Will hybrid drivetrain simplify and make for better Class B?

[Chance]

And I don’t mean as it affects how the vehicle drives, but rather how the drivetrain can be integrated to provide “house” RV needs. Sorry for length, but it's difficult to cover subject in few words.


In reading details of Honda’s new and simpler series-like hybrid system (series with mechanical direct-drive lockup at higher speeds) introduced on new Accord, it immediately made me wonder just how this kind of system would benefit a Class B RV. The same could be said for any kind of RV (like larger Class As or Cs), but mostly for smaller Class Bs because of limited space and available options that can be added easily.

So why does it seem better to me? On surface it seems much of electrical power needs for an RV would already be in place from the factory. Main changes may just be limited to software revisions for the most part. And software, when mass produced, is relatively easy, inexpensive, doesn’t require space or adds weight, and so on. By the way, I’m thinking in terms of Honda’s plug-in hybrid option in particular which has mid-size battery pack that would benefit RVing to a greater degree; although other hybrids should offer similar advantages.

For example, an electric air conditioner doesn’t require the engine to run at all. This should eliminate the need for a roof mounted RV type A/C or anything similar. For larger vehicles like hybrid vans they’d likely offer a rear higher-capacity A/C. All ductwork, fans, outside condenser(s), inside evaporator(s) drains, and so on would be designed and installed by the factory to OEM standards.

The battery pack on Accord plug-in is listed at 6.7 kWh of stored energy. For reference, that’s equivalent to just over 550 Amp-hours at 12 Volts. Even if not upsized due to larger/heavier camper needs in order to keep cost down, it would be possible to run lights, TVs, and even A/C for long periods without having to run engine to recharge batteries.

Best part, when batteries are low if camping off grid, engine/generator automatically comes on and charges batteries in minutes, not hours. Instead of a tiny 2.8 kW RV generator there is an onboard very-large generator running off a 4-cylinder engine (not exactly sure of generator capacity but would guess at least 40 kW and probably much higher). And battery pack is listed at 41 kW or 55 HP of power capacity. That much power could easily run electric stove, coffee maker, hair dryer, microwave, and air conditioner all at same time. The vehicle’s large lithium battery pack would offer almost unlimited juice if only a high-capacity inverter is added for loads other than air conditioner (vehicle A/C would already have its own power system). Actually, a large inverter option from factory for contractors to run power tools has already been done with hybrid pickups.

When camping in an RV park, plugging-in to shore power keeps battery pack charged with built-in 6.6 kW onboard charger. No need for extra components like converter or charger/inverter combo. It runs on either 220 or 120 Volt electric power and can reportedly charge battery pack in 1 or 3 hours. No doubt a 6.6 kW charger could keep up with typical camping RV loads and charge batteries overnight at same time.


I haven’t been a huge fan of plug-in hybrids because of poor payback on incremental costs, but in the case of a Class B camper I’m starting to change my mind due to endless possibilities. And also because some of the cost we spend on an RV conversion would offset a lot of the hybrid’s price premium; thereby reducing payback period. No need to duplicate generator, battery pack, converter, isolator, and so on. And the factory upgrade would improve fuel economy too. Seems like a win-win. Unless I'm missing something big.

So what do you think? Will hybrid drivetrains eventually lead to better Class Bs, or is my wishful thinking RV heresy?

[BrianW]

Admittedly I don't know much about hybrids, but my first thought is whether a hybrid will be able to deliver the kind of HP and torque necessary for commercial truck use, which are the platforms for most RVs. I doubt there will be an economic incentive for manufacturers to create platforms just for RVs.

That being said, a quick Google search turned up this interesting tidbit: that Renault just got $28 million in grants to develop a diesel-hybrid version of its Trafic commercial van (similar in style to the Chrysler/Fiat offering). Hmmm... that could be interesting and offer many of the advantages that you suggested! http://green.autoblog.com/2013/10/06/re ... brid-vans/

[carringb]

There actually was a hybrid E450 chassis produced through a partnerships with Azure Dynamics. It even had an aux HVAC unit powered directly from the battery pack. Basically, you got V10 performance out of a V8. So not at all underpowered, and it could still cruise at 75.

http://azdtec.com/techlibrary/balance/E ... 2011.5.pdf

However, when natural gas prices dropped, fleets realized they could achieve lower operating costs with natural gas then they could with a hybrid powertrain. Hybrid orders dropped, and Azure had to file for bankruptcy.


