Turn My Big RV Into a Plug-In Hybrid?

by Vernon
(Cleveland, Tn)

Hybrid RV Wannabe?

Hybrid RV Wannabe?

I've got a 31 Ft RV that gets 8.5 mpg.
Would an AC electric motor or 2 in conjunction with the 8.1 liter gas engine increase the gas mileage in an RV?

Hi, Vernon -
This is a really good idea, bordering on brilliant.
I recently spoke with Dennis Bieschke from NetGain Technologies (the same company that makes the high-quality "WarP" and "TransWarP" DC electric car motors), about a new product NetGain's developed called the Electric Assist System, or EAS. It includes an appropriate EV motor, a computer interface called EMIS, and a battery pack, and it turns large gas-hogs into plug-in hybrids, increasing the gas mileage by 26 percent or more. Sounds like just what you wanted!

In fact, the worse the gas mileage originally, the more the electric motor assistance will improve it. It was originally designed for those medium-sized delivery trucks that run all over town getting 10 mpg, burning up money and carbonating the atmosphere; )

Good news: It doesn't cost much to convert (around 7 thousand dollars) and it doesn't take much time, either (about one day of shop time).

A couple of things to say about this, though; first, the EMIS talks to your vehicle's computers to decide when to apply the electric motor assistance. If you've got an older RV (pre-1996), that's not currently possible with their EAS, so you'd have to configure something yourself. Second, the electric motor needs somewhere to live along the drive train, and rear wheel drive vehicles seem to have the most room to do that. Other drive configurations are in the works, but not yet developed.

It's no secret that I like the AC motor, for big vehicles especially, but I would think that a DC motor might work a little better for this purpose (that's what NetGain's using), because of the "instant torque" factor. I may be wrong, though.

Anybody else wanna jump in, here?


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Big engines aren't that bad. Ad Volts to make it better
by: Lee Klemetti

All large RV's are thought to be gas hogs. Very true. The larger 8.1 Chevy engine in my Winnebago loafs along at 2500 rpm @ 60 mph.

Generally I get 12 mpg. I'm learning the hypermile techniques to add up to 8 mpg.

Add an electric motor to the drive shaft as a load helper will make for a big improvement in fuel mileage. My rig starts at 2 mpg, then as speed improves the mpg is 7-8 mpg. When over 50 mph the mileage levels out to 12-18 mpg, which fluctuates greatly. With the electric motor helping out the power load the gas engine will not use as much gas as long the acceleration is moderate. This is what happens with my Prius.

My sweet spot for mileage is 58 to 60 mph.

I hope to average 15 mpg.

Cheers, Lee

Hybrid rv ala Prius
by: Kurt Steinmann

After traveling vagabonding in my 2011 Prius, with a attached tent by Napier, and a 1000w inverter, I'm convinced hybrid is perfect for camping because of the endless electricity.

If one could marry the dc drive motor to aid the big diesel engine, and mount the small gas engine and big battery in the truck bed, we 5th wheel haulers and big rv drivers would pay up!

Currently I boondock using the Prius to keep the coach batteries charged, via an inverter and trickle charger, and run an extension cord into the coach for a power strip. Works great for electric security.

Pipe Dreamer
by: sls4ak

I have an old (1985) Toyota Dolphin motorhome, it gets 14mpg. The idea of being able to boost the power up hills, and increase fuel economy is intriguing. If I could also use wheel hub motors to have at need occasional awd would be awesome. Having additional house battery capacity wouldn't hurt my feelings either.

A bolt on intermediate motor between the engine and transmission may be feasible (as a teen, I often shortened driveshafts, moved motor mounts, cut out and redesigned firewalls, etc.)but the awd thing would be too cool.

What about solar for 4 kW
by: Anonymous

"Unfortunately the total road load of a bus cruising at a constant speed of 60 mph on level ground is over 100 kW..."

