Newbie with Coach Technical Questions

[BirdDog]

I'm looking to buy my first RV. I'v joined the RV Consumer group for it's critiques. I live in the Black Hills of SD. So it's hard for me to go to many RV shows easily. I need to depend on the internet for much info. I have some questions that may seem dumb. First I'll let you know what I'm interested in.

Definitely a class A motorhome. Looking at shorter. I want something that is good for travelling. Not so much something I park at a campground for weeks. I can see the attraction of something longer, like 33 foot range...I like some of those floor plans for living. My need, for now is for self contained for about three days stay. Might change my mind, but can only see that as a want for now. It is just me and my ever lovin' sweetheart who is also my bird dog. Now to questions...

Have they made generators quiet in general, now? I remember those noisy things that drive everyone crazy. I'm wondering if I have to worry about this? I know Honda makes some pretty quiet generators. If I want quiet, will I be forced to change out, or install a Honda? I know something made for the motorhome will work out better since it's designed for that use.

Am I wanting too much in wanting to be able to run an air conditioner much of the time while self contained? Remember, about a three day stay.

I'm thinking of using solar panels to help supply air conditioning. Actually, to help as much as possible with power. I figure an air conditioner will use about 1KW. I don't have much of an idea how much roof size will restrict me in solar panels? Also, if I go with as much solar as I can, I expect I'll have to increase the size of my inverter....This won't be any problem?

Other than that, I'm really interested in a coach that is nice to drive. I don't want to be going crazy trying to drive the Taj Mahal down the road. I also like the performance, and gas mileage that will come with the shorter coach. Don't know exactly what to expect. Just know it will be better. Am considering a 24', with Workhorse chassis, and 8.1L Vortec. Hopefully this has the Allison transmission. ... Real good?

I'd appreciate any thoughts....info....

Ron

 

[rbraucht]

Newbie with Coach Technical Questions

Can't help you with your choice of motorhomes. But I can tell you you won't run a decent size air conditioner off an inverter. you would need the mother of all inverters and a trailer to haul all the batteries in. :laugh:

 

[BirdDog]

Newbie with Coach Technical Questions

I appreciate your reply. Appreciate your concern. I'm just trying to help out the generator. Not necessarily take over. Wouldn't be any need for more batteries. I'd be using power from the panels when they are generating the most.
I've found plenty of decent size inverters in RV's. Nothing too special about the size of an inverter to supply from DC to run an AC. I don't know for sure, but am confident those AC units don't use more than 1KW. It depends on the size of the roof and size of the panels...I'm thinking it just might be possible to supply enough from solar to run one AC unit. Even then, if I just help out the generator, I'd be saving gas. Most generators aren't loaded down very much by the AC.

RonP

 

[Gary B]

Newbie with Coach Technical Questions

Hi BirdDog, you haven't done enough reseach on air conditioner units, they are electrical HOGS, the most effiecnt units require about 16 to 20 amps on startup and run near 8 to 12 amps. Any generator of less then 3000 watts has a very tuff time operating the typical roof air. The money you would spend on solar panels and batteires would buy enough gas to operate a 7000 watt onan for amny amny hours. A 7000 watt onan will burn approx 1/2 gal of gas per hour. Typically solar panels are 15 watt and cost more than $300.00 and you need batteries to store and use the 12 VDC and how much a 3000 watt continuios use inverter would cost is unkown to me, but not cheap. My guess is the new power cells their working on would be better. :laugh: :bleh: :approve:

 

[Jay Raymer]

Newbie with Coach Technical Questions

DC AIR makes solar powered AC units in 12, 24, and 48 amp ranges. They run up to 10,000 btu and work rather well from what I hear. I don't have any installed on my units but know someone that does and he says that they work just fine. They run off batteries (and not a truck load of them) and use the solar panels to recharge them.