You still can install a fast-charging system however. Real Power has a PTO generator up to 15kW for the 5R110.
http://www.realacpower.com/integration.html

[Chance]

Originally Posted by BrianW

Admittedly I don't know much about hybrids, but my first thought is whether a hybrid will be able to deliver the kind of HP and torque necessary for commercial truck use, which are the platforms for most RVs. I doubt there will be an economic incentive for manufacturers to create platforms just for RVs.

.....cut.....

Like most on this forum, my interest is in smaller RVs based on one-ton vans (Class Bs), but to your concern, it shouldn't be difficult to scale up for greater power and torque. Actually, it's already being done by companies like Eaton for commercial trucks in Class 6, 7, and 8 sizes. That's equivalent to trucks like a Ford F-650 and bigger. They seem to be most popular for stop-and-go traffic like delivery and buses because the hybrid recovers motion energy to recharge batteries while braking. For over-the-highway trucks that cruise at steady speed for long periods advantages probably don't pay back as quickly if at all.

And for what it's worth, locomotives which have great power and torque commonly use a drivetrain that is similar to a series hybrid like the latest from Honda. I'm just not sure if locomotives have a clutch that connect the locomotive's engine directly to the wheels once the locomotive is up to a minimum speed the engine can work at.

For larger RVs like gasoline Class A motorhomes which are typically built on Ford F53 chassis, the hybrid components already exist. But because they are so much heavier than a Class B they would likely require a lot larger battery pack which would drive up costs for a vehicle which typically doesn't get used that much. Not like a commercial truck that may see 100,000 miles per year. And a larger battery pack wouldn't be needed to run a Class A's house power, so the greater cost is probably very difficult to justify.

By comparison, for a Class B van camper that may only weigh in the 8,000 to 10,000 pound range, the added cost of the hybrid drivetrain is largely offset by eliminating expensive components like generator, battery pack, AC, and miscellaneous battery-charging components. In my opinion the economics should be much more favorable for smaller and lighter campers like Class Bs. Plus smaller Class Bs generally get driven a lot more than larger Class As which improves system payback based on additional fuel savings.

[Chance]

Originally Posted by carringb

There actually was a hybrid E450 chassis produced through a partnerships with Azure Dynamics. It even had an aux HVAC unit powered directly from the battery pack. Basically, you got V10 performance out of a V8. So not at all underpowered, and it could still cruise at 75.

.....cut......

Thanks for links.

The Azure system looks comprehensive and shows hybrids are more complex. The Honda system doesn't seem all that different other than it's based on FWD layout and eliminates a gear-shifting transmission. The electric motor and generator are run at higher speeds to make them smaller, but the gear ratio between components is fixed. This eliminates a lot of drivetrain friction and increases MPG. Mechanically it seems a lot simpler to me than Toyota Prius or GM Volt.

Battery cost is still a major problem. The difference between Accord Hybrid and Plug-in Hybrid is around $10,000. On the other hand that isn't that much more than a diesel generator.

[chromisdesigns]

Originally Posted by Chance

And for what it's worth, locomotives which have great power and torque commonly use a drivetrain that is similar to a series hybrid like the latest from Honda. I'm just not sure if locomotives have a clutch that connect the locomotive's engine directly to the wheels once the locomotive is up to a minimum speed the engine can work at.

I believe most, if not all, modern locomotives are diesel/electric rather than series hybrids. The diesel(s) are actually generator plants that supply electric motors that drive the locomotive. There is no actual mechanical drivetrain. Generally, the control electronics can turn the gensets on and off as needed to match actual power requirements.

[Chance]

Originally Posted by chromisdesigns

I believe most, if not all, modern locomotives are diesel/electric rather than series hybrids. The diesel(s) are actually generator plants that supply electric motors that drive the locomotive. There is no actual mechanical drivetrain. Generally, the control electronics can turn the gensets on and off as needed to match actual power requirements.

Not to be argumentative, but isn’t that what a series hybrid is by definition? An engine runs a generator and a motor(s) run the wheels? Even Wikipedia lists it that way (not that that means much).

