Jun 152008

I’ve seen many blogs, forum posts, and whatnot about all-electric RVs, and similar writeups about hybrid RVs, but I’ve never seen a detailed description of the advantages of bringing the two together into an all-electric hybrid RV.

So, what am I talking about here? An RV that is both all-electric and hybrid.

An all-electric RV is one without a propane tank. Most modern RVs provide all of the comforts of home, including space heaters and air conditioners; kitchens with ovens, stoves, and hot and cold running water; bathrooms with flush toilets and home-style showers. Typically, the space heater, water heater, stove, and oven all use propane to heat the air, water, or food.

In an all-electric RV, the propane systems are replaced by equivalent electrical ones. This has the advantages of simplifying the overall RV design, and removing the need for carbon monoxide sensors and heat-robbing vent holes. On the other hand, heating water and food requires a prodigious amount of electricity, far more than a single 12-volt “coach” battery can usually provide. Thus, the all-electric RV needs to have a bank of coach batteries, and a relatively heavy-duty and complex electrical system to support them.

An all-electric RV is still like a standard RV in that it has a separate battery for the engine, and another for the coach, and these two batteries are kept isolated from each other so that usage of the coach battery doesn’t drain the engine’s battery and make it so that the RV’s engine can’t be started.

A hybrid RV would be similar to a hybrid car: it would use a combination of a gasoline or diesel engine plus an electric motor to provide motive power. The motor would perform regenerative braking, so that some of the energy lost while stopping the RV could be recaptured. Overall, the hybrid RV should be somewhat more efficient in terms of fuel mileage than an RV powered by a standard gas or diesel engine. Even a few additional miles per gallon is a big gain in an RV that might typically get somewhere between 6 and 14 MPG. For example, going from 6 to 8 MPG in an RV is equivalent to going from 30 to 40 MPG in a compact car.

The hybrid system will require that the RV has a large bank of batteries to power the electric motor. This adds weight and complexity to the RV, but also has some very interesting advantages for RV owners:

  • The hybrid’s batteries would provide a huge amount of electrical storage compared to a typical RV’s coach battery. More than enough to make an all-electric RV possible, and even convenient. It is conceivable that the hybrid RV’s users could use their electric stove, air conditioner, and water heater simultaneously without putting an undue load on the batteries or requiring the use of a generator. Thus, the propane tank and all of its limitations, hassles, and requirements could be completely eliminated. Overall, the RV would be simpler to use and maintain.
  • The hybrid batteries would also eliminate the need for separate engine and coach batteries. The one huge battery bank would handle all of the electrical needs. Since the hybrid system’s computer would need to carefully monitor the battery state anyway, it could also warn the users before their coach usage lowers the battery bank’s charge to the point where the engine might not start.
  • Hybrid engines are fairly efficient and very quiet electricity generators; they are typically much more efficient, far quieter, and more reliable than the generators included with most RVs. In an all-electric hybrid RV, the engine could be used for all electric generation needs, and the generator could be eliminated. This would be a great feature, both for the RV owners and the people who are parked next to them, since no one would be forced to listen to the racket of a generator in the middle of the night. It would also reduce the RV’s overall weight and complexity.

How could an all-electric hybrid RV be built? A good place to start might be to look to the past. During the 1980s and early 1990s, many RV coachbuilders used a Toyota truck chassis as a platform for their smallest Class C RVs. These RVs were noted for their excellent fuel efficiency and the famous Toyota reliability. They commonly used a V6 engine, although some RVs successfully used a smaller 4-cylinder engine. Nowadays, Toyota produces trucks and SUVs with hybrid V6 engines–engines that are just as reliable and significantly more powerful than the ones that were once used in the small Class C RVs.

If Toyota makes a heavy-duty truck chassis with a hybrid V6 engine available, the RV coach builders would have all of the really tricky work done for them; they could simply create an all-electric version of their current small Class C coaches on this new platform. The hybrid chassis would need to have significantly higher weight-carrying capacity than the ones made during the 80’s and 90’s, since it would have to be able to carry both the hybrid systems’s heavy battery packs and the weight of a fully-loaded RV coach.

Once the basic ideas are worked out, Toyota and the RV coach builders could expand into smaller Class B all-electric hybrids and full-size Class A all-electric hybrids.

My guess is that many people who enjoy the RV lifestyle would be extremely interested in an all-electric hybrid RV, and they would likely be just as interested in the new features it adds as in the fuel economy it brings. I know that I would be.

 Posted by at 9:49 PM