Electric school buses are coming....can RV's be far behind ?

[99phantoms]

Originally Posted by pasdad1

The thread has been discussing making the RV a "series" hybrid not strictly battery only. With a large enough on-board generator, the batteries are mostly a buffer for reserve capacity. Since an RV needs a generator anyway.....this approach makes perfect sense.

Along that line... this may be the future of RV powertrains:

https://nikolamotor.com/one

(short video)

https://www.youtube.com/watch?v=B52MpalkZsE

(unveiling)

https://www.youtube.com/watch?v=wLidTCqAAtY

Hope they succeed.

[TonyDi]

I can't imagine the size of the battery bank that would be needed to power a 50,000 lb MH for 3-4 hundred miles. Battery technology is going to have to take a quantum leap to do this. The weight of current batteries would be huge. There goes all your storage space.

[akaJimbob]

Originally Posted by TonyDi

I can't imagine the size of the battery bank that would be needed to power a 50,000 lb MH for 3-4 hundred miles. Battery technology is going to have to take a quantum leap to do this. The weight of current batteries would be huge. There goes all your storage space.

Well I saw pictures for a local delivery coca-cola truck that could go about 80 mi per "charge". The battery pack was the width of the trailer (8'?), and 4'x4'. They were swappable, so they could come back in and in 20 min have fully charged batteries.

Lead-acid would weigh thousands of pound, for sure. And I've yet to see a lithium battery of that capacity (could you imagine the fire risk of that,since Li provides both fuel and oxidizer?)

[nothermark]

Originally Posted by pasdad1

I don't think a semi-truck is at all the same use case as a RV. Most RV'ers that travel 200-400 miles, then stay for 2-3 days before moving again, would completely benefit from this. A semi-truck is in operation constantly except for rest time for the driver.

When they become available, it will still be rare to see one, as it will take decades of attrition to see all the old fossil fueled vehicles go to the junk yards....so it would be rare for more than one or two to be in the same campground at the same time.... this would not tax the electrical infrastructure excessively.

Remember you might easily have a 25kw generator in one of these hybrids (instead of a 8kw one common today).....so you don't need as big a battery pack. With the generator offsetting a portion of the total power drain, the batteries last for many more miles.

Some folks use the trip as the adventure. Most RV owners seem to be more concerned with getting somewhere that they can set up for a while. That makes the 600 mile day for a couple of days a minimum mandatory requirement. Even folks who dawdle want the ability to move if they need to.

1 horsepower electrical is 746 watts in theory. Adjust accordingly when you look at generator requirements. 1 horsepower is also 550 ft-lbs of work. There is some fudge factor is the conversions because they are inefficient so those numbers are a minimum. Motors in general can go two ways, slow and very heavy because of the high torque load or fast and lower torque but then needing a substantial gear reduction to do road speeds. Either way you get some heavy hardware to haul around. All the advances in technology have to stay within those basic facts of physics. We do better materials and go from 20% efficient to 80% efficient but still stay within those parameters. Most of the improvements also come as added cost.

Given the numbers above your 25 KW generator is 33 HP and probably is driven by ~50 HP engine.

Modern solid state switching devices have made some formerly exotic controls fairly easy. Things like variable speed drive come to mind. OTOH the power requirement for large horsepower engines creates it's own balance of high voltage against high current and either way a lot of interesting and expensive power handling components.

Those reasons and some following of battery hybrid cars tell me that we might see some limited range experimental units as show pieces but we are a long way from seeing an off the shelf OTR tractor or even MDT truck setup that can do 400 or more miles/day at speed. Those commercial sources are what the RV industry parasites on for components. They are a much larger demand so we can take advantage of their economy of scale to significantly reduce cost.

[nothermark]

Originally Posted by pasdad1

I believe that is the most simple definition of the term....so they are a "hybrid".

Not diesel only. Not electric only.....but a "hybrid" of the two technologies.

All the hybrid gets you is short term power for acceleration of a small hill. There is still the basic problem of producing enough power to move the load x distance at x speed. One has to either make that power on board or store it before hand. A hybrid does some of both. It uses the fuel engine to put back some of the stored power while in low demand mode. Not too bad with a small frontal area car but a real issue with a large frontal area RV. If you want the ceiling height and width you are going to be pushing a lot of air out of the way. At highway speed that is the major load. Translate that to direct drive from the generator plus maybe some power to bring the batteries up from the last hill.

[RPreeb]

Originally Posted by pasdad1

I believe that is the most simple definition of the term....so they are a "hybrid".

Not diesel only. Not electric only.....but a "hybrid" of the two technologies.

My point was that that diesel electric locomotives are not designed like or intended to be used the same as a hybrid car. They don't have or need a large battery to run the the electric motors at startup. The diesels don't shut down at stop lights, etc., they are under power driving the generator at all times. For that reason I did not compare them to the hybrids being discussed in this thread. It's a similar technology used in a very different way.

[Scarab0088]

The same arguments WRT hybrid drive. But, if you owned and used one, the benefits are obvious.

The electric drive motor is always there as an assist. And to provide regeneration during deceleration. This allows the vehicle with a smaller engine to have big engine performance.
The electric motor provides a boost at EVERY stop and EVERY uphill...it all adds up.

Example: Our 10 year old Hybrid SUV gets 30MPG (combined). It has the same performance as that models biggest engine which gets 16MPG. The difference in initial cost was long-ago returned in fuel savings.

An all electric drive RV? - Doubtful. But, a Hybrid or boosted electric like the Chevy Volt? - Probably coming.