LG is now selling solar cell packages that produce 400W from a set of cells 79.69 x 40.31 x 1.57 inches, so roughly 6.4 feet by 3.5 feet. so if you have a 30 foot roof that's 7 feet wide, then just short of 10 units could fit on your roof producing 4000 watts if my math is right. That would at least slow the drain down a bit, particularly at lower speeds. I *THINK* it could keep you going at 15 mph permanently.

a powerwall stores 14kwh, but the larger Powerpack 2 stores 200 kwh and is 86.0 in × 32.4 in × 51.5 in.

Solar panels on roof
by: Anonymous

What if you add on the roof 15 solar panels,345W each?
That could at least 10 miles/hour to the range.
15 * 345W = 5.1kW

Is it possible
by: Anonymous

Just curious could you make a class a all electric with solar panels on top of roof to help charge while driving?. And line the battery's along the whole length of Rv

smaller gas engine in hybrid motorhome
by: Pat

Are you as forgetting the additional power offered by an electric plus gas or deisel?. A reasonable sized gas or deisel for cruising could be smaller than usual, with battary driven electric kicking in on the hills or when accelerating. And the generator could kick in to charge the batteries when needed. You want the generator anyway, and added battary power would come in handy when parked, and they could be charged on solar and/or wind.

Batteries not an issue Tech wise...
by: Anonymous

Batteries would not be all that much of an issue if you can afford them. Tesla cars are currently using close to 500 Kwh batteries at the moment and that is in a mid size car. An RV could carry far more I would not be supprised if designed correctly a battery for a 100% electric RV being over 10,000 Kwh only taking about 5 inches of the full lenth of the bottom of the RV. The major issue with it would be cost. I would expect said batery to cost 30,000 usd at least. Maybe once the dual carbon batteries are out it will be better, and cheaper.

A little of this, and a little of that...
by: Anonymous

Tis true that the long flat haul thru the mid-west and similar flat lands would play havoc with straight battery power, however, using a variety of inputs from any reasonable source (regenerative braking using wheel hub motors; a photo-voltaic skin for solar, a small constant velocity propane/fossil fuel/fuel cell motor such as used in locomotives, and even some sort of wind turban) could help offset these difficulties.

lots of power
by: tom

if you can find a spot for these batteries you will have lots of power for the house as well only makes sense to duel porpsie everything most RVs use DC genorators that use inverters to give ac 120/240 the big issue i see is the 100 kw power to get to 60 mph i doubt its that high your likely looking at 300 hp to maintian 60 mph and i have just seen motors for sale that can provide 300 hp each and tagged togather to give 600 hp now that would be able to push most any RV out there and if each wheel driven by its own motor or motor set the extra battiers can go above the drivers cabin if you do not want a bed there smaller gas tank you about the same on storage libi

Utilize Hydraulic assist motors
by: Rob McLennan

I am designing a Hydraulic motor configeration to generate torque on startup, and storing High Pressure retention on Braking. I am planning on using the drive shaft for the pump. Mount the motor on the opposite side of my open end drive assembly.
Current Motor home is a 2005 Rexhall Rexair 8.1 Vortex engine average mpg 8.5. I am hoping on getting a 50% increase.

Use Less Fuel with Series Hybrid
by: tapps57

I would like to retrofit my RV with Electric Motors, batteries, and generator so I can use less fuel.

I purchased a RV, Thor Motor Coach 23 footer sitting on a Ford E Series Chassis with a Triton V-10 gasoline engine. I drove my family to Arcata, CA from Roseville, CA, to move my daughter to Humboldt State University. The RV got eight miles to the gallon. I found this very painful at the pump and very bad environmentally.

I believe the Technology is here now to retrofit vehicles with Electric drive motors and a generator set to create a Series Hybrid. Along with Controllers (computers and software), Batteries (Liquid cooled Lithium Ion) and other electronics, the gas mileage would be improved, thus, using less fuel. The environment needs this concept now. Technology makers who are currently working on the Series Hybrid concept: Wrightspeed, VIAMotors, AMPElectric, ACPropulsion.

