Chevrolet Volt

[Magiver]

Another explanation.

If I understand it correctly, both cars use an ICE and 2 electric motors (one doubles as a generator). The difference is that the Prius connects all 3 motors to the 3 different elements of a planetary gear system and the Volt ties them to 2 of the elements along with 3 clutches to couple and uncouple the the ICE from the generator/motor and also to lock gear system so only the 149 hp motor drives the wheels.

[DSeid]

If you read your own cites you’d find your understanding to be wrong and this Magiver. The ICE never directly powers the car, at higher speeds it bypasses the battery and supplies electricity directly to the electric traction motor:

Once the speed climbs to about 70 mph, the motor/generator again couples to the ring gear but now—in “charge-sustaining” mode—the smaller electric motor is also affixed to the running gas engine. … there are a few things to keep in mind. The first is that the car can’t move solely on the gas engine—if the main electric motor quits, the car will be stranded. Secondly, the engine routes its power through the motor/generator.

In any case, the Volt’s technology defines its own new category, a combination of EV and hybrid that defies conventional definition. And as we’ve experienced, it works.

It is not quite an EREV but it is not a hyped up Prius with a bigger battery either. I am a much bigger fan of the simplicity, the fewer moving parts, of pure BEVs. But your insistent dismissiveness of the technology as nothing new or different is contradicted even by your own cite, which says it “defines its own new category” - so give that bit up already.

[xenophon41]

@DSeid

If you read your own cites you’d find your understanding to be wrong and this Magiver. The ICE never directly powers the car, at higher speeds it bypasses the battery and supplies electricity directly to the electric traction motor…

DSeid, the ICE can only supply mechanical power, not electrical. It turns a crankshaft, which is connected via a clutch to the smaller motor/generator. When the battery charge is low, the ICE is connected to the motor/generator to generate power to charge the battery.

At no point is the motor/generator used to provide electrical power to the main drive motor. In generator mode, it charges the battery, and in motor mode it draws electrical power from the battery and provides mechanical power to aid the main drive motor. When the ICE is engaged, it’s either turning the m/g as a generator to charge the battery (determined by charge level) or it’s adding power through the m/g as a motor to drive the vehicle (determined by vehicle speed).

So at times the ICE is indeed providing power to move the vehicle, but it’s never doing the job by itself. -But I don’t think Magiver ever said it did.

[DSeid]

What Magiver is claiming is that it is exactly the same as a Prius but with more emphasis on the battery. That is just not true. No matter how many times he says “Yes it is”. It also is not a pure EV, something that has bothered some purists. It really is in a different category, neither fish nor foul. For better or worse.

[Lobohan]

@DSeid

What Magiver is claiming is that it is exactly the same as a Prius but with more emphasis on the battery. That is just not true. No matter how many times he says “Yes it is”. It also is not a pure EV, something that has bothered some purists. It really is in a different category, neither fish nor foul. For better or worse.

Magiver argued for ten plus pages against the laws of physics in the “can you punch out a monkey thread”. He isn’t going to admit he’s wrong.

[xenophon41]

@DSeid

What Magiver is claiming is that it is exactly the same as a Prius but with more emphasis on the battery. That is just not true. No matter how many times he says “Yes it is”. It also is not a pure EV, something that has bothered some purists. It really is in a different category, neither fish nor foul. For better or worse.

Essentially, the Prius is a parallel hybrid, and the Volt is a mostly serial hybrid that’s sometimes a parallel hybrid. The main distinction is that one can drive the Volt in all situations without ever using the combustion of gasoline for direct propulsion, and I agree that’s an important distinction.

GM needed to deliver a car with 70+ mph capability for the US market, so they very cleverly designed in the capability to use the ICE to assist the EM, but that’s clearly not the dominant feature of the vehicle.

[Magiver]

@DSeid

If you read your own cites you’d find your understanding to be wrong and this Magiver. The ICE never directly powers the car, at higher speeds it bypasses the battery and supplies electricity directly to the electric traction motor.

If you look at the video you’ll see that the ICE is clutched to generator which at higher speeds is used like the planetary gear system is used in the Prius to multiply the gearing of the main electrical motor. In the lower speeds, only one of the 3 gears of the planetary gear set is unlocked and that is driven by the electrical motor. At higher speeds a 2nd set of gears are unlocked and generator is used. when the battery is low the engine is clutched to the generator directly.

The difference between the Volt and the Prius is that the Prius uses a mixture of all 3 motors and all 3 gears continuously.

