Solar Powered RV

actually the answer for a mobile application, is Not Solar,
it does make use of a large bsttery bank and either low draw re-configured/package
5000btu a/c for the bed room, or a low draw 'heat pump'
and a quiet generator for 'Daily' recharge

Almot wrote:
Smaller A/C that draws 45A at 120V, is still 50-55A from the battery, considering inverter losses. While it is possible to run that much current direct from solar, direct connection is not going to work to cool down a bedroom in the night - obviously. There is no sun in the night. With Peukert effect this means 500 AH or more, overnight, from the battery bank. Which means - you must have at least 1000 Ah bank.

Another problem is - how big a MH should it be, to accommodate a panel big enough to put 500 AH into a battery in daytime, plus another 500 AH to run the A/C in daytime, plus another 100 AH for all other items. Total 1,100 AH daily over 24 hours - so the panel must collect 1,100 AH over 5 or 6 hours of full sun. This is roughly 5,000W array. About 7ft wide and 50ft long, ouch....

The bottom line is, OP - forget about A/C. At the very best you would be able to run it (with solar) for a couple of hours.

Hi mena,

I'm not concerned about the size--but all reviews on the aims are POOR and that is being generous.

That is a shock. Well at least we know that inverter can put up with some really good loads. PT, I know that's more than you need but it's a big 12V inverter. It comes with a wireless remote!

Hi folks,

I wrote the Etrek folks to ask which inverter. Imagine my surprize that it is the 5000 watt Aims. 5000 watt PSW Aims

MNtundraRet wrote:
pnichols:

Thanks for the info.

However; reality is not quite here yet. Still many problems with larger lithium batteries "safety wise", controlling thermal runaway, etc.

It would be nice to hear from an owner of one of these vehicles after they have had time to use it under "real world" conditions. Too much "hype" early on from some of these manufactures. A year or two of use from real customers brings out the flaws. Boeing airliner is a good example.

IMO, 20 minutes is pure crap. If they take that 800Ah LI bank down to 80% DOD then charge that means they'd need a 1920A charger!

I need to address some misinformation. There's different chemistries of LI. Not one kind. The one's used in boats and RV's are NOT the same one's used in the 787, mainstream EV's, laptops, and phones. The lesser LI batts are MUCH less energy dense and not as volatile and are proven and safe. If you're interested in their capabilities visit the DIY EV forum and some of the sailing forums.

Hi,

(edit they say 1600 amp-hours--but I think they mean at six volts, which is "cheating" a bit)

I see they are using 8 six volt AGM batteries totaling 800 amp-hours of storage. They don't mention system voltage. They mention 9 to 15 hours of run time for the air conditioner (11000 btu's). Assuming 50% use cycle 15 hours = 7.5 hours of run time.

They claim a recharge time using the vehicle engine of 2 hours. It does 3500 watts at idle, and 5500 watts at highway speeds. I think it is safe to assume the 2 hour time frame is for highway speeds. That implies 11000 watts going into the battery? (less 10%).

So the air conditioner may draw about 1200 watts based on the 11000 btu's?

I see they use a 5000 watt inverter. Anyone notice the make and model?

pnichols:

Thanks for the info.

However; reality is not quite here yet. Still many problems with larger lithium batteries "safety wise", controlling thermal runaway, etc.

It would be nice to hear from an owner of one of these vehicles after they have had time to use it under "real world" conditions. Too much "hype" early on from some of these manufactures. A year or two of use from real customers brings out the flaws. Boeing airliner is a good example.

MNtundraRet wrote:
The Class B information came from an early replier claiming a Class B manufacturer had an electric option model that could run the air-conditioner for 8 hours, and recharge the battery-bank in 20 minutes.

That's where I came in asking for a link to check his claim.

Mark,

I'm not sure your inquiry above ever got answered to your satisfaction.

Roadtrek calls their E-Trek a "Class B" all electric RV. Here they claim testing shows running of the air conditioner for 9 to 15 hours (select the "E-trek Operation FAQs"):

http://www.roadtrek.com/faq.aspx

Here this author (scroll down to the section titled "Fast and Efficient Charging") claims that lithium ion batteries can be recharged in as little time as 20 minutes:

http://www.technomadia.com/2011/10/lithium-update-2-the-promise-of-lithium-rv-batteries/

mlts22 wrote:

qtla9111 wrote:
I don't think it is so much the class of the motorhome but for people to know that there are advances in technology. Whenever a thread starts about solar and A/C it is poo-pooed from the start by many people who are just not in the know.

Solar and batteries have come a long way. I know of three people who power their rvs A/C with batteries and solar but they refuse to post here because they always get shot down.

As someone else said, how about looking for an alternative by using a smaller unit with a smaller draw that will keep you cool in your bedroom at night.

These threads always go bad, they don't need to. Be more open-minded and accept the fact that the world doesn't have to exist solely on 110 and fossil fuel. A big mistake was made over 100 years ago when they refused Tesla's proposal.

There is a Youtube video maker whom I follow, who is running a small (5000 BTU) A/C off of a few solar panels. It isn't the best setup, but it allows him to run the A/C to help cool/dry the air for a couple hours in the evening.

Eventually we will get to a point of being able to run an A/C off a larger rig's solar panels. It will take some inventions such as a slide-out mechanism for more square footage for panels to use, better charge controllers (perhaps each individual cell in a panel would have a small regulator, which would cause the energy loss from shade to be as low as possible), better batteries (supercaps, lithium/air), and maybe even advances in wiring. A superconducting wire the thickness of a thread would replace a pretty thick wire, if room temperature superconductivity can be achieved with a ductile material.

There are some cool innovations coming out now. I forgot the brand, but a hybrid converter/inverter (Victron has these as well, but I forgot the brand that just came out) which allows something like an A/C or microwave to run off a generator, but the inrush current be handled by both the generator as well as the inverter for a brief time, then the generator handles the load.

I've seen that video too. Some cool stuff going on out there. Just a matter of experimenting as well as new technology. Batteries are getting better.

Almot wrote:
there comes a generator.

IMO, there's no getting around some kind of fuel powered energy source for most people. I live in the desert and we have 360 plus days of sun per year. The only place we would go boondocking where I would need A/C is out in the desert. No where else is hot enough. The only application of this that I would interested in is running A/C from inverter on the way to a CG to save some fuel. It would be neat to power the A/C from solar for about 3 hrs and arrive at the CG with a nearly full or full battery bank. The thing is it would be WAY cheaper to buy a big honkin marine alternator with a remote bridge rectifier and power the inverter from that.