# Concieve the electric RV



## This is Bill (Oct 27, 2008)

The electric RV.

Instead of buying a $75,000 -$100,000 brand new RV, what if I bought a used one for $10,000 as a conversion project? The technology has changed very little on the inside so it can be a few years old as long as it is clean and in working order (fridge, sofa/bed, tv, generator, toilet/bath, carpets, etc.).

I don't like driving all day long, so traveling 200 miles at 55mph in one day is great. Besides this leaves more time for camp set up. Some mountain grades can be very steep so the ability to go at least 5% grade at times is a must.

What motor/controller/battery set up will work? Some cities use electric buses so I know its possible to find some heavy duty parts.

Hmmm. Imagine removing the primary ICE and transmission. Could a powerful ac motor(s) be attached straight to the drive shaft and still meet the torque and rpm requirements? Perhaps a gear ruduction assembly would be required. Perhaps a change in the ratio in the diff would be needed.

The existing generator will be left as is to assist in its normal functions (air conditioning, and other ac power) but it will also be able to help slow the main battery packs from depleting. Obviously it would require a much larger generator to keep the batteries from ever depleting but the goal would be to assist in the range bump it from lets say 100 miles electric only to 200 miles using generator. Re-gen braking would be used on all the grade decents and braking during traffic. Obviously this is a minimal amount but every bit helps for range extension.

The long flat roof is ideal for solar panels. If my RV is sitting out doors all the time, then it makes sense to have solar panels. The extra weight and cost is a draw back at first, but the savings over time (and thats what solar is all about) would be great. 99% of the time an RV is sitting around at your storage lot or your house or even the camp ground. I would love to have the sun recharge the batteries for me, sort of like a full tank of gas a week, only not paying $250 and worrying if the gas is getting old as the RV sits through winter. And if my RV is parked in my side yard, then perhaps it's solar energy can be fed back to the utility company's grid, another cost savings plus over time.

When I get to the camp site and pay my $25, I could re-charge the batteries...big gas savings especially the more I use the RV over the years.

Another savings could be the yearly registration. Maybe there is a loop hole for a electric RV and could save hundreds each year.

Most RVs are desinged for their weight and also to pull something like another car or boat. Plenty of room along the frame for all of those batteries. Even if some of the storage compartments have to be sacraficed for batteries that would be just fine. I think lead batteries would be much cheaper at first, but then when you consider that the generator had to be used most of the time during operation, and too much increased weight, in the long run it would be worth while to have higher energy density batteries right from the get go. 



Or just not mess with and have a regular motor home with it's factory warrenties and shell out $2000 for gas each trip. Plus all the maint cost.

I've read a lot of these posts and a I'm interested in how this concept can be improved. Good day.


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## TX_Dj (Jul 25, 2008)

I'm not saying it's impossible, but fairly improbable to meet your goals.

The Top-Two killers of EV range are weight and drag, something an RV has in abundance.

If it were purpose built from lightweight aluminum and composite materials with a focus on ultra-lightweight materials and the bulk of the vehicle weight made up from lithium batteries, it may be possible to get 200 miles range out of it for $300k+ in EV and vehicle construction costs alone (i.e. a "shell" with nothing inside.)

If someone can make an ERV for a reasonable price, I'll be interested. I've thought for years that considering you can get 50 amp service at most RV parks, it would be simple to roll up, plug in, and recharge while you're camped.

However, an ERV would be really rough to go boondocking, which is my favorite sort of RVing.


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## ElectriCar (Jun 15, 2008)

It's way cheaper to buy electricity than do it with solar cells. It'll take longer than you'll live to pay for them likely at todays prices. Wait for Nano Solar's products to hit the market at 1/10 today's cost and you'll be much better off. I think you'll be able to buy them in a year or so. I can't wait!

And wanting an RV to go 100 miles without a recharge is going to be REALLY expensive, a lithium pack surely!

But you never know the answers until you investigate your ideas. Some work out and some don't. Those never attempted never make it!


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## This is Bill (Oct 27, 2008)

Thank you for the responses. Since the closest vechicle to a RV is a bus, I did a search on hybrid buses, and this company illustrates the feasability. Thought it was interesting so I posted it here.

http://www.advancedenergy.org/corporate/initiatives/heb/hybrid_tech.php

And I agree that the use of nano solar is ideal, it's so thin that you wouldn't even know that they were up on the roof unless you climbed up the ladder. I wonder if it could be somehow fashioned on the awning for increased solar surface area.

--Bill


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## mattW (Sep 14, 2007)

I certainly don't think it would be impossible. In fact I think it is a pretty good idea. With the combination of a generator, solar panels, a slowish top speed and a huge battery capacity you could certainly get a decent range. If you could go 100 miles then stop for an hour or two for lunch (with the generator and panels going) then drive the other 100 then it would probably be a lot easier/cheaper. What sort of HP do RV's have and what sort of budget do you have for the conversion?


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## rfengineers (Jun 2, 2008)

Just a thought experiment here:

My RV gets about 8-mpg. Using the VERY ROUGH model for EV mileage (36.6kWhr/gal-of-gasoline and about 25% efficiency) my RV should consume about 1150Whr-per-mile. For a 100-mile range at relatively low speed that would require about 140kWhr (to 80% dod). If I ran my 6kW generator and drove 50mph that would knock 10 or 12 kWhr off of the battery requirement.

Based on this, my GUESTIMATE for my RV would be a 100 to 150kWhr battery.

Using 225-AHr 6-Volt lead batteries (e.g. Trojan T105), that would be about 94 units (126,900Whr) for a weight load of about 5734-lbs.

Now, how long would it take you to recharge assuming you had 120-Volt 50-Amp service at a campground? And how long would it take to check and top-off the batteries!?

It is certainly feasible, but is it worth doing?

Joe


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## This is Bill (Oct 27, 2008)

I like your GUESS ESTIMATE example!

I agree that using Lead batteries just isn't a good idea. This drives the build cost way up. Its easier to get a loan for a new RV, vs an unsecured loan to do this project. 

A lot of gas RV's use Ford Trition V-10 which I think is around 300hp 360ft/lb of torque. That's an incredible amount of hp to match with an electric motor... probablly 700 volt or more system would be required. Expensive and dangerous. 

Its ok if the charge time takes a long time, say 14 hours. If I roll into the campsite at 6 pm and leave at 8 am the next day, that isn't really interfering with travel time.


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## TX_Dj (Jul 25, 2008)

I think a 144v system can produce far more than 360 ft/lbs torque. Heck, Crazyhorse makes over 1200 ft-lbs, and I think it's a 300-ish volt system (with gobs and gobs of amps). However, 300 HP = 223 kW... which can be generated by 111 volts @ 2000 amps... or 223 volts at 1000 amps, or 446 volts at 500 amps...

The problem isn't making the power so much as finding something that can handle that power...

Additionally... that 300 horsepower V10 probably only needs about 60-80 HP to push that RV down the road at freeway speeds. Sounds like a job for a large AC drive to me, something, oh, I dunno, in the 440 volt RMS range?

It's do-able... but how much would you want to spend? If you buy a nice RV for 100k, and put 400k into the drive/battery/charger systems, who would you ever resell it to when you no longer need it?


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## LeTank (Jun 24, 2008)

Pretty cool idea. I would use the nice tractor (commerical) 12 volt 800amp lead acid batteries myself for starters. I use them to run part of my house with my solar system and they are great. Can get them at Napa for $189.00 and they have a 72 month replacement warrantee. Worth checking out. Each weighs about 75-80 pounds. 

I would love to see an EVRV on the road.


