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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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SHEV would be a better idea, IMO
by: Korbendalis

The core function of the SHEV is best demonstrated by Via Motors ( 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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