Note I intentionally stated locomotives are “similar to series hybrid” in order to avoid confusion because locomotives are not designed with typical automotive hybrid goals in mind. Their similar drivetrain is actually designed that way for reasons other than to improve fuel economy. The generator/motor arrangement mostly acts as a transmission that allows great torque to be delivered to drive wheels. So unlike hybrid cars they don’t have huge batteries to store energy and or for regenerative charging (not on a mass basis anyway). That’s why I made distinction between them and hybrid cars and possible future RVs even though drivetrain is very similar in drive arrangement.

[chromisdesigns]

Originally Posted by Chance

Not to be argumentative, but isn’t that what a series hybrid is by definition? An engine runs a generator and a motor(s) run the wheels? Even Wikipedia lists it that way (not that that means much).

Note I intentionally stated locomotives are “similar to series hybrid” in order to avoid confusion because locomotives are not designed with typical automotive hybrid goals in mind. Their similar drivetrain is actually designed that way for reasons other than to improve fuel economy. The generator/motor arrangement mostly acts as a transmission that allows great torque to be delivered to drive wheels. So unlike hybrid cars they don’t have huge batteries to store energy and or for regenerative charging (not on a mass basis anyway). That’s why I made distinction between them and hybrid cars and possible future RVs even though drivetrain is very similar in drive arrangement.

Ah, ok, maybe I misunderstood your post. Locomotives have been this way for a long time.

[E350]

"I believe most, if not all, modern locomotives are diesel/electric rather than series hybrids. The diesel(s) are actually generator plants that supply electric motors that drive the locomotive. There is no actual mechanical drivetrain. Generally, the control electronics can turn the gensets on and off as needed to match actual power requirements."

I have been looking at the GM Volt and, based on what I have read, the foregoing was how the Volt was originally envisioned: an all electric vehicle with an onboard gasoline generator. That is why the Volt is not considered a "hybrid." It is an electric car. However, they found that on long uphill grades the generator could not repower the batteries fast enough, so there is in fact a mechanical clutch mechanism which locks the drivewheels to the gasoline engine under that circumstance.

Curiously, one of the problems with the Volt and apparently all electric vehicles is not airconditioning but heat. Electric heat is so inefficient that they don't heat the air, they heat the seats and there are repeated calls for an electric steering wheel. In the 2013 model year, there is a button which allows you to "hold" the Volt in gasoline engine "on" mode just to get the extra heat from the internal combustion engine.

[Chance]

Originally Posted by E350

"I believe most, if not all, modern locomotives are diesel/electric rather than series hybrids. The diesel(s) are actually generator plants that supply electric motors that drive the locomotive. There is no actual mechanical drivetrain. Generally, the control electronics can turn the gensets on and off as needed to match actual power requirements."

I have been looking at the GM Volt and, based on what I have read, the foregoing was how the Volt was originally envisioned: an all electric vehicle with an onboard gasoline generator. That is why the Volt is not considered a "hybrid." It is an electric car. However, they found that on long uphill grades the generator could not repower the batteries fast enough, so there is in fact a mechanical clutch mechanism which locks the drivewheels to the gasoline engine under that circumstance.

Curiously, one of the problems with the Volt and apparently all electric vehicles is not airconditioning but heat. Electric heat is so inefficient that they don't heat the air, they heat the seats and there are repeated calls for an electric steering wheel. In the 2013 model year, there is a button which allows you to "hold" the Volt in gasoline engine "on" mode just to get the extra heat from the internal combustion engine.

Not that it should matter much what it's called or classified as, but I recall GM got a lot of negative press over the subject of whether the Volt should be called an Electric car, or more accurately a plug-in hybrid.

http://www.businessweek.com/autos/autob ... cares.html

In my opinion the Volt's drivetrain is not as simple as the new Accord's, plus the Volt's engine is a lot smaller. I'd be surprised if the new Accord Hybrid can't hold speed on long Interstate grades. It has a lot of power both from the electric motor and internal combustion engine. Reported acceleration data suggest it's as fast from 0 to 60 as a regular Accord. It's actually quick for a hybrid. Obviously a Volt can drive in all-electric mode much farther due to larger battery pack.


By the way, good point on heat issue. Maybe a heat pump would work for milder climates. For colder camping the engine would just have to start and recharge the battery pack more often. I'd roughly guess maybe twice during a cold night based on my electric heater's size. A well insulated van should stay comfortable with about a 1500 watt heater. Battery pack should run that at least 3 hours. Probably a lot more.

Unless I was going to be camping in very cold weather on a regular basis, I think I'd delete the propane system and go all electric to keep the van simpler.