Here is the [:
-The ICE is connected to the planetary set
-The generator is connected to the sun gear
-The electric motor is connected to the ring gear which drives the wheels

[URL=“Toyota Prius - Power Split Device”]Here](http://www.google.com/imgres?imgurl=http://www.familycar.com/RoadTests/ToyotaPrius/Images/THS-Diagram.jpg&imgrefurl=http://www.familycar.com/classroom/alternativepowersystems.htm&h=470&w=500&sz=31&tbnid=WH5Kiqpdj_U2XM:&tbnh=122&tbnw=130&prev=/images%3Fq%3Dprius%2Btransmission&zoom=1&q=prius+transmission&usg=__TV5CsKODVMaxkI9umkBmtJbu1MQ=&sa=X&ei=R3jpTNnzJpTtngfF-e33DA&ved=0CCoQ9QEwBQ)is an interactive that shows how the 3 motors interact. You can move the levers changing each motor to see what happens.

The volt uses the same 3 motor setup along with a planetary gear but they don’t mix all 3 gear sets. The 4 modes work as follows:

1. EV mode for low speed (up to 70 mph): only the main motor is engaged, so all power comes from the 149hp motor;

2. EV mode for high speed (up to 100 mph): both motors are engaged to provide power. The combined output is still regulated at 149hp, but running two motors at lower rev is more energy efficient than running only the main motor at high rev;

3. Range extending mode for low speed (up to 70 mph): when battery runs low, the engine starts working. It drives the auxiliary motor, which now acts as generator and is decoupled from the gearset, to generate electricity and supply the main traction motor. As a result, the car is powered by the main motor. Of course, the 84hp engine cannot generate enough power to realize the main motor’s 149hp output, so this mode works at below 70 mph. However, in case of overtaking or ascending, the combination of engine power and battery reserve may still allow short burst of full power;

4. Range extending mode for high speed (up to 100 mph): all clutches are engaged. This mean the engine is mechanically connected to the gearset via the auxiliary motor. The latter still works as generator to supply the main traction motor. However, the majority output now comes from the engine. Again, momentary release of full power is possible from the combination of engine and battery power. For extended exploit, output should be no more than the engine’s 84hp. Still, this is enough to keep up with traffic on highway.

[Magiver]

Prius diagram that missed the edit.

[Magiver]

Here is a link to a downloadable word document:

Opel | Stellantis

This shows that the Volt’s main motor is tied to the sun gear and the ring gear is either locked out for low speed use or the generator/motor is connected to it to work in tandem for higher speeds. At sustained higher speeds the ICE is clutched to the generator/motor.

It is as I said before, the Volt only ties 2 of the 3 gears to any of the motors where the Prius ties each of the 3 motors to one of the three gears. It is not efficient for the Volt to use the main motor exclusively at higher speeds because they loose efficiency so they tie the 2nd motor into the planetary set to lower the RPM range of the primary motor. The ICE is coupled to the smaller motor when the battery is depleted at higher speeds.

[Try2B_Comprehensive]

I see. Ignorance fought. Its still more ev than a Prius though.

[Magiver]

@Try2B_Comprehensive

I see. Ignorance fought. Its still more ev than a Prius though.

Yes, it is absolutely more EV than Prius. My point is that from a production (investment) point of view it is the reconfiguration of the basic Prius concept with more batteries added. The batteries cost more so it’s less affordable than other hybrids.

IMHO GM should have waited for the cost of batteries to come down and concentrated on building a name for their other hybrids. They should also have used a standard Atkinson 4 cycle ICE engine instead of the premium fueled motor they’re launching the car with. They will replace this in 2012 or 2013 but WTH? Why not put the standard hybrid ICE type engine in now?

[DSeid]

The concept, one I know you disagree with, is the same as was for regular hybrids. Prices don’t come down until you have volume production. You don’t get volume production until the price to the consumers allows for some volume purchasing. The idea is that most analysts believe that at gas prices where they are to slightly higher EVs become cost competitive at a battery cost of $250/kWh and that they can get there with volume production and not without volume production. So you subsidize the initial lower volume period; then it either flies on its own or sinks.

As to why they chose the particular ICE they did -

per Nitz, “the 1.4L NA four has better brake-specific fuel consumption than the 1.0L turbo when used in steady state mode, as it will be in the Volt application.”
Also Nitz claims the four cylinder engine will provide for a smoother transition from EV to range extension saying “the objective is to keep the engine off and when the engine comes on, you don’t want to know it’s on. You want it really smooth and four cylinder is smoother than a three.”
Nitz also noted that the four cylinder has a lower cost and that when the turbocharging architecture is added to the 3-cylinder engine, the non-turbo four cylinder engine setup is actually lighter.

And why premium?