[wa8yxm]

Originally Posted by nothermark

Off hand I don't recall self driving in 5 years 50 years ago. I do recall self driving cars as well as self aware computers. .

Most people do not know this but we have had Self Driving cars for well over 50 years.... Many amusement parks have a "mini-car" ride, where the cars are set over a rail. Though you can turn the wheel and steer, if you do not the car has rollars that will engage the track so it goes around the loop same as if you drove it.. Well, set those rollars close to gether and you have an actual self driving car from well over 50 years ago.. It was never a production model, but, as it turned out, it is the model for the amusement park ride.

Let's See. When I took Fortran for Scientists and Engineers (Fortran IV) it was what, 1969 or 1970,, We used an IBM 1400.. About this same time a company called MITS was formed by a consortium of 3 editors from Popular Electronics, they producd the Altar 8080, the first real "microcomputer" and Frank Hayes wrote a song called the S-100 Buss.. Now as it happens I remember that song.. Frank is a good guy, he's helped me enter the world of public performing musically (He played while I sang).

I've seen an Altar.. but shortly after I was back at College studying Electronics.. I used their Micro.. this would have been mid 70's I think Possibly early.

We used punch tape and a Teletype machine to access it.

Then in 1983, I got my first "home" computer.

There is more trivia in my computer banks.

[George Schweikle]

Lexington KY just introduced a couple of electric only busses. In the newspaper article was a picture of the recharging station that a bus needed to use after every trip.

Originally Posted by akaJimbob

They can't even get small semi's (in-city) to be able to deliver locally. Coke tried, had HUGE battery-pack swapouts. If they can't go local, how you gonna do 200mi?

The math will either bear it out or it won't. Battery tech simply ain't there, and likely won't be for a long time, if ever.

Remember you have a 10-20% loss both charging and using a battery - now imagine that at the scale of an RV battery.

Another, simpler way to calculate it- how many KW of energy (in diesel or gas) does it take to move an RV 200 miles?

Now build a battery w/40% more capacity than that (to allow for charge/consumption loss)

[pasdad1]

This must be the one. This is already "old" technology.....battery electric technology advances as quickly as computers did when they were following "Moore's law"

This one has 200 mile range and can recharge in 10 minutes. If it had a large generator on-board ....making it a hybrid....it could easily go 400 miles or more.

In 5 years the technology will be nearly twice as good as it is now.

[KSagal]

Couple things...

1. Company I work for now makes solar power inverters. They started as a company that made electric cars, as the inverter is important in the taking power out of the batteries to the motors is done with a large loss, reduce the loss, improve the range, or feasibility. The company sold the technology for their electric vehicles to south east asia 8 years ago. Working buses existed at that time.


2. Movies from the 80s said that my car would fly by now, and my skateboard would hover.

3. Movies from the 50s said that we would have colonies on the Moon and Mars by now.

4. The current generation will not be able to tell the difference between real history and the history they see depicted on television. Hopefully the discovery channel and not Hollywood block busters, but just the same, Ben Hur will be more real in the eyes of my children than a text on the Romans.

5. The technology will continue to improve. There are lithium batteries that will not burn, but they take longer to charge as well. There are new technologies all the time. Each car show prototype is more likely to have small bits of the tech incorporated before the whole thing. Once financially viable, it will take off. So, they will be here, if they make sense. But we have a moment or two before they get here...

[jharrell]

Originally Posted by pasdad1

This one has 200 mile range and can recharge in 10 minutes. If it had a large generator on-board ....making it a hybrid....it could easily go 400 miles or more.

No the one that charges in 10 minutes has a 49 miles range and that's using a 350,000 watt charger!

The 200 mile range bus takes 3 1/2 hours to charge and the battery weighs 5000 pounds. To put in perspective it would take 36 hours to recharge on a 50 amp circuit at the campground, full bore nothing else but charging at 12,000 watts.

This is cool stuff but your going to have to give up a lot on a current RV to put a 5000 pound battery and a few thousand pound generator to come close to what we have now for much less weight. Most diesel pushers have a 800-1000 mile range with under 1000lbs of fuel, I get 500 miles on my gasser with 500 pounds of fuel.

[TechWriter]

Like some of you it seems, I grew up expecting to see missions to Mars, rooftop helicopter pads, and monorails as a fact of life by this time. Guess not. However, we do have a 300 mph mag lev train operating in China.

Nevertheless, I really don't see electric RVs in the cards for the near future. However, the near instantaneous full torque available at startup from electric motors makes them mighty attractive.

On the other hand, battery storage technology is far ahead of what many of you imagine. See PBS's NOVA Search for the Super Battery.

Finally, even nuclear power might become "friendlier" with newer reactor types like molten salt . . . another NOVA The Nuclear Option.

[nothermark]

FWIW Moore's law is in trouble. I am a bit surprised it made it quite this far. When they had to shift to x-ray lithography for the die masks I started to wondered where next. That was the driver behind adding cores instead of shrinking transistors to get faster processors. Speed seems to have topped years ago. Adding cores has another overhead bite in the control software to divide tasks and combine results. Here is one perspective:

https://www.technologyreview.com/s/6...dead-now-what/

Batteries have a similar issue. A lot of experimental work goes back to the 1800's for any common materials. Better understanding of the chemistry and physics involved has yielded some improvements in construction and materials but they are essentially issues if improved packaging allowing some more nasty combinations to be usable by the general public. Lithium batteries fall into that category.