# Motor Home PHEV



## dwaz (Apr 21, 2008)

Hello,

I am considering an electric motor home conversion. At first this seems crazy, and there is really nothing on the internet about it. I understand the relationship between weight, drag coeficient, etc. and range, and obviously to go out of town it would have to be a hybrid. So I have come up with the following using the EV Calculator at 

http://evconvert.com/tools/evcalc/?...nd=5:sec=205:asp=60:rim=18:rr=0.015:bs=0.003:

Warp 9 Motor
60 12 Volt Batteries
Zilla 2000 Controller
360 Volt

Even when I jack up the vehicle weight and drag coef, at 60 mph I would still get 20+ miles of range and use 1500 Watt Hours per Mile. More calculations for hills need to be considered, but here are my questions:

1. Is the calculator coming up with reasonable numbers?
2. Can I provide power to the system from a diesel generator?
3. What size generator will be needed? I found a 6000 watt diesel generator on the internet.

Thanks.


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## Cornelius (Sep 15, 2007)

The trucking industry is moving toward hybrids, so eventually the RV industry probably will too. A 6 KW generator is likely to be way too small to keep the RV running, if that is your plan. You would probably need more like a 20 KW generator.

If nothing else, you can always recharge at a campground using a 50 amp campsite hookup...


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## dwaz (Apr 21, 2008)

Thanks Cornelius,

Yes, I would like to be able to keep it going on the generator. What numbers do I use to determine the kW size of the generator. As stated, I calculated 1500 Wh per mile. At 60 miles per hour, that's 1500 Wh/mile x 60 miles per hour = 90 kWh. Will 20 kW be enough?


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## aeroscott (Jan 5, 2008)

I'm thinking 20 kw would give 30 to 40 mph. but with starting with full charge and generator running , also running at breaks could add 10 mph to the speed . how about building a variable frequency generator based on a turbo diesel hot rod engine . your idea would be great for the off road long range trekker . also as batteries become better the generator size can get smaller . just reviewed your calculator, my 30 -40 is way off.


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## MrCrabs (Mar 7, 2008)

I don't like the gear ratios for that F250 in the EV Calculator. They look like the differential ratio is not accounted for in em.

I chose a small non aerodynamic truck and raised the weight to 6100.
I also put in 1 battery string, it looks like if you put in more than 1 string, it runs them in series instead of in parallel... (Click on details under any of the Range # Gear sections to see details of motor volts/amp, battery volts/amps.)

It looks like a ~8500 lb vehicle will need ~50 kW to keep moving at 60 mph.

This might be a good application for a series hybrid, if you can find the room for a large generator, engine, and electric motor on this thing.

Find a 75-80 Hp diesel engine, a generator like this one http://cgi.ebay.com/50KW-ST-Generat...yZ106437QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
And a battery pack.
When batteries are fully charged, the can provide low speed, short distance driving power. When they get low the engine starts up the generator. The generated power is used to move the RV and recharge the batteries.
At highway speeds, the generator is used to provide power to the motor, and recharge the batteries if necessary, once batteries are recharged, the engine/generator only needs to run enough to keep the RV moving...

It would be alot of work, but it might give you better gas mileage depending on how much start/stop driving you would do vs how much highway driving.

It would do better under stop/start driving, because the engine/generator would get to run at a constant speed, where efficiency is better, and makes up for the extra energy conversion losses. However on highway driving, at a constant speed, the extra energy conversion might hurt your mileage.


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## CPLTECH (Sep 14, 2007)

RE: Warp 9
Many who have converted a Ford Ranger or Chev S10 have used the Advanced 9’ motor (~28hp constant) or the slightly better (from the reports) Warp9. But in either case, hp is never enough to equal or outperform the orig 4cyl. So the question becomes, how does a big, heavy, non-aerodynamic RV benefit from adding such a puny motor? Adding an onboard generator (according to most on this forum) does not improve operating efficiencies.
Someone has been converting Tahoes/Suburbans into “hybrids” using a system to assist the big V8 to improve city MPG, but now GM just came out with a new hybrid Tahoe.


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## ww321q (Mar 28, 2008)

check this one out http://www.evalbum.com/1110
J.W.