According to Volt vehicle line director Tony Posawatz, there are two main reasons.
“The Volt is all about efficiency,” he said. “Premium fuel offers the opportunity to have a little bit more spark.”
“Ninety one octane fuel also offers the opportunity to be a little more efficient, he added. “So technically its a five to ten percent fuel economy improvement the few times that most people will run the range extender.”
Posawatz also claimed the increase is cost will be offset by the efficiency gains.
“Based on our calculations the fuel economy and efficiency gains you get will effectively compensate for the extra cost of premium fuel,” he said
Additionally, premium fuel is apparently slower to go stale.
If people are not using the extended range capability a lot, the premium fuel does last a little longer,” he said

My guess is that the last bit is the more key factor. There are going to be quite a few people who literally will only use the car as a commuter less than 40 miles a day; gas going stale with any frequency would end up being a great sales pitch for the pure BEV approach.

[Magiver]

@DSeid

The concept, one I know you disagree with, is the same as was for regular hybrids. Prices don’t come down until you have volume production.

It will ALWAYS be more expensive then a regular hybrid. ALWAYS. However, when prices come down with batteries it won’t be a tax-payer funded waste of space. Since they really didn’t invent anything new with this car it was a pointless exercise.

@DSeid

You don’t get volume production until the price to the consumers allows for some volume purchasing.

That has nothing to do with the price of tea in china. The extra cost of the Volt is clearly in the batteries.

Battery technology will progress whether they build this car or not because there is a huge market for more efficient batteries in millions of products already on the market.

@DSeid

As to why they chose the particular ICE they did -
And why premium?My guess is that the last bit is the more key factor. There are going to be quite a few people who literally will only use the car as a commuter less than 40 miles a day; gas going stale with any frequency would end up being a great sales pitch for the pure BEV approach.

That is just marketing psychobabble. They are already planning on replacing the engine to an E85 fueled one in 2013. It just wasn’t ready in time.

[DSeid]

Total cost of ownership will not necessarily always be more than a regular hybrid. That depends on the cost of the battery, the cost of gas, the cost of electricity, the difference in the cost of other maintenance between the two sorts of vehicles, and the longevity of each vehicle. Bottom line is that the lines cross as the price of gas goes up and the price of batteries goes down.

The power batteries used in these vehicles have few other volume markets than EVs. Oh a few, grid stabilization comes to mind, but EVs are really the driver for this sort of battery production. Costs go down more than anything else by having highly large automated lines being fully utilized. Costs are highest when they are produced in small batches or when a company has invested in a large production line but is not yet utilizing hardly any of its capacity.

And as for the E85 plans, IMHO the E85 talk is the marketing babble. GM has put a lot into flexfuel and had initially stated that the Volt would be E85 capable. They cannot publicly back away from it now, not in their new car of the future. But it won’t be “ready in time” for 2013 either. My understanding is that E85 goes stale much faster, and that will make a no go product for this purpose. Now a small cheap diesel engine as an extender …

[Magiver]

@DSeid

Total cost of ownership will not necessarily always be more than a regular hybrid. That depends on the cost of the battery, the cost of gas, the cost of electricity, the difference in the cost of other maintenance between the two sorts of vehicles, and the longevity of each vehicle. Bottom line is that the lines cross as the price of gas goes up and the price of batteries goes down.

Who would have thought there was a break-even point between an EV and a Hybrid car? I’ve only been talking about costs the whole thread and why GM should have waited for the cost of batteries to come down :dubious:

@DSeid

And as for the E85 plans, IMHO the E85 talk is the marketing babble. GM has put a lot into flexfuel and had initially stated that the Volt would be E85 capable. They cannot publicly back away from it now, not in their new car of the future. But it won’t be “ready in time” for 2013 either. My understanding is that E85 goes stale much faster, and that will make a no go product for this purpose. Now a small cheap diesel engine as an extender …

30 years of owning lawn mowers and snow blowers and they’ve started right up for me each season with “stale” fuel. The fresh fuel hyperbole response sounds better then “we pulled a motor out of our ass to knock this thing out in time”.

[DSeid]

The Straight Dope on stale gas.

What makes gas go stale? Usually the first thing that happens is the lighter chemicals in it evaporate, leaving behind a heavier, less peppy product. Gasoline is an ideal motor vehicle fuel partly because it vaporizes readily to form a combustible mix with air. If it sits unused, however, its more volatile components waft away, leading to poorer engine performance. It’s hard to tell how much punch your gas has lost without scientific testing, but don’t worry — though your car might start a little harder, it’ll still run (assuming it ran before), and there’s little risk in burning the fuel if this is all that’s gone wrong.

