By on November 24, 2009

Is anyone else seeing GM's business plans in this chart? (courtesy:gm-volt.com)

As we saw in the last VBW, the Volt’s range-extender still needs some software work. But efforts to to keep the gas engine from acting like a thrashing, disembodied dervish will have to balance the desire for smooth operation and maximum efficiency.  And it’s looking like efficiency in charge sustaining (CS) mode won’t match the hybrid standard-setters. Volt chief powertrain engineer Alex Cattelan breaks the news gently to the true believers at GM-volt.com

You’ve got to understand that all of the decisions that we’ve made around this product are made because its an EV. That is the first and foremost thing that it needs to be. So because it is an EV some of the decisions that we’ve made around engine operation will be different than what Toyota makes in its parallel hybrid. For them they are always operating in hybrid mode so they need to optimize everything for engine operation.

In our case we’re optimizing everything for EV operation and the secondary is certainly going to be better than conventional vehicles, but were not necessarily totally optimizing the system for charge sustaining mode because we don’t want to compromise electric vehicle mode.

Cattelan goes on to describe the sophistication of the Volt’s constantly-updating efficiency software, sourced from the abortive Two-Mode hybrid system. And as the chart above shows, the plan for charge-sustaining mode is an interesting one. Essentially, it involves keeping the battery state of charge between 30 and 35 percent, once the 40 miles of (estimated) EV range is tapped. Which is a fine idea as long as the engine on-off improves. Otherwise, drivers might just find themselves nervously counting down the five percent charge range before the 1.4 liter range extender thrashes to life again. Hoping for an answer to that question, Gm-volt notes “I’ve driven the 2-mode and notice you can see the switched in mode of operation without feeling it in the car.” Cattelan’s response reveals the trade-off that’s in play:

Which is the goal, you don’t want you to feel it in the car, we don’t want the customer to know these transitions are taking place, but we need to be able to enable them for efficiency.

Later, when Cattelan has explained the efficiency benefits of having a range-extending engine that’s independent of the drive axle, Gm-volt pushes again on the charge sustaining-mode efficiency question, saying “It seems to me then you should make CS mode even more efficient then in a car where the engine always has to turn the axle?” Cattelan’s answer once again downplays the notion, saying

Right and it is more efficient than a conventional vehicle because they do have to have that engine coupled. Again were optimizing some of those efficiency point puts we are really doing is focusing on the optimization of the EV. There are trade offs because we absolutely consider this product an EV by nature.

It’s not a hybrid! We’re focusing on EV mode! More efficient than a “conventional vehicle” in CS mode! Which means, what, 35 MPG? As Paul Niedermeyer explained some 18 months ago, the Volt is going to have a hell of a time beating the Prius on a mass-market basis. Which is what happens when you come up with the marketing line (“40 miles without burning a drop of gasoline”) before you develop the car.

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55 Comments on “Volt Birth Watch 174: Enough With The Prius Comparisons!...”


  • avatar
    superbadd75

    Why can’t they just insulate the hell out of the engine compartment? And wouldn’t a clean diesel work a lot better than a thrashy gasoline 4? This Volt thing is put together about as well as one would expect from GM, and that doesn’t bode very well for its future.

  • avatar
    Lexingtonian

    I hate to say it, but I tend to agree with the GM fellow here.
     
    The point of the car isn’t the mileage in hybrid mode, it’s that it has a hybrid mode in addition to the EV mode.

  • avatar
    reclusive_in_nature

    Just want to be the first poster (at least I hope I am) to say these two words: Climate Gate!

  • avatar
    Dave Skinner

    Looking at the right hand side of the chart, how does the “charge mode” charge the battery before the car arrives at “Parking” (not a mode, by the way)?

    Since the chart is broken out into three colored sections, some might get the impression that the “charge” mode occurs while the car is being driven. Especially since the Charge Mode description makes no mention of the car being parked.

    I guess the chart designers decided that “Parking” only occurs after the battery is fully charged. This despite the fact that the car has to be PARKED to charge…

  • avatar
    srogers

    I’m in agreement with Lexingtonian, if you want a hybrid, buy a hybrid.
    Not to say that I have any intention of buying a Volt, but both my spouse and I could likely go a couple weeks at a time without ever going into generation mode. Not everybody has a 80km commute or spends weekends out of town.

    • 0 avatar
      JLD2k3

      That’s what I’m thinking as well.  I drive ~30 miles each day and the wife even less.  If we go out of town, we’ve got either of our existing cars and would leave the Volt in the garage.

    • 0 avatar
      Quentin

      More of a reply to JLD2k3 — why not just get an EV instead?  Isn’t the gasoline engine and massive alternator just dead weight if you aren’t going to utilize the extended range?  I could see my household having an EV as my wife’s commuter (20  mi round trip to work, 3 days per week) and myself taking the EV on the days she doesn’t work (2 to 4 days/week @ 12 miles round trip). 