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## LeTank (Jun 24, 2008)

TX_Dj said:


> I think a 144v system can produce far more than 360 ft/lbs torque. Heck, Crazyhorse makes over 1200 ft-lbs, and I think it's a 300-ish volt system (with gobs and gobs of amps). However, 300 HP = 223 kW... which can be generated by 111 volts @ 2000 amps... or 223 volts at 1000 amps, or 446 volts at 500 amps...


Actually, I found a 3 phase 150hp AC motor a few years ago through a Canadian electric motor company for $1,000 new. I think a 150 hp motor would easily run an RV down the road. It was rated at 3650 rpm. 
I can't remember the name of the company since it was a while ago, but you could probably dig around and find something similar.

I believe its possible without spending a life savings on it.


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## This is Bill (Oct 27, 2008)

Correct me if I'm wrong, but if a high volt system is used than I won't need as thick gauge wire. 
Sort of like why the power company uses high voltage to transmit power because the resistance is so great. But what are the other inherent drawbacks from using highvolt/low amp system compared to low volt/high amp?

If I use a really high torque rated motor than I think that would require at least a four speed transmission and I would have to shift a lot just to get going, but when it comes to hills all the torque will be there! 

I hope it is possible to not use a transmission. I think that goal really determines what type of volt/amp ratio and motor required.


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## mattW (Sep 14, 2007)

So do you have a ballpark budget? If you are serious about it we can put together something on paper. It would be an awesome project.

Higher than about 156V generally means you need to go AC, (or twin motors) which is more expensive. But you probably should anyway. Higher voltage means less energy lost as heat in your cables and batteries, we just need to find you a system that will let you run that high. It would also probably be worth getting a professional electrician to help at the higher (more dangerous) voltages.


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## Qer (May 7, 2008)

This is Bill said:


> But what are the other inherent drawbacks from using highvolt/low amp system compared to low volt/high amp?


Cost. The higher the voltage, the harder to build a controller that can handle it. Zilla 1k, for example, came in a "low" voltage flavour (I think it was up to 200 Volt) and a high voltage flavour (375 Volt) and the price tag was noticeably more painful on the HV-version.


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## 280z1975 (Oct 2, 2008)

Some thoughts (though I have never converted) ....

1) Go AC, as the higher voltage can work. Look into the systems used by city buses, as you have already, as they can handle the weight and torque.

2) Life4Po are just about the only choice of batteries for weight and capacity. This will be your biggest cost.

3) Your choice of RV is going to be a HUGE decision. I suggest you go with the lightest weight one you can find (and as aerodynamic as possible). Then go inside and gut as much out of it as you possibly can. After that start to work on the outside and adapt it's look and design to smooth the flow of air. These changes will make you "free" miles off your battery pack.

4) Think of the use of solar (and also wind) as an assist for the charging or a bonus, but their cost won't pay for itself for a many years, but if you want the independence and have the cash, they can help.

5) With the investment of such a great amount of battery power, you could take your house off the grid and run it off solar and wind using your RV battery pack as the power reserve. Far out thought, but interesting idea. 

6) Look into the idea of having the RV system simalr to the Chevy Volt, where you have some generators help or make all the power needed to run the car. It will give you more range. Make it biodiesel and you can just pull into the local truck stop, ask for the old cooking oil, spend the afternoon converting it and bam, you have your day to go.

An interesting engine I came across when watching Mythbusters the other day was this aircraft engine.
http://www.rotax-aircraft-engines.com/a_engine_582.htm
It can produce up to 48kw of energy and weights only around 90lbs! now that is some power to weight ... they were using it for a personal hovercraft idea, so it's got the ablity to put out the power, but finding the fuel for it might be a problem. It won't get you all the power you need, but it can get you farther(or emergency power).

7)Look to the boating industry (and airplane) for ideas of how to make the RV more self-sufficient, efficient and lighter

8) Be prepared to have two important things, time and money. If you have these ANYTHING of this sort is possible. If you get this right consider turning this into a commercial enterprise. The tax credit for battery packs would make a 140kw pack a large discount on the cost...

I wish you all the best ...


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## heynow999 (Mar 2, 2008)

I think it is a great idea. I can imagine you can get old RV's dirt cheap with the slow economy and the fear of gas prices rising again.

I have a 92 Isuzu Trek A-class RV. It has a small 4 cyl diesel and gets a solid 15 mpg. It is probably about 110HP.

Really how much would it cost? Find an RV with a blown motor-under $10K. Maybe 80 t-105's - $10K, Motor for $1k. The electronics, no idea? $5k? Scrounge for parts, find used stuff.

I too think the panels are probably a waste. It is a good idea, but it would probably not be cost effective. You could probably fit 8 x 200 watt panels on the roof of a typical A class. The best you can get in the US is about 6 sun hours a day so that would make (8x200=1.6kwx6hrs)=9.6 Kwhr. If we use the previous estimate of 1150whr/mile, those panels would give it 8.3 miles of charge everyday. This is under good conditions, not taking any losses into account. Those panels would cost about $5K, then a charge controller $1k, then installation. 

Actually, I guess the key to making the panels practical is using them as much as possible. As was suggested, using them to run your house would be a good idea. You can do net metering in most parts of North America these days.


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## ItsMe (Mar 17, 2009)

I had this same idea, especially the charge from the campground J
You have gotten some good responses.
Some of the numbers here don’t look good for us.
I was looking at the electric busses too.
How about a parallel system that can just use the electric to keep you going once up to speed as someone mentioned.
I wonder what that would take?
Also, have you seen the latest on Lithium batteries that they came up with a way to charge in minutes?


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## eao (Mar 6, 2009)

Look at the AC Propulsion system. 360 volts, 200 hp peak, maybe not enough for an RV? Depending on weight, etc., I suppose.


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## Harold in CR (Sep 8, 2008)

I remember seeing RV's on the road, that had the long "Snout? front end on them, similar to the Ford Windstar van. Might be somewhat aerodynamic ??? Should be a 1 ton frame, so, not a gigantic unit to push air with ???


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## Gardoglee (Jun 2, 2009)

OK, the idea of the electric RV appeals to me as I just purchased an RV, and converting it to electric is interesting. One advantage I have is that, as an earlier poster suggested, this particular RV has a very lightweight aluminum frame (1990 Holiday Rambler Aluma Lite XL 31') which makes it significantly lighter than some other units of comparable age, price and size.

It is currently equipped with a GM 454cid V8 and three speed automatic. I currently own some bateries I was expecting to install as additional coach batteries, but I doubt they would be anywhere near adequate for this purpose (25 pieces Hawker SBS60 12v 50ah).

The original intent was to put solar on the roof and use the extra batteries with a large capacity inverter (5000-8000 watt) to run some 120vac appliances/computers inside, but converting the primary drive seems more interesting. How would one begin to aproach this?


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## piotrsko (Dec 9, 2007)

start with current MPG rating which can back into HP/ BTU per mile which can back into KW per mile.

since you now know what the energy requirements are to run it 1 mile, then figure out how far you need to go in a day at say 80% battery capacity.

now look at motors that will work and related controllers.

have fun


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## Moreforles (Aug 20, 2009)

TX_Dj said:


> It's do-able... but how much would you want to spend? If you buy a nice RV for 100k, and put 400k into the drive/battery/charger systems, who would you ever resell it to when you no longer need it?


Right now with fuel costs and the economy the way it is..... it's easy to find some very nice rv's for around 10k..... and some not so nice ones that need a little more work for a lot less


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## Moreforles (Aug 20, 2009)

This is Bill said:


> The electric RV.
> 
> Instead of buying a $75,000 -$100,000 brand new RV, what if I bought a used one for $10,000 as a conversion project? The technology has changed very little on the inside so it can be a few years old as long as it is clean and in working order (fridge, sofa/bed, tv, generator, toilet/bath, carpets, etc.).
> 
> ...