The second cause of bad gas is oxidation — some of the hydrocarbons in the fuel react with oxygen to produce new compounds, almost all of them worse than what you started with. When oxidation becomes a problem, you’ll know it without lab tests — the gasoline gives off a sour odor. If you pour some into a glass container, you’ll see it’s turned dark, and you might find small, solid particles of gum. Using oxidized gasoline is a bad idea, since the gum can clog your fuel filter, create deposits in your fuel system (especially the injectors), and generally hurt performance.

Finally there’s the problem of contamination. Water, which can cause gas-line freezing and other problems, is the main culprit — it usually gets into stored gas via condensation as temperatures fluctuate. If the gas is relatively fresh, a “fuel dryer” additive (basically isopropyl alcohol) can help by combining with the water to make a burnable mix that can be run through the system. Another potential problem caused by water is bacteria, although that’s not nearly as common. Gas contaminated with dirt or rust is a no go, as the crud will foul your engine.

The push for reformulated gasoline using ethanol (such as E10, aka gasohol) has heightened concerns about gasoline stability. On its Web site Chevron claims “federal and California reformulated gasolines will survive storage as well or better than conventional gasoline,” and I can’t find any good test data to dispute that. The fact remains that ethanol is hydrophilic, meaning it tends to draw moisture out of the air, so theoretically gasohol should become contaminated more easily than pure gasoline.

The shelf life of gasohol is difficult to determine — proponents claim it’s similar to that of pure gasoline but present no hard data. Anecdotally speaking, boat owners and survivalists — people who often deal with stored gasoline — report a much shorter shelf life for gasoline-ethanol blends and advise against storing them long-term.

FWIW, and Cece is no final word, but given that gas might sit in that tank unused for over a year, I’d be not so fast to dismiss the concern as pure “hyperbole”.

[Magiver]

@DSeid

The Straight Dope on stale gas.FWIW, and Cece is no final word, but given that gas might sit in that tank unused for over a year, I’d be not so fast to dismiss the concern as pure “hyperbole”.

You forget the fact that they didn’t use the more efficient atkinson cycle engine and plan on replacing the current one in a couple of years.

[DSeid]

I certainly have not forgotten that they intend on improving the range extending generator choice. No doubt they went with what they already had in production for the first generation. I do not pretend to know the advantages or disadvantage of the atkinson cycle … but somehow doubt that you know more about it than the GM engineers do. I merely posted the rationale of premium and why E85 seems unlikely future choice despite GM’s press releases. Seriously a small diesel would make more sense. But who knows?

Tony Posawatz, the Volt Line Director at GM, admits that they didn’t initially spend a lot of resources on the extended-range feature of the first generation Volt, but says, "You can bet that we are already looking at advanced projects on what an extended-range feature should operate like in the belief that this propulsion system will resonate with customers. That may be a Stirling cycle engine, perhaps it’s a Wankel, a gas turbine, a small displacement motorcycle engine– you can extend the possibilities to a lot of different alternatives.”

[Magiver]

@DSeid

I certainly have not forgotten that they intend on improving the range extending generator choice. No doubt they went with what they already had in production for the first generation. I do not pretend to know the advantages or disadvantage of the atkinson cycle … but somehow doubt that you know more about it than the GM engineers do. I merely posted the rationale of premium and why E85 seems unlikely future choice despite GM’s press releases. Seriously a small diesel would make more sense. But who knows?

No a small diesel would not make more sense. It costs more to make a diesel which drives the price of the car up. And stop posting GM drivel. They hemmed and hawed 12 ways to Sunday to avoid admitting the ICE had a direct connection to the drive train.

[DSeid]

You are right.: quoting the people close to the decision process and in charge of the program about what their thoughts were and what their plans might be is a silly thing to do when trying to find out what their thoughts were and what their plans might be.

The example cited as a small diesel was a Wankel engine, such as the 20 kW one used in a FEV/LiiON converted Fiat 500. A good discusion of the potential reasons to consider the choice is found here. The disadvantage is that another engine choice would possibly be more fuel efficient. (This one is pulling off 60 mpg in charge sustaining mode, but in a small car with not so great acceleration.) OTOH, the engine would be smaller and lighter than most other choices, the use of diesel would allow for a smaller tank that allows the same range (also saving size and weight), and it has superior noise/vibration/harshness characteristics. I have no personal knowledge regarding likely cost in volume production or of the needed pollution control features. Other companies experimenting with Wankels for this purpose include Chery and Audi. I am glad that you apparently have more knowledge about these issues than do the professional automotive engineers who are working for companies like GM and will, of course, defer to your expertise over the thoughts and analyses … oh I mean “drivel” … of those experts. They shouldn’t even bother researching the possibilities when they could save time and just consult you!