Electric motors have plenty of torque to move large vehicles. Wrightspeed Geared Traction Drive is a great concept to assist the electric motors. The Capstone Microturbine is more efficient and cleaner than a small ICE to produce electricity.

SHEV would be a better idea, IMO
by: Korbendalis

The core function of the SHEV is best demonstrated by Via Motors (viamotors.com/powertrain/) or by any diesel locomotive. To use an internal combustion engine at constant speed gives it the best efficiency. Combining that with a generator, provides a power source. Batteries generally are used as storage (and for spikes in demand) and an electric drive motor turns the wheels.

Electric motors are used in locomotives because of the extremely high torque at low-speed and the fact that it is merely a change of polarity to reverse direction. Electric motors can be run in either direction at all speeds. Additionally, electric motors tend to be smaller than internal combustion engines and can be more easily connected in-line with wheels.

Most automobile manufacturers still cling to the notion that the motors must drive in parallel (PHEV), they don't yet seem to conceive of a reliable method of implementation that could best suit the transition to SHEVs. Old habits die hard?

As RVs tend to have a great deal of under-carriage storage, it might be reasonable to sacrifice some of that space (or possibly just rearrange it) for the SHEV drive-train. As noted by a previous comment, RVs have generators. This space could be utilized instead by batteries or the generator connected to the primary engine. I have read that Via Motors recently replaced the original 6L V8 in the Chevy models they use, with a 4.3L V6. It may not be necessary to keep a massive 8.1L engine in 35-ft A Class Pusher, once it is converted.

Another idea that may be considerable is that rather than have 1 or 2 large electric motors powering the wheels through a differential. All four wheels might instead be electric wheel hub motors. This would add to the potential of all-wheel drive, and assistance of braking energy regeneration.

utilizing existing components
by: Anonymous

RVs typically already have batteries for cabin power, often have generators, and have regular access to 240V power for recharging--unlike cars, which are still waiting for recharging infrastructure to happen.

I would think that by adding electric drivetrain you could improve mileage by upgrading capabilities of existing components, but wouldn't have to add as much as, say, a hybrid personal vehicle.

Also, space is not as much of a concern.

Bigger vehicle electric drives ??
by: Dan Bentler

Doing a motor home huh??

Good thought. Nothing new here. Kenworth is building a hybrid truck and has sold one to Dunn Lumber in Seattle. Maybe talk to Kenworth?

I am in planning pipe dream stage of going into business doing electric on heavier vehicles up to say 10,000 or so. I will not compete with Kenworth - they are too good and too experienced and have more engineers than I. They also have more leverage purchasing power with engine (Cat Cummins GM etc) and driveline components (Eaton Clark etc) than I.

OK so what will work?
Electric only either AC or DC would be great when in town and between a lot of stop lights. That is where electric drive excels.

A small generator would share the load imposed on the battery when running and recharge the battery at stop lights or parked.

Where electric only falls apart is on long hauls. You will need an additional power source unless you want to drag 10 ton of battery.
One method is have a large generator (30 Kw or so) to drive the motor and float the battery. Fairly weight intensive and probably not best option. As a retrofit this may be best option.

SECOND is to take the lesson from submarines. Run on battery until you need the engine. Clutch the engine onto the motor and drive line and drive both with engine AND switch the motor from motor mode to generator and recharge the battery. Getting complicated and expensive here but it is nothing new - just takes engineering and bucks. Would require complete redesign of driveline.

Dan Bentler

Highway PHEVs don't do as well...
by: Anonymous

I too long for the day when I can travel this great country on electricity alone. Currently the main issue with driving an RV on electricity is that the typical profile of an RV is highway driving at constant speed. You don't see much regenerative braking benefits.

The upside, is that cruising requires less power than accelerating and an appropriately sized battery may keep you coasting for quite a while.

Unfortunately the total road load of a bus cruising at a constant speed of 60 mph on level ground is over 100 kW. That would mean to drive just 60 mi [1 hour of driving], you would need 100 kWhr of batteries...that is a lot.

You could supplement this with a bit of gasoline in any ratio you want. But you still need lots of energy.

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