* Most or all of what you describe can be found in a smaller package (Class B) Used for around 10K (or less, if you start out looking for one with blown motor..... but rest of RV, clean and in working order.. with bed, fridge, microwave, generator ect........ A nice Class B with a slide or two can be very comfortable, large enough roof for some solar panels (I thought I heard of a printable solar Ink some time back, that would be great on awnings and such..... supposedly generated more power than conventional panels as well)

I was thinking along those lines - small Class B ERV or at the very least conventional Class B with electric upgrade.... trailer towed behind with small electric vehicle or scooter or both along with some or all of batteries and or generator and or more solar panels.... (wind turbine would be a must too, so batteries could be charged quietly at night while I was sleeping, when power hook up wasn't available and I didn't want to or couldn't run generator....)


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## samborambo (Aug 27, 2008)

This is a really interesting thread. One day maybe I might tackle something like an electric RV. 

A 40 seater bus uses about 100hp at 60mph cruising so you're looking for an industrial induction motor of about the same continuous rating. Buses actually have a very low coefficient of (wind) drag from its long narrow shape which is a good thing. However, when you multiply that by the 10m2 frontal area and also factor the 9 ton weight and higher rolling resistance compared to a car, the energy required would be around 260kWh for 180mi range at 55mph. You were pretty much spot on with the energy per mile at 55mph of 1120Wh/mi.

A little ambitious? Well, you're converting a luxury motorhome. You're probably going to spend US$50k on refitting on top of the US$90k for batteries.


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## OCRVGUY (Dec 12, 2009)

How about if you only needed enough batteries to run a compressor and the rest of the electrical devices in the Electrically propelled RV? Instead of batteries providing the power for the drive train, use a generator that runs off compressed air to power the electric drive system. It would be similar to a turbine generator but instead of jet fuel burning through it, compressed air would be forced through it.

The electric compressor i mentioned would run and fill at least three tanks that the generator would syphon it's air supply from. I say three so you have a reserve tank but two might be sufficient if space became an issue.

This solves some of the weight issue with the batteries as the tanks can be carbon fiber and the generator could be very lightweight also, depending on the materials needed and the size requirement to generate enough kwh's.

If you doubt the compressed air generator is feasible, then look at this link: http://www.mdi.lu/english/

This is a car company that make a compressed air engine for a passenger car. Surely I could even connect an ac motor to the drive shaft and get enough electricity off that motor. Be cooler with a compressed air turbine though


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## Overlander23 (Jun 15, 2009)

So, you're proposing using the electricity that is stored in batteries to run an air compressor, to run a turbine, to generate electricity for the motor?

Errr, why not just use the electricity in the batteries? Converting one form of energy to another always incurs a loss due to inefficiencies. Converting electricity, to air, to electricity is a phenomenal waste of energy. You'll never get more electricity out of the compressed air driven generator than you put in to create the compressed air... by a long shot.

Maybe I'm just confused here...


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## OCRVGUY (Dec 12, 2009)

Actually, the power is stored in the air tanks. I know I didn't explain it well but let me try another way.

The original problem was to go 200 miles in a day. If you carry enough tanks on board to run the generator to allow you to travel the 200 miles, then you only need the compressor to refill the tanks at the end of the trip. The batteries are to use the on board electrical devices and the compressor is for refilling the tanks. You can recharge the batteries and refill the tanks when you plug in.

if you want to go further than two hundred miles, then run the compressor off the batteries to re-fill the tanks. Couple this with some quality solar panels and maybe even extend range even further.


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## icec0o1 (Sep 3, 2009)

compressed air doesn't have that good of an energy density. You'd need HUGE tanks to propel an RV 200 miles, pretty much the tanks would the the size of the RV. Further, compressing air is not very efficient of a process. I would venture a guess that, for the very high compression required (1000psi) the efficiency would be in the 50%. 

So we're burning gas or coal with about 80% efficiency to get electricity that you'd use to compress air and lose 50% more of that energy. Further, air drive trains aren't the most efficient so say 80% and you get to something like 30% of the energy stored in natural gas/coal is used for propulsion. You might as well buy a 35mpg ICE which will do 25-30% efficiency in burning fossil fuels. 

The reason batteries are the standart storage medium is because they are 95%+ efficient in storing and releasing energy. Moreover, electric motors can also be in the 90%+ efficiency and there are far less moving parts.


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## Guest (Dec 12, 2009)

Three words for air. Don't go there.


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## ga2500ev (Apr 20, 2008)

Overlander23 said:


> So, you're proposing using the electricity that is stored in batteries to run an air compressor, to run a turbine, to generate electricity for the motor?


That is the proposal.


> Errr, why not just use the electricity in the batteries? Converting one form of energy to another always incurs a loss due to inefficiencies. Converting electricity, to air, to electricity is a phenomenal waste of energy. You'll never get more electricity out of the compressed air driven generator than you put in to create the compressed air... by a long shot.
> 
> Maybe I'm just confused here...


No confusion. OCRVGUY was trying to get around issue of having either tons or a mint's worth of batteries in the vehicle. The problem is that the energy density of compressed air makes it just as impractical.

A more realistic possibility is liquid nitrogen. It has the same profile as compressed air, but the phase change to liquid and back can store much more energy than compressed air. Also storage does not require pressurized tanks.

The energy density is still bad. As outlined here:

http://en.wikipedia.org/wiki/Liquid_nitrogen_vehicle#Energy_density_of_liquid_nitrogen



> *Energy density of liquid nitrogen*
> 
> Any process that relies on a phase-change of a substance will have much lower energy densities than processes involving a chemical reaction in a substance, which in turn have lower energy densities than nuclear reactions. Liquid nitrogen as an energy store has a low energy density. Liquid hydrocarbon fuels by comparison have a high energy density. A high energy density makes the logistics of transport and storage more convenient. Convenience is an important factor in consumer acceptance. The convenient storage of petroleum fuels combined with its low cost has led to an unrivaled success. In addition, a petroleum fuel is a primary energy source, not just an energy storage and transport medium.
> The energy density — derived from nitrogen's isobaric heat of vaporization and specific heat in gaseous state — that can be realised from liquid nitrogen at atmospheric pressure and zero degrees Celsius ambient temperature is about 97 watt-hours per kilogram (W-hr/kg). This compares with about 3,000 W-hr/kg for a gasoline combustion engine running at 28% thermal efficiency, 30 times the density of liquid nitrogen used at the Carnot efficiency [2].
> For an isothermal expansion engine to have a range comparable to an internal combustion engine, an 350-litre (92 US gal) insulated onboard storage vessel is required


The bottom line is that a 100 gallon non pressurized tank would be more doable than 50 highly compressed air canisters.


As for the efficiency, it's less of an issue than normal. The OP pointed out that they get "free" access to a 120V 50A outlet for their slip when they pay the $25 to park the RV for the night in the RV park. So essentially they can pull 6 kWh worth of power for however many hours they are there.


So it remains an issue of carrying that energy in a portable fashion. While batteries are efficient, there is a large weight/cost burden to be paid to carry them. Though the liquid nitrogen route is much less efficient it does offer the possibility of generating the range required without weighing a ton or costing a mint.


The other hidden advantage to liquid nitrogen is that in a lot of places you can buy it off the shelf very very cheaply. A log of airgas companies have liquid nitrogen as a byproduct of liquid oxygen generation. In some places it would be possible to fill that 100 gallon LN2 tank for as little as $20.


So it offers quite a bit of flexibility. You can get LN2 from outside sources. You can use your own distiller to produce it yourself just add electricity.


Finally the energy density listed is only to 0 degrees Celcius. Warming the LN2 to normal air temp will release even more energy.


