V outlets in it and ONE 220V PLUG which goes straight to my breaker box. Now this is to keep any relays or automatic stuff from cooking my generator (if you backfeed your generator with shore power it's smoke time). I can plug into the outlet that comes from the generator, or one of the other 2 outlets from shore power. Either outlet is used for 220V and one is 110V one way and the other is 110V the other way so that if I only have 110V available I can switch my plug from one outlet to the other to get 110V to one bank of breakers or the other. Does that make sense? Think about it for a while. If you only have 110V available how are you going to use it where you need it? Make it so you can switch it from one side of breakers to the other, I use my shore 220V panel outlets to do that (you wire one up one way then switch the wires on the back to the other to make it the other way, my bus is wired 220V because my air cond is such and so are 50 amp hook ups at campgrounds or you can use 30A single. Also when you wire up your 110V outlets use a wire that is 4 conductor so you can have one of them hot when you only have 110v or both hot when you have 220V). I took a 12V battery charger and built it into my panel so I can charge my batteries while 110V or 220V is available. I can also flip a switch to charge them from the alternator while motoring down the road. I have house batteries in my engine battery compartment, 2 deep cycle 12V batteries which will get me by for a few of days. Also in my OCD panel I built in a small 700W inverter so if we need 110V power for any reason we can plug directly into that (it's not wired up to anything). Sometimes Joan likes to run a fan at night or charge a phone when we don't have 110 or 220V and don't want to start the generator. My new digital TV is 12V, my antenna amplifier is 12V, all my lights, range hood w fan and light, water pump, furnace, and what ever I can't remember all run on 12V. The only REAL reason I need high voltage is for my air cond or microwave and/or charge house batteries. My fridge is 3 way, propane, 12v and 110 volt so that is a no brainer. A 12V solar charger keeps you from having to use any high voltage at all unless it's hot and you want air cond. As far as the microwave goes we rarely use it and the stove will take the place of it 99% of the time. I think that's it. I suppose if I had bought a larger inverter then the microwave thing would not be a problem but I can't imagine using an inverter for air cond. Plugging in at a campground is always nice but we can be self sufficient for days at a time if need be. It's really nice while traveling, you can just pull over anywhere you want and use anything you want by using the generator and/or batteries. I hope this is understandable but if not ask questions and I will try and clarify my ideas. sportyrick

[Diesel Dan]

Thanks sportyrick. It'll take me a while to digest all that, but more importantly I'll pass on the info to my Electrical Engineer friend who will be helping me with the wiring. I'm not sure how much experience he has with all this 12v/120v/240v mixing and matching, but I'm sure with his electrical knowledge and the info I've gotten from this forum, we'll be good to go! I'm probably going to run the A/C, heat, fridge, TV, and a couple outlets off 120v, everything else 12v, and avoid 240v altogether. I may ultimately get a generator, but that will probably not happen during phase1 unless I stumble across a great deal. But I'll definitely start off with a bank of house batteries, charger, inverter, and isolator. I'd love to do solar, but need to do some more research...

[Diesel Dan]

Originally Posted by pjespers

12 Volts - fluoresent lights - small auto fans - tv/vcr - radio
120 Volts - A/C - dorm fridge - hot plates - toaster oven
2000 watt inverter/charger - 2@105 ampHr AGM batteries - 4@85watt solar panels
System also gets power from alternator via isolator
We mostly use the AC appliances when we have shore power. We do run the fridge all the time. Between the solar panels and the alternator, we have enough juice to keep it going. At night we plug into shore power anyway. We can run one of our A/C units while driving. Heat is provided by a wood burning stove or an 'oil type' electric heater if there's shore power.

Pjespers, I have a question for you:
While driving, are you able to run your air conditioner and fridge off 120v power that is being provided from your 12v battery bank and solar panels power being run through the inverter to make 120v power?

[Diesel Dan]

Hmmm... seems like I'm going to have to get a generator if I want to stay cool while driving during the day, and run my fridge. It's too bad diesel generators are so expensive, 'cause I could run it off my main fuel tank. But sadly, I think my budget, and practical ROI considerations force me to go with gasoline. I'd really like to limit the number of different fuels I have to carry - especially the highly inflammable ones. If I were going to be full-timing I'd consider diesel, but it wouldn't pay off for occasional camping trips.

[Redbear]

I'd really like to limit the number of different fuels I have to carry

What about propane? A lot of standby "spark ignited" gensets that sit for long periods of time use propane instead of gasolene. By "sit" I mean they don't regularly empty their tanks and get refilled with fresh fuel, whether they are "exercised" or not. Propane stored a long time does not turn to varnish like gasolene (messing up your carb) or get contaminated like diesel fuel that sits. If you are doing a propane stove, fridge, or water heater on the bus, you may want to look into a "spark ignited" genny with a propane kit. This is usually a new carb, plus a pressure regulator and electric fuel solenoid valve.

[Ob1]

My lighting set up swings either way, AC or DC. Each light fixture has 12vdc and 120vac wired to it independently. The fixtures have a switch for each type of circuit, feeding a bulb socket with the proper lamp inside.

Net effect, lights where I want them, when I want them regardless of power source. The only light that is 12vdc alone is the shower light. The wiring is there for a 120vac light, but until I find a fixture and switch that I feel is safe when wet...I'll stick with 12vdc, it doesnt tingle near as much!