 

[bassspud]

Newbie with Coach Technical Questions

Running an air conditioner off of an inverter isn't that bad.... You’ll need an inverter in the 3000 watt advertised range. Xantrex makes alot of good choices. I recommend the X-power series. Actually Xantrex makes alot of other companies and other labeled inverters as well (statpower,Whistler,etc...)The whistelers are actually xantrex portawatz series inverters. I have installed and used the portawatz 1750, and the x-power 1200 plus. Both work quite well. I have run an air conditioner off of the 1750, but I recommend using a 3000 watt model.

RV rooftops (Coleman etc.) typically use between 1050 watts and 1800 watts to run. The startup current is much higher approaching and even briefly crossing 2400 watts. Yes I realize that all of our RV's have 20A breakers on the AC, but since the onrush current is only for a brief amount of time, it won't actually trip the breaker.... usually!

In my 27ft motor home (1 AC unit) during the day on a hot day my compressor on the AC runs 70-80% of the time. Most RV's aren't well insulated :angry: .


Here's the bad part!

You'll loose 10% of your power off the top in the inverter.

Photovoltaic panels cost about $3.20 per watt if you shop around. If your AC uses something in the middle of the range (1400 watts) then your panels will cost almost $4500! The panels will cover 4ft X 31.5 ft. You'll need some large batteries to handle onrush currents etc, and if you and to run things in the evening when there isn't full sunlight. That 1400 watt AC unit will be pulling 129A off of the batteries. In other words, it will take 2 standard (type 34) batteries per hour to run the compressor. Realize that at night, the duty cycle of your AC unit is much lower 20-40% depending on the insulation, and how much of the coach you're cooling. That helps a lot! At 20% duty cycle, your 2 batteries would last 5 hours instead of one. Also factor in that your compressor uses alot less power when the condenser side is cooler (at night) then when it's hotter (the spec you'll find for your air conditioner) Things become a lot more feasable.

The system MUST be installed by somebody that really knows what they are doing, is really good with electrical math, and understands solar power. Can fabricate everything, and has the shop and tools to do it. For example. Since we're running 12V DC at currents well over 100A, your cable lengths must be SHORT (no more then a few feet from the batteries to the inverter), and MASSIVE I'm running double 4AWG if memory serves to power my 1200W inverter. Properly fused (I used 200A breakers designed for car audio). You'll need a charge controller to make sure you don't overcharge you’re batteries. The wire from the panels to the charge controller then the batteries must be huge as well. If it's exposed to sunlight, it must be sunlight resistant. The battery racks and panel mounts should be custom welded.

Not counting labor, to do something like this here's what it costs:
photovoltaic solar panels $4500
Inverter $450
Charge Controller, probably have to be custom built, I've never seen a 120A charge controller! $6-700
Total: Not including batteries, wire, relays, labor etc..$5600

But it sure would be nice!!!! You could leave the inverter on all the time! Just use the microwave, TV, AC, whatever you want whenever you want...just like at home!

If you have more questions, drop me a line.

bassspud@yahoo.com

 

[hertig]

Newbie with Coach Technical Questions

No, generators are not particularly quiet, with the possible exception of the Honda EU series, but these are not built-in RV generators. I think all RV built-in generators are fairly noisy and use the insulation of the generator compartment for whatever quietness they achieve.

Unless those 'solar' air conditioners mentioned above are any good, you will probably not be able to (practically) power air conditioning with anything other than plugging into an outlet or running a generator. And if you are running a generator, there is no point in trying to 'help it out' with solar.

 

[hertig]

Newbie with Coach Technical Questions

Also, if you are looking for something to drive from one point to another, staying overnight on the way, and not stay in for days at a time, you might want to consider a class B (van) motorhome. Class A's are nice, but they get lousy gas mileage and don't 'fit' everywhere. A class B is just a big van, easier to park, store, and fit in tight locations.

With their 'pop-top', Sportsmobile overcomes some of the 'cramp' factor of class Bs, and they allow you to design your own floor plan in the brand of van you prefer.