The best bet would be to have a hybrid with as much batter capacity that can be afforded to carry/pay, with a LN2/generator system to charge the batteries.


Just some thoughts. LN2 actually has some measure of hope
whereas compressed air simply won't cut it.

ga2500ev


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## icec0o1 (Sep 3, 2009)

Personally I wouldn't want to be anywhere near a vehicle with a 100 gallon liquid nitrogen if it gets into an accident, especially in a non-pressurized, strenghtened container.


Although, thinking about it, if you collide with an ICE, it could spill over the engine or gas tank and put out any fires. Either that or explode. You wouldn't need the jaws of life either as all the metal that it comes incontact with would become brittle enough to kick down  Just hope none of it gets on you. .


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## samborambo (Aug 27, 2008)

A perfectly good thread derailed by bad science. Compressed air is a waste of time. The most serious issue is dealing with the freezing effect of any gas expanding. You'd need to burn fuel to keep the expansion turbine from freezing.


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## Moreforles (Aug 20, 2009)

samborambo said:


> Compressed air is a waste of time. The most serious issue is dealing with the freezing effect of any gas expanding.


saw a show where a moped was powered by 2 scuba sized air tanks, and maybe they had a freezing problem, but edited that part out...

It sound doable.... maybe a small sized test model.... mini van sized, and then work your way up, but even without compressed air.... maybe a big enough generator... weighing less and taking up less space than batteries and using less fuel than standard RV...

worse case, normally fueled vehicle, but everything except the drive system, running everything off solar/wind generators


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## Sunking (Aug 10, 2009)

This is Bill said:


> The long flat roof is ideal for solar panels. If my RV is sitting out doors all the time, then it makes sense to have solar panels. The extra weight and cost is a draw back at first, but the savings over time (and thats what solar is all about) would be great. 99% of the time an RV is sitting around at your storage lot or your house or even the camp ground. I would love to have the sun recharge the batteries for me, sort of like a full tank of gas a week, only not paying $250 and worrying if the gas is getting old as the RV sits through winter. And if my RV is parked in my side yard, then perhaps it's solar energy can be fed back to the utility company's grid, another cost savings plus over time.


 Well the roof maybe idea for putting solar panels on but, not near large enough to generate enough energy to amount to a hill of beans. You would need something on the order of a football field.

Assuming the roof has about what 4/m2? Well if you bought the most expensive panels on the market with 20% efficiency would be about a 700 to 800 watts that would cost you roughly $5K. With an average 4 Sun Hour day and conversion efficiency would generate about 2.2 to 2.5 Kwh per day or about 25 to 30 cents worth of juice per day. If you had a 100Kwh capacity battery would take you around 2 months to charge your batteries if you are lucky and self discharge did not eat you alive or the batteries don't sulfate up from being left discharged while waiting to charge up.  Physics and economical math suks, but so does the truth.


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## Jan (Oct 5, 2009)

Sunking said:


> Well the roof maybe idea for putting solar panels on but, not near large enough to generate enough energy to amount to a hill of beans. You would need something on the order of a football field.
> 
> Assuming the roof has about what 4/m2? Well if you bought the most expensive panels on the market with 20% efficiency would be about a 700 to 800 watts that would cost you roughly $5K. With an average 4 Sun Hour day and conversion efficiency would generate about 2.2 to 2.5 Kwh per day or about 25 to 30 cents worth of juice per day. If you had a 100Kwh capacity battery would take you around 2 months to charge your batteries if you are lucky and self discharge did not eat you alive or the batteries don't sulfate up from being left discharged while waiting to charge up.  Physics and economical math suks, but so does the truth.


It's a pretty big RV. So the roof would be more like 1,8x6=10m2. If you add a sunroof -I think that's what it's called- of the same size also packe with solar cells, you get something like 20m2. If you could tilt it all a bit to capture a few hours more. You could get something like 15-25kWh depending on your geographical location. Then it would take only 4 to 7 days charging a 100kWh pack.

But I agree with others who said you should redesign the solar RV from skratch. Weight, solar surface and airodynamics should be the key issues in that design.


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## Walter_Lars (Jan 12, 2009)

thinking outside the box a lil bit here what about a pickup pulling a trailor 
a 5th wheeler style instead of a normal RV camping trailor use a heavy duty flat bed trailor and build the RV on it in between the frame rails put the batt racks and some in the bed of the pickup replace the trans and drive line with a generator and mount the drive motor on the differential
the basic set as a modern Diesel electric railroad locomotive 
you would run the RV on the batts on flat road kick in the diesel engine for pulling the hills 
or running the engine when your driveing the diesel genset could produce more amps than needed to move the rv and would be able to charge the batts 
while not a true Electric RV running it on bio diesel would be green a hybrid RV diesel engine picks have more than enough power to run a very large genset 300 HP on ave My thinking is running a large genset for a couple hours would not be that costly 
the genset combo could be run in the RV camp at night would be queit 

here's another thought 
many RV's have a very small payload 
in fact a couple of years ago some RV were bilt on under size chassis GVW wise 
when the RV had full tanks of gas the payload was only 125 # 
so when your looking at a doner RV check the empty wieght vs the max wieght to make sure it can handle the added weight of the extra batts


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## camerondmm (Apr 28, 2009)

Just saw this: http://www.thunder-sky.com/products_en.asp?fid=&fid2=&page=7


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## toes (Jun 30, 2012)

Thinking outside the box: I was researching this compact RV of which I saw an example in town today: A Vixen 21 TD, built from 1986 until 1989. It was very innovative in that it was 21 ft long and just tall enough to still fit in a standard garage. It ran on a BMW turbo diesel engine with 115 HP and could go 100 miles per hour. Driven at highway speeds you could (supposedly) get between 25 an 30 mpg.

After looking around at used ones, I thought: what if I wanted to build something similar today? The designer Bill Collins (of Pontiac, DMC, and AMC history) mentioned that it would be impossible to find an existing chassis to build something like the Vixen on, but then I recalled the recent images of the Tesla S drive train with its flat battery and small electric aggregate.

What do you guys think?


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## TomA (Mar 26, 2009)

A love the Vixen 21!

Originally with BMW (also some US Lincolns) turbodiesel with a pop-up slant roof, then later with the GM 3800 gas (one of the curiously most fuel efficient GM engines ever...) and a fixed roof, these remain collectible and have a loyal following.

The problem is RVs need all-day range. Period. Why take an RV if the farthest you can go in a day is the next KOA motorhome park maybe 150 miles away with a 50A 240V circuit (which would probably pop a breaker anyway if you really pulled big current out of it...) 

Let's noodle this a little using the rough-and-ready 8kWh of LiFePO4 to one gallon of gasoline conversion number I've suggested here in many other posts. If that's greek to you, fine, you can search my other posts about it to believe/disbelieve it, but bear with me for a minute:

A gas Vixen 21 MIGHT get 25mpg if hypermiled and as heavy as you'd need to make it with a conversion full of Lithium, Probably closer to 20, but let's be optimistic and say 25. So to go 150 miles in it you'd need 6 gallons of fuel. That's 48kWh, so you'll need a 60kWh pack to stay above 80% DoD (105 or so 180Ah cells @ $252 each from Jack Rickard) that will cost you over $26,4060 before shipping. So Jack gives you a deal and you get them for $25k delivered. Still, that's a lot. Weighs 1300 lbs, too, not including racks and cabling.

Now, to charge it, say you get a whopper Manzanita 75A charger, (for $4500,) but of course you can't pull more than 42A continuous from the 50A whip at the trailer park, so at 42amps the best you're going to put in is 10kW continuous. Even at 100% efficiency, you'll take 5 hours to fully charge. Probably a lot longer. You're going to need a 13" motor or dual 11"s and a Shiva or two to move, so that's another, what, $20k-$30k? DC-DC and AC inverted power is going to be no trivial matter, what with air conditioning and all. 