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## CPLTECH (Sep 14, 2007)

Nice.
The bus motor is rated 100KW, the Advanced DC9” is rated 21.5KW at 144V at 28.5HP per specs. Warp9 is slightly better, I am sure. That means the bus has 5 times the guts and still only goes 45MPH! Motor homes are a luxury item and owners must be willing to pay the price. My neighbor gets ~8MPG and it sits in his driveway a lot.
PS. I like to camp, too.


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## dwaz (Apr 21, 2008)

Good input on the motor. Keep in mind that I am using a 300+ volt battery system. If it is geared right, it should be able to go 60 miles per hour, no problem. I may need to consider a more powerful motor, given the feedback.

Also, there must be some reason that hybrids are more efficient, even on highway drives since trucking companies are starting to make them for that purpose, and locomotives have been diesel electric for a long time. While I am not expecting 60 mpg, it would be nice to get 20 at today's pump prices. Some of the efficiency must come from the electric motor on hills and accelleration, as the diesel engine can just keep a steady speed while the batteries provide the boost.

In part, I am making a statement, we don't have to settle for 8 mpg.


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## MrCrabs (Mar 7, 2008)

dwaz said:


> Also, there must be some reason that hybrids are more efficient, even on highway drives since trucking companies are starting to make them for that purpose, and locomotives have been diesel electric for a long time. While I am not expecting 60 mpg, it would be nice to get 20 at today's pump prices. Some of the efficiency must come from the electric motor on hills and accelleration, as the diesel engine can just keep a steady speed while the batteries provide the boost.
> 
> In part, I am making a statement, we don't have to settle for 8 mpg.


Interesting stuff about those Hybrid big rigs. (A google search for "hybrid big rigs" turns up several articles).
One article said depending on how the truck is driven a 5%-60% improvement in mileage can be had. Local delivery and garbage trucks would gain the most.

They probably are designed just like car hybrids, a parallel-hybrid, just on a bigger scale... The gas/diesel engine can be sized to meet the power demand when cruising, instead of having to be sized larger to meet power demand for acceleration. The electric motor runs alone, or helps the gas engine at low speeds, and can also be used to help going uphill/passing once at higher speeds.

Diesel-Electric series-hybrid trains only need to be more efficient than a purely mechanical transmission to be worth it economically. Imagine the size and possible problems/inefficiencies with a transmission designed to transmit 1000s of HP from the engine to all the wheels. Instead they generate electricity, then convert the electricity back into mechanical motion. It also gives them greater control over each wheel (minimize slip/maximize torque) than a pure mechanical transmission would.

I started doing research on trying to make my own hybrid passenger car, but the electric only range was reduced because of the extra weight, and there was less room for batteries because of room needed for the engine/generator.
I'm not trying to tell you its un-possible, just trying to point out possible problems with trying to do this. You might have plenty of space underneath to store batteries. 

Is this motor home FWD or RWD? Could you possibly keep the stock drivetrain as-is and add an electric motor to the currently unpowered axle?
It could be used at city speeds, and possibly to assist on the highway.

One other possible problem is the GVWR of the motor home... Once you fill up with batteries you might not have ang weight left for passengers and all the stuff you would want in a motor home... Just something to think about...


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## Mastiff (Jan 11, 2008)

Nice post MrCrabs you explained everything I was going to about Diesel-Electric Locomotives.

To *dwaz:
*If you expect to use a Series-Hybrid design on your motor home, you'll need much more than a single Warp9 motor. (this is my opinion)

On a motor home, you'll need probably a Warp13:
http://www.beepscom.com/product_p/mo-00-08413.htm

Or at least a Warp11 or Dual Warp8/9's.

You need a Serious amount of Torque to get a motor home to start moving and most DC motors will literally melt if put under too much strain.


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## dwaz (Apr 21, 2008)

I saw the email address of Bill B, one of the people involved in the bus project listed above. So I sent him an email. I am starting to think that someone more knowlegeable than me would need to be involved in the design of this. Here is what Bill said:

My experience with large EVs is limited to these (slow) APS busses. They have a 100 kw ac motor that weighs about 350 lbs direct coupled to the differential through a 2:1 gear box. They will do about 45 on the flat with a tail wind (smile). the manufacturer claimed a 95 mile range, we rarely go over 20 with plenty left. They DIE going up even a small hill sometimes dropping back to 20 mph, this being basically empty as it hauls demonstration equipment and not people for our school outreach program. There is two parallel strings of 6volt Nicads for about 350 volts nominal. Given this I would think you would need 250 kw or more to get a continuous freeway speed and still be able to climb reasonable hills.


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