DC or AC power?

[Locutus]

Okay, so I'm contemplating how to do the electrical service for lighting and appliances in my yet-to-be-purchased bus. Some of the things I need to consider is whether to provide a 30 or 50 amp service, whether to purchase household or RV appliances, whether to supplement with solar, whether to add a genset and what power rating, and whether to wire for DC, AC or a combination.

The larger and more packed with appliances the bus will be, of course the more power hungry. Some of the appliances will only be used intermittently (microwave, washer/dryer, etc.). Others will cycle constantly (air conditioning in the Summer, and refrigerator). So I have to consider peak loads and average loads.

Right now I'm thinking of ways I might try to make a 30 amp service adequate, even with lots of stuff in the rig. I'd also like to keep the wiring as simple as possible, so I'm thinking all DC or all AC, not a combination. Cost is also a consideration.

So I'm wondering: How practical would it be to run a 30 amp AC shore power service (plus perhaps a supplemental genset and/or solar) solely to keep a rather large battery bank charged, while running battery power through an inverter or multiple inverters to power everything in the rig? On the plus side, I see this as a relatively simple power solution in which less expensive household appliances can be used. A large enough battery pack should be able to handle peak current draw while the charger compensates with a level load on shore power closer to 30 amps. On the downside is the fact that constant use of the (expensive!) battery pack may shorten it's useful life, and also the cost of the inverter(s). Peak current draw can be mitigated somewhat with switches that redirect power from one appliance circuit to another, so as to prevent overload.

I would like to be able to boondock for extensive periods of at least one week without having to run the main engine, hook up to shore power or refuel the propane or gasoline (for genset).

Appliances I'm considering are:
Apartment sized 110 VAC fridge/freezer.
Compact 110 VAC washer and dryer. (perhaps propane heat for the dryer.)
Microwave, 1000W, 110 VAC
One or two air conditioners, 110 VAC
Propane range
Propane water heater
Propane central ducted furnace
Gasoline or diesel genset
Stereo system
At least one flat panel (LCD or LED) TV.
Fluorescent and/or LED lighting.

Any feedback is appreciated!

[NewSkewlHauler]

I am going with mostly DC power because we'll be traveling a lot. Free power from the alternator! The only things we intend to run on AC would be the air conditioning, microwave, and fridge. It just so happens that our fridge is a 3 way rv model. For the times we're on shore or genny power a converter will supply our needs.

We'll have a combination of power sources because of how we're going to use ours. You might do well with AC only depending on usage. Smitty did that with his. I'm sure he'll comment soon. He is intending to boondock and be mainly sedentary...I think.

Good luck. Hope I've helped!

Ben.

[lornaschinske]

Originally Posted by Locutus

... Right now I'm thinking of ways I might try to make a 30 amp service adequate...
Appliances I'm considering are:
Apartment sized 110 VAC fridge/freezer.
Microwave, 1000W, 110 VAC
Propane water heater
Propane central ducted furnace
Stereo system
At least one flat panel (LCD or LED) TV.
Fluorescent and/or LED lighting.

You should have no problem running those off of a 30 amp service. If you are going to stay in campgrounds at all, I would suggest you get an AC/LP water heater. For long term usage, even paying per kwh, it is cheaper to run your water heater off electric than LP. But you would need to run an LP vs AC calculator to decide that one (I set up an Open Office Spreadsheet for my use but it's just Cost of Propane per gal divided by 22 to find out what the "kwh" rate would be... if propane's kwh rate is lower than what the park charges for AC, run propane... if higher than the park charges for AC, then run heater on AC). We just really like the option of doing that. You need a mix on your lighting... some 12vDC and some 110vAC unless you want the expense of doing all 12vdc (don't get cheap DC flourescents... I've burned up 5 cheapies with one "browning" the ceiling). Overall 12vDC lighting with 110vAC "task" lighting (like under cabinet mount AC flourescent lights... if dual tube, try to get them to where you can turn on one tube at a time but you probably won't really need two tubes) is what you need.

Compact 110 VAC washer and dryer. (perhaps propane heat for the dryer.)
One or two air conditioners, 110 VAC

You will want propane for your dryer (it drys better)... a 110vAC dryer will only have one heating element so it will take longer to dry clothes. To run two AC units, you will either need a thingy that will cycle the two AC units so they do not cycle on at the same time or you will need a 50 amp service. And a big Genset. 3K genset is the absolute slap dad minium that you will need (does not count towards AC dryer and that's using 1 Air)

You will need to have a huge battery bank (I don't think you will have enough room even if you had a motorcoach) to run entirely off batteries. Use a solar worksheet to size your battery bank. You can find them all over the internet. Then start tweaking your loads. Why do you need two AC units? Duct your AC to maximize your cooling... boost with a small fan mounted in the ductwork if needed.

[bus-bro]

You could wire for a 50 amp service. Not all that much more money, and easy to adapt down to 30 or 20 or 15 amp power. The trick is to wire only for 120 volt loads, so your maximum power is two 120V 50amp feeds. You can then connect your 240V wires together to one input (the red or black wire) to feed your panel with 120V 30 amp.