Now the budget is up over $50k in components alone, maybe a lot more, plus you need the Vixen and a year or two to get it all worked out. If you guess wrong, and the rig can really only go 120 miles before stopping at an RV park with a 50A 220V circuit for 5 hours, (or a 30A EVSE for, say, 7 1/2 hours,) its not going to be a very satisfying build to use as an RV. Cool wedding limo, perhaps, but not an RV.

I dunno, not to be negative, but its a dead-end street, particularly when the guy with the TURBODIESEL Vixen 21 can pull nearly 30mpg going as far as he likes, switching driving with his sleeping passengers, and go from New York to Florida in one day while you go 125-150 miles two or three times a day (seeing nothing but the lounge, pool and playground in each KoA) for 3 days catching up. OK, that's starting to get negative, but here's my point:

The electric RV is an order of magnitude better and cheaper battery pack than we have available today away from being viable. Even the Vixen 21, which is the king of high-efficiency RVs, is less than workable. If the mileage of the glider rig was more like 18, like a Dodge Sprinter motorhome, you'll need an 83kWh pack at $35k and 1750+lbs to go 150 miles before you stop to charge for 7-12 hours. 

Much easier and cheaper to get a good ICE powered RV and enjoy using it now. 

Just my $.02


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## Caps18 (Jun 8, 2008)

Retired people have the time to go slow, more people should learn to enjoy the journey instead of just racing to the destination and back. There are places to go within 100 miles of wherever you are. Out West, the chargers might not be there, but there are national parks and RV parks.

Solar panels should be standard and mandatory on roofs. Not exactly for powering the wheels, but to power the RV when you are parked. I hate all of those little generators running all night...

While you would be better off and there are examples of 100% solar boats, I think there could be a few things modified and improved to get an EV RV to go 75-100 miles in one charge. 200-250 miles in a day. But most of the time would be just sitting around once you got to your destination. And 4-6 hours to recharge isn't a problem.

I know that I wouldn't be able to afford the fuel in a normal RV. I would like to see RV and electric motor/battery companies take their best shot at making it. Aerodynamic, fiberglass, carbon fiber, aluminum, and plastic, solar panels on the roof as part of the structure...air intakes in the front that pipe that air from front to back to disrupt the air vacuum/pressure difference...


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## toes (Jun 30, 2012)

I think TomA is right. The technology isn't quite there yet, but if Tesla can survive the next couple of years, I think this could get to be more real. The performance of the Tesla package is quite impressive, and it takes up so much less room which related it to the Vixen in my mind. The aerodynamics are a huge factor that seems to be largely neglected in RV design (and so is weight for that matter: heavy sofas, wood cabinets that look like residential ones, ...). With a longer wheelbase (the vixen was about 160 inches vs the Tesla model S 120 inches) there would be room for 25% more battery. the Tesla is available in a model that gets almost 300 mile range. So: the capacity isn't quite there yet to translate that to a larger, heavier, less aerodynamic RV package, but it is moving quickly into that direction.
As for cost: the Tesla Model S starts at $57k. Take away anything but the engine and battery and those might become reasonable to buy.


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## bjfreeman (Dec 7, 2011)

MotorCoaches (bus conversion) and transportation buses have been using the Allison EP50 for years.
There is some good solid data about using it.
Most Class C RV have a 500-600 HP ICE to be able to negotiate the grades at Hiway speeds. you are talking about 5-15 miles of 15% grade.
Most Transportation Buses use a combination of 190HP ICE with the EP50 that has two 96KW electrics that work in tandem with the ICE.
About the best Solar you can get on a 40 Foot RV is about 800 watts. The cost, currently, is about $1.23 per watt.
There are solar panels that are thin and prismatic to get the most from the Sun in stationary mode. They can also be walked on.
Why I don't have Solar is we have about 5 Weeks, if that, of sun in a year.
My goal is to eventually be powered by Hydrogen PEM cells.
Currently a PEM Stack is 150KW. The tanks would reside on the roof for maximum protection, as is done with the CNG based Buses.

Luckily my RV is all Aluminum, except for the Power Train.
It is an HEV, with a 250KW Generator powered by the ICE and 3 Phase AC squirrel Cage Motor that drive the 4 speed manual transmission. eventually will have motors on each wheel.
At 60 mph, on flat, I consume between 96Kw and 108KW, with 35 mph Headwinds.

the Battery Pack is 390 Volt 200Ah lithium pouches put in, in 2005. it is an undercarriage pack that is thin, but long and wide. It has fluid temperature control.

I have a DC to DC that take the 390Volt and boost it to 730 volts, to power the controller. When the ICE is running it charges the Battery pack and Adds it power to the DC Bus to the Controller.

As an RV, I have a inverter that is also powered off the Battery pack, for the 110/240 single phase AC requirements. Usually over night, the pack does not need charging. Most all the lights are LED based on 12volts. My heat, in stationary mode is supplied by propane. I adapted the Infrared panels to use a exchanger that ties into the circulation system of the ICE.

In short, I don't believe is will ever be practical, of have an ERV for the true Fulltimer, like me.


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## Caps18 (Jun 8, 2008)

If I had an RV, I would be driving it to where the Sun is. South in the Winter down to Baja Cali, Mexico and up to Alaska in the Summer (well, not too much Sun there if it is behind the clouds). Anyways, you could put 800 Watts of solar into the back of a pickup truck. My 8 solar panels are 25 ft long x 5.5 ft wide and they produce 1680 Watts optimally. I'm thinking it would be closer to 2500-3000 Watts of solar.

You might need to have fabric walls cut in a triangle shape to let you raise and lower the roof on a hinge to angle the panels when you are parked.

Fabric interior walls would probably be one of the compromises that would have to be made in order to get the weight down.

It would have to weight in at 5,000 lbs or less, which is hard to imagine when a real RV is 13,000-16,000+...
(1,000 lbs in my ideal EV will just be solar panels and electronics)

How about pulling this lightweight RV with a EV pickup if it was a 5th wheel style? That is the type I like the best.
http://www.littlediggs.com/littlediggs/2009/07/solar-mobile-trailer-home-by-vodafone.html

Or just in the bed of the pickup. Although you won't be able to last a long time in this style.
http://www.solar-green-wind.com/wp-content/uploads/2010/06/install_solar_rv-0851.jpg








With a solar pull behind trailer...
http://www.solarsnob.com/pictures/greentow.jpg









Is it possible to do it conventionally, no. But, I think that something could be built that would work.


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## bjfreeman (Dec 7, 2011)

most ev for transportation take a minimum for 10KW more like 50KW. how long do you think Solar would run a EV or even Charge the batteries, at the levels you mention?


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## PStechPaul (May 1, 2012)

I want to extend this discussion to thinking even further outside the box. An RV (or even a car or truck) can be very easily shipped from point to point by rail, which is overall probably five to ten times more efficient than highway travel. There is a company that specializes in this:
http://rvbyrail.com/index.htm










I have no idea what is costs, but it is likely less expensive than driving an RV especially if you factor in the cost of making it able to travel 200+ miles a day on electric power. 

Most campsites are likely to be within 20-50 miles of a major rail depot, so you could design the RV for a similar range. You could also consider having it towed part way, or have a generator to extend the range. You could also have a small vehicle for personal transportation if you want to drive the section covered by the rail transport, or you could just ship the small vehicle by rail as well, and ride as a passenger in safety and comfort. I doubt that it is a great pleasure to drive an RV 500 miles across desolate plains in Kansas. 

This option may be more expensive at this time because it is not done very often and there is little competition. But if rail transport is really much more efficient than highway travel, and if fuel prices really skyrocket, rail travel will become cheaper, and it will also relieve some congestion on the roads and make travel safer. If we can also encourage more long-haul trucking to make use of this technology, it will also relieve road congestion and damage and allow highway travel to be faster and more pleasant. But if we can get used to going by train on long trips, it will also provide rest and relaxation for drivers, or even an opportunity to conduct business while enroute, rather than having to concentrate on driving. 

I have not really heard much discussion about this option. Maybe there is a reason for that. But I think it should be considered. Trains already make very efficient use of fuel and they can run on pure electric via overhead lines in the vicinity of major cities. There has not been much emphasis on railroads because the trucking unions want to keep their thousands of drivers on the road rather than a few hundred rail workers. 

But IMHO the time is coming when we will all have to reduce our mad quest for high-paying jobs to support our materialistic and wasteful lifestyles, and adopt a life of more leisure, while we allow machines to take care of most of our work. That was the original dream of the industrial revolution, but somehow it seems we are not comfortable with sharing resources and having free time on our hands. I think our lifestyles are reversed. We should work two days a week and have 5 days of rest and recreation.


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## Caps18 (Jun 8, 2008)

bjfreeman said:


> most ev for transportation take a minimum for 10KW more like 50KW. how long do you think Solar would run a EV or even Charge the batteries, at the levels you mention?



At 500W (perfect indy car like RV) to 1000W (more likely) per mile, you couldn't go very far, this is true. But it should get you from one charger to another one, and help recharge the batteries while you are camped out (however most campsites have trees around).

I think a boat would be a better idea. 

I wish the train idea would catch on with motorists traveling across country. The rail system needs to be brought into the 21st century, not in terms of speed necessarily, but in terms of having 20 cars in a row that can take 3 vehicles. Have automatic restraints, and have the assembly sequence automated. The people would get into sleeper pods or hammocks. The train would then travel with very few stops from Chicago, Indy, St. Louis, New Orleans to Dallas, Albuquerque, Denver, Tucson, San Diego, and Seattle.


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## bjfreeman (Dec 7, 2011)

PStechPaul:
there are tours for this style already but you travel in your RV on a open car
http://www.youtube.com/watch?v=-VR6JQI8VCQ
unfortunately they were declared unsafe.
so where would someone stay. most definitely not locked up in a Hot box with not circulation and can't run a generator.

It is hard, though, to just call up the railroad on a moments notice. Even if you plan stopping at many places you can not route so you have continuous train support.
I check this out for my trip from west coast to East Coast, going to RV Jamborees.


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## bjfreeman (Dec 7, 2011)

Caps18 said:


> At 500W (perfect indy car like RV) to 1000W (more likely) per mile, you couldn't go very far, this is true. But it should get you from one charger to another one, and help recharge the batteries while you are camped out (however most campsites have trees around).
> 
> I think a boat would be a better idea.
> 
> I wish the train idea would catch on with motorists traveling across country. The rail system needs to be brought into the 21st century, not in terms of speed necessarily, but in terms of having 20 cars in a row that can take 3 vehicles. Have automatic restraints, and have the assembly sequence automated. The people would get into sleeper pods or hammocks. The train would then travel with very few stops from Chicago, Indy, St. Louis, New Orleans to Dallas, Albuquerque, Denver, Tucson, San Diego, and Seattle.


there are many ideas, most I have investigated.
I just shared my experience I am not interested in other thoughts.


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## PStechPaul (May 1, 2012)

It's a shame they discontinued this. I can understand the concern for safety and I'm surprised that the Mexican government would be so worried that they would stop this. I can understand it being banned by the US government and that of other countries, with a "nanny state" mentality and a litigeous populace urged on by shyster lawyers. But we have all lost something very precious by expecting others to protect us from our own stupidity and ignorance, and not allowing us to take full personal responsibility and do things that involve a degree of risk. 

Even if one were not allowed to ride in their own RV, this should still be a viable option. I agree that under current conditions such services would be costly and involve a major amount of long-range planning. But such ideas will very likely become necessary in the next 20 years or so when we finally start squeezing the last drops of fossil fuel from the limited supplies of "low-hanging fruit", as it were. 

There is the "AutoTrain", which runs from Lorton, VA to Orlando, FL. It states that the cost was $750 for one van, 3 adults, and one child. A 17 hour drive, about 1000 miles. 

http://youtu.be/HGT4zYQwhec

Assuming the van gets 15 MPG and fuel at $4/gallon, that's $0.26/mile or $260. But if you add other costs, and value your time driving at, say, $20/hour, then the total costs are comparable. If you could transport a full size RV for that price, then it becomes even more reasonable.

Give it time. I think this will become the way of the future, unless the "collapse" is so bad we revert to a primitive society of hunter-gatherers.


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## bjfreeman (Dec 7, 2011)

I can see those an long trips, in SUV or family cars.
But you miss the purpose of RVing.
it is to be unpredictable, and enjoy the side roads you find, as you going some where.
in other words it is the journey not the destination.


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## PStechPaul (May 1, 2012)

I understand the adventure side of RVing, but sometimes I think it becomes a burden to carry your whole set of belongings, and essentially your home, along to these places. The ultimate in adventure, IMHO, is to stuff everything you need into a backpack and set out on foot into the wilderness, and even better to go with a group or meet up with others on the trail. The aspect of traveling light and being in very close communication with nature has a very special appeal.

My arthritic joints and bad back limit my ability to enjoy such strenuous activity, but I enjoy camping in the basic KOA Kabins, and also some of the more diverse cabins available through the PATC:

http://www.patc.net/PublicView/Cabi...spx?hkey=3ff5555c-a743-4375-93cc-e6203a08cfba

A good friend worked for years for the USPS and dreamed of taking his RV all across the country and enjoying his retirement. But last I heard he has it parked semi-permanantly at a nearby KOA and he works there for spending money. I think he spends most of his retirement income helping his kids and he has not talked about his grand cross-country travel plans lately. I think he wanted to find a woman with whom to share his adventure, but it didn't seem to work for him as a pick-up line. Not many are willing or able to pull up stakes and just go galavanting around with someone they barely know. So he has also allowed his dream to slip away, and although he meets interesting people at the KOA, it's nothing like just being a free spirit. And I think the prospect of driving his Class A Motor Home, with his car and motorcycle in tow, from one campground to another has become too much of a chore and prohibitably expensive.


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## bjfreeman (Dec 7, 2011)

http://www.rvnetwork.com is a whole community.
I am 70+ and have some mobility problems.
I have lived in my motorcoach since 89.
I just spent 10+ yrs caring for my parents.
I am about to retrofit the Coach and take off.
I doubt I will Join the Snow Bird group when is ten of thousand strong.

And yes if is almost impossible to find a companion that share the closed in space as I do.


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## bjfreeman (Dec 7, 2011)

PStechPaul said:


> My arthritic joints and bad back limit my ability to enjoy such strenuous activity


This off topic but thought is was important.
http://www.lifespanmedicine.com/regenokine-program
The process starts at about $5K, the New health care should cover it.


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## PStechPaul (May 1, 2012)

That might be what I really need. I recognize the many factors contributing to arthritis and I probably have 90% of them. So thanks for the link. I will consider that.

Someone else I know claims that similar health problems can be caused by the mercury in dental amalgam fillings, and she said she had incredible improvement after having the fillings removed and partaking of a nutritional program designed to cleanse the body of toxins. But it's also possible that just the nutritional changes as well as the psychosomatic effect of expectations could have been the main reason.


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## jk1981 (Nov 12, 2010)

This is Bill said:


> The electric RV.
> 
> I don't like driving all day long, so traveling 200 miles at 55mph in one day is great. Besides this leaves more time for camp set up. Some mountain grades can be very steep so the ability to go at least 5% grade at times is a must.
> 
> ...


200mi @ 55mph is going to need something loosely in the region of a 300kwh battery. 3Ton and ~$100k of Lithium. Doable but ultimately pointless. <based on 6T weight, 0.65Cd, 5sqm frontal, 0.015Crr>

Adding/Re-tasking a generator to make it a series hybrid just makes it a really really expensive gas guzzler.

Solar panels won't make a dent in running this or charging the pack. Even if you can squeeze 1kW out of a big array and you get maybe 8hrs of good sun a day you're looking at well over a month to charge the pack.

Plug it in to a 50A outlet (110V?) and you could charge it in around two and a half days.

Yeah... I'd just spend the money on a stock RV and fuel.


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## bjfreeman (Dec 7, 2011)

jk1981 said:


> Adding/Re-tasking a generator to make it a series hybrid just makes it a really really expensive gas guzzler.


It is a given that for the storage Gas/diesel gives you the best bang for the buck.
And using a ICE to drive a generator is not the most efficient.
but most power is getting the RV up to speed, So this is where the Electric comes in.
Also it is a step till the hydrogen PEMs replace the ICE and generator.

an old saying if you have to ask the cost, you can't afford it.


> Yeah... I'd just spend the money on a stock RV and fuel.


However what is the cost to the environment


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## PStechPaul (May 1, 2012)

bjfreeman said:


> It is a given that for the storage Gas/diesel gives you the best bang for the buck.
> And using a ICE to drive a generator is not the most efficient.
> but most power is getting the RV up to speed, So this is where the Electric comes in.
> Also it is a step till the hydrogen PEMs replace the ICE and generator.
> ...


If ICEs were used only where they make the most sense, such as recreation and travel to remote areas, the impact to the environment would be minimal, AND fuel prices would bottom out to about $2/gallon. The major environmental nightmare is due to unreasonable long commutes by individuals in overpowered inefficient vehicles which spend most of their time in stop-and-go traffic or speeding 90 MPH trying to make up for lost time, or just venting frustration. RVs probably contribute no more than 2% of the total CO2 and noxious gases that harm the environment, and they very likely consume a similar low percentage of all fossil fuels. 

Also, RVs are large enough that they can make use of modern diesel hybrid technology, which may be able to achieve 50-60% overall efficiency compared to 20-30% for standard ICEs, and they may be able to incorporate scrubbers and other technology to reduce emissions. Because of their low overall percentage of fuel use, and because they are often driven and parked in rural areas near farms, they are prime candidates for biofuels. 

Unless there is a tenfold improvement on battery technology, I think all-electric RVs are beyond what is practical, affordable, and acceptable for most RVers. I would put more effort into solving the overall wasteful and inefficient and unnecessary energy consumption by the 90+% of people who take it for granted that they should live in a McMansion many miles out in the country or suburbia and make a 100 mile or more commute every day into cities to work at jobs that allow them to live such lavish materialistic lifestyles, yet have so little time to enjoy the natural surroundings and instead isolate themselves in their large climate-controlled rooms totally absorbed in video games, internet social media, and high tech entertainment.


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## bjfreeman (Dec 7, 2011)

PStechPaul said:


> If ICEs were used only where they make the most sense, such as recreation and travel to remote areas, the impact to the environment would be minimal,


the RV demographics are all over the place and the number total equal that of a city the size of new york. Most are mobile when tansistioning from a mild climate turning to blistering hot or freezing cold to a climate that is moderate.
the other group is one that plans around the country scenic drives.



> Because of their low overall percentage of fuel use, and because they are often driven and parked in rural areas near farms, they are prime candidates for biofuels.


most park in RV parks. Except for ones like me that Boodock far from civilaztion without be cut off Technically.


> Unless there is a tenfold improvement on battery technology, I think all-electric RVs are beyond what is practical, affordable, and acceptable for most RVers.


Agreed, HEV are the only way, except for fixed Transit systems that Have fixed recharging points.


> I would put more effort into solving the overall wasteful and inefficient and unnecessary energy consumption by the 90+% of people who take it for granted that they should live in a McMansion many miles out in the country or suburbia and make a 100 mile or more commute every day into cities to work at jobs that allow them to live such lavish materialistic lifestyles, yet have so little time to enjoy the natural surroundings and instead isolate themselves in their large climate-controlled rooms totally absorbed in video games, internet social media, and high tech entertainment.


Again I agree but not the topic of this thread.


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## Symmetrical (May 16, 2015)

Hi there.

I'd love to see this thread discussed a little further.

I just read all the way through and the overall impression I get is that most people think it would be too expensive to carry enough batteries for an electric RV (ERV). Is this still true in 2015? 

Part of why this appeals to me is that I'd like to travel as often as possible and I think there would become a point where the amount of miles travelled would justify the money outlaid on batteries, engine, conversion etc. What that magic number of miles is, I'm not sure. maybe somebody else can help with that.


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## Duncan (Dec 8, 2008)

Hi Symetrical

The calc is simple

Your RV is going to be big so lets say you can get 666watthours/mile or 1.5 miles/Kwhr
(that is about three as much as a small efficient car)
An RV will need to be quite aerodynamic to be as good as that

Batteries cost about $400/Kwhr - but you can only use 80% (or you kill them)
So allow $500/Kwhr

The rest of the stuff is not as expensive

So each mile of range will cost $333

If you want over 100 miles of range the weight of the batteries will be making the vehicle less efficient - so the cost/mile will go up - as will the weight - its a viscous circle


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## Symmetrical (May 16, 2015)

Hi Duncan

Thanks for the figures.

By my calculations, based on your figures, for a range of roughly 150miles, it would take a battery bank worth around $50k. for the sake of rough figures, we'll call it $60k

If a regular old RV is getting 8mpg, and gas costs $3.80 gal (roughly, going by a webpage), then that's about $2.15/mile.

So, if recharging is free, after about 27 000 miles, the batteries have paid for themselves when compared to the price of gas for driving that far. Of course, recharging is not free but I haven't figured out how to incorporate that cost into my pricing model yet. 

So (and stop me if I'm wrong - I'm not an expert by any stretch) it seems to me that an EV RV is worth it, if you're intending to drive more than 28,000 miles.

Thoughts? If my math/logic is flawed, shout out. If my 'break even' number is wrong, how many miles do you think would need to be traveled to justify an EV RV from a pure price perspective?


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## nimblemotors (Oct 1, 2010)

If you are trying to be 'eco-friendly', that is, conserve resources rather than waste and hog them for yourself, traveling by taking an entire home with you is about the worst thing imaginable.

A tent or a hotel is much more 'eco-friendly'.

If you are trying to be 'economical' in terms of reducing your cost to waste and hog resources for yourself by using electricity instead of fuel, this is a poor idea. 

A hybrid is much more cost-effective, as the engine will run in max mpg mode, and the electric will get the thing up to speed. I said the same thing in the other RV thread.


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## toes (Jun 30, 2012)

It keeps being stated that RVs are big and heavy (and have poor aerodynamics). The Vixen changed this. Why would we not use a Tesla platform and a lighter, more compact RV? Now Tesla has the superchargers which charge their battery in about 30 minutes.


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## nimblemotors (Oct 1, 2010)

toes said:


> It keeps being stated that RVs are big and heavy (and have poor aerodynamics). The Vixen changed this. Why would we not use a Tesla platform and a lighter, more compact RV? Now Tesla has the superchargers which charge their battery in about 30 minutes.


Nonsense. Vixen is big and heavy and has poor aerodynamics. 
Note that a Model S is also not an 'eco-friendly' car, it is a gross e-polluter.


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## toes (Jun 30, 2012)

Thank you for your "nuanced and insightful" response. Let me try to gather something useful out of it:

I am mentioning Vixen as a concept. I know that by today's standards it isn't particularly light or aerodynamic, but certainly significantly more than it's contemporary RVs were. How else do you explain the efficiency it could get out of a small car Diesel engine 30 years ago?

Tesla is as environmentally friendly as where the electricity it uses is generated from. It's a first step to change and proof that the technology works. Motorized transport is a luxury and not a necessity in many cases. Compared to vehicles in the same premium segment that Tesla currently plays in it is more efficient, safer, needs less maintenance, and is a lot more fun. After all: when we talk about RV-ing, it's a luxury, not a necessity.


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## nimblemotors (Oct 1, 2010)

Well, yes, waterboarding isn't as bad as real torture, it should be OK. 
Is that nuanced enough? 
As I said, if you want to be 'eco-friendly', drive a Prius and carry a tent.
If you want to be ego-friendly, drive a big honking RV and huge 'luxury' car, and I will call you an eco-a***, there is it clear now?




toes said:


> Thank you for your "nuanced and insightful" response. Let me try to gather something useful out of it:
> 
> I am mentioning Vixen as a concept. I know that by today's standards it isn't particularly light or aerodynamic, but certainly significantly more than it's contemporary RVs were. How else do you explain the efficiency it could get out of a small car Diesel engine 30 years ago?
> 
> Tesla is as environmentally friendly as where the electricity it uses is generated from. It's a first step to change and proof that the technology works. Motorized transport is a luxury and not a necessity in many cases. Compared to vehicles in the same premium segment that Tesla currently plays in it is more efficient, safer, needs less maintenance, and is a lot more fun. After all: when we talk about RV-ing, it's a luxury, not a necessity.


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## toes (Jun 30, 2012)

Hahaha. A Prius and a tent? Please. I will call you a pseudo ecologist, because that's what you are. If you want to be a true environmentalist: Hike and seek shelter in caves. And eat berries you can find.
Am I clear now?


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## ken will (Dec 19, 2009)

Everyone feels comfortable somewhere between, Gas-Guzzling for fun and minimal environmental impact.
If you are making the situation better, more power to you!

This guy draws the line here.


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## toes (Jun 30, 2012)

Very true. I love that picture.


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## Duncan (Dec 8, 2008)

Symmetrical said:


> Hi Duncan
> 
> Thanks for the figures.
> 
> ...


Problem if an RV gets 8mpg it is NOT going to be able to get 666watthours/mile
That is equivalent to about 15mpg (3 times as bad as a good light car)
So for a monster that only gets 8mpg you need to double my estimates 

The next thing to worry about is re-charge time
How much power can you draw at an RV park?
Keeping to my 15mpg example that is a 100kwhr pack
At 4kw that is 25 hours
OK if you are going to spend a few days - no good for heading off the next morning
If you are going to be drawing a lot of juice the RV park will probably want to charge you for it


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## Symmetrical (May 16, 2015)

Thanks for the thoughts on Prius' and tents. With the greatest of respect though, this is the electric rv thread 

What would the options be for recharging the kind of rig we're discussing here? 

Can the same batteries be used for day to day use, such as fridges etc?


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## Symmetrical (May 16, 2015)

I think we were posting at te same time lol

I was just throwing out 8mpg as a rough guess. Not sure how accurate it'd be.


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## PStechPaul (May 1, 2012)

Ideally, you may be able to ship the RV by rail to a point close to the campground, eliminating the need to drive it very far. If most of the driving is at 40 MPH or less, the W-h/mile should be much lower and a more reasonably sized battery pack would suffice. Here is a company that specializes in such:

http://uni-levelrailcar.com/index.htm

http://www.americanautoshipping.com/auto-transport-rail/

Shipping of an F-650 truck about 1000 miles costs about $600.

Potentially, rail transport could be much cheaper than driving an RV the same distance, but the actual charges may be much higher. I think rail transport is less than $0.10 per ton per mile, so a 5 ton RV delivered 1000 miles would cost about $500. The same vehicle at 10 MPG and gas at $3/gallon would cost $300.

[edit] Funny - I got two quotes for shipping an F-650 from Cockeysville to Minneapolis. The first was $195 and the second one that just came in was for $2149!


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## dougingraham (Jul 26, 2011)

Duncan said:


> The next thing to worry about is re-charge time
> How much power can you draw at an RV park?
> Keeping to my 15mpg example that is a 100kwhr pack
> At 4kw that is 25 hours
> ...


About the best you could do at an RV park would be a 240 volt 40 amp service which means 9.6kw. Actual charge wattage would be around 90% of this so 8.6kw. Take two 10kw chargers with you and connect to two of these and you can charge at a pitiful 17.3 kw which means a depleted 100kwh pack would take 5.8 hours. A Tesla Supercharger could do a 100kwh pack in less than an hour. A Chademo station could do it in about 2.5 hours.

Cost of the electricity to recharge that 100kwh pack at $0.12 per kwh is going to be around $13.33.


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## tenthousandclowns (Jun 21, 2012)




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## Caps18 (Jun 8, 2008)

That Tesla's top window either would be crazy expensive, or would need to be redesigned. That also would need to be driven to places where it is cold, because if it was sunny and nice outside, it would be well into the triple digits inside that greenhouse.

The idea is valid though. I could see doing this, even if it was a hassle to charge at the superchargers unless you park like this... I might consider it for the winter months out of the year pretty soon. But, I think finding a Tesla Model X with unlimited supercharging would be the way to go.


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## brian_ (Feb 7, 2017)

That conceptual illustration shows a cab area looking similar to (but not functionally the same as) the Tesla Semi. That's a useless design for a motorhome.


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## dain254 (Oct 8, 2015)

I recall reading another thread similar to this a few weeks ago and never posted a reply - There are two ways that I personally would go about this. The first would be to find a decommissioned or surplus electric commercial truck and convert it to a motorhome. At this point in time they are extremely rare, but I see one come up for sale or auction every once in a while - the biggest example had a 120kwh battery, so your range goals would likely need to come down or you'd supplement with a genset. 

The second option for converting an existing motorhome the elephant in the room is how to get enough battery - instead of building 1 giant pack why not build/use 2-3 smaller packs from vehicles like a Chevy Bolt, or Tesla S and switch between them like having multiple gas tanks? This way the daunting task of dismantling and wiring a birdsnest of a BMS is already completed by the original manufacturer.


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## brian_ (Feb 7, 2017)

dain254 said:


> There are two ways that I personally would go about this. The first would be to find a decommissioned or surplus electric commercial truck and convert it to a motorhome...
> 
> The second option for converting an existing motorhome...


A sound approach: either convert an electric van to a motorhome, or convert an engine-driven motorhome to an EV. That's how this thread started, with both of these options explored. This makes more sense to me than starting with a vehicle which is neither a motorhome nor an EV, and making it both, as proposed in another thread.

Since I just skimmed through this (very old) thread, one minor correction: the higher-capacity campground power service is 50 amps @ 240 volts (not 40 A @ 240 V or 50 A @ 110 V as mentioned)... but I don't think you want to push this capacity due to the poor quality of campground wiring, so the 40 A value is probably better for planning. Perhaps assume 30A @ 240 V (Level 2 charging at 7.2 kW) when "50 amp" service is available.

There have been a few discussions in this forum of EV motorhomes. Starting from a Vixen (mentioned earlier in this thread) or GMC Motorhome have both been discussed and seem the most attractive to me, but both are now rare and essentially collector's items.

A sampling (some are hybrid, rather than pure battery-electric)...
2010: RV conversion
2013: Looking to ev a motorhome
2017: RV / Bus ev motor?
2018: RV Project


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