  • avatar
    Daanii2

    The Chevy Volt is like GM’s Impact — very much a first-generation car. Expectations for it have been built too high. It will disappoint. The second-generation will be better, but probably will not have a chance. The failure of the first generation having killed interest in the concept.

    I’d like to have seen GM develop its AUTOnomy, or Hy-wire, concept car. Get rid of the hydrogen fuel cell, replace it with a battery pack and generator, and what have you got? A new approach with lots of promise.

    The Chevy Volt is just the same old same old. Nothing new here that Henri Piper did not patent 100 years ago.

    • 0 avatar
      Steven02

      I am confused by your statements of get rid of the fuel cell and replace it with a battery pack and generator and that is a better approach.  What is the Volt again?
      While, it isn’t the skateboard chassis, it is a big new approach.  And what expectations do you not expect it to meet?  Why don’t you think there will be a second generation car?  You are killing it before it even see a show room.

  • avatar
    Daanii2

    Just looked more carefully at that graph. In the middle “Extended Range Mode,” GM does show the Volt’s battery being charged by the generator.

    Could that be correct? Did GM change the way the generator works? GM people have said, specifically and repeatedly, that the generator will not recharge the batteries. Now this.

    • 0 avatar
      thalter

      I would guess that it is being recharged by regenerative braking, and not the engine.

    • 0 avatar
      Greg Locock

      That graph is consistent with GM’s explanation of the Volt’s strategy. It is not consistent with the descriptions put about by various clueless commentators. GM released a paper a couple of years back outlining the strategy and nothing much has changed since.

    • 0 avatar
      John Horner

      The battery is going to be recharged by the gen-set, a little! What GM has been trying to say is that the software isn’t going to allow the gen-set to completely recharge the batteries because doing so would make the next suckling of the electrical socket in your home pointless. If they are going to start and stop the gen-set repeatedly then sometimes it will be charging the battery pack.

  • avatar
    jjdaddyo

    I’m not sure I understand the hate for this car. Sure it’s market is limited- so’s the market for Chevy Suburbans.
    The idea here is that this is an EV that won’t leave you with a dead battery on the side of the road, with which you can do 90% of your driving without running the engine, and you won’t have to think twice about making a 80 mile trip.
    The idea is to keep the cost and the negative mileage impact (i.e. extra weight) of the engine to a minimum, so a diesel won’t do it. The fine tuning is going to come in the software (as discussed) and in tweaking the engine so that it charges the battery to a sufficient level while using as little gas as possible doing it.
    This is a first generation car, with a whole new set of engineering problems. The first gen Prius was pretty rough, and I hope GM has a chance to get to the gen 3 Volt also.

  • avatar
    KixStart

    jjdaddyo: “I’m not sure I understand the hate for this car. Sure it’s market is limited- so’s the market for Chevy Suburbans.”

    It’s not hate, it’s disgust.  GM is spending beacoup bucks to build a vehicle that won’t sell.  Don’t think “Chevy Suburbans;” think, “Chevy Tahoe Hybrid.”  The
    market for Suburbans is limited.  The market for the Tahoe Hybrid is nonexistent.

    Daanii2: “Could that be correct? Did GM change the way the generator works? GM people have said, specifically and repeatedly, that the generator will not recharge the batteries. Now this.”

    It charges it just a little bit, to get on-going power.  It doesn’t come anywhere close to fully recharging it.  There is continuing confusion about the Volt program because too many GM execs know too little yet say too much.  The gas engine is small, so the car must have some reserve battery power all the time for performance reasons, or you’d be driving a ~70hp 3400lb car when the battery is depleted.  The performance of that lashup would be sort of bad, to say the least.

    Lexingtonian: “The point of the car isn’t the mileage in hybrid mode, it’s that it has a hybrid mode in addition to the EV mode.

    Except that people will want to draw a cost/benefit comparisons to the Prius and 0ther cars.  In such comparisons, the Volt suffers greatly because of high up-front cost.  Still, some look at the benefit as fuel use avoided and won’t worry too much about the cost.  Still, if the charge-sustaining mode mileage is poor enough, there will be few where the Volt saves fuel vs a hybrid – or even a decent economy car.

    The way we use our principal car, unless the Volt gets something like 45mpg in charge-sustaining mode, we’d use less fuel every year with a Prius.  We either take very short trips or very long ones.  On very short trips, a Prius doesn’t use much gas.  On the long ones, a 50mpg Prius will use less gas than a 40mile AER/35mpg Volt.

    • 0 avatar
      charly

      The problem is not the market. There is a market for the volt. It just isn’t in the USA at the moment but in Japan and Europe where it will outsell the Suburban every month after its market introduction.

  • avatar
    KixStart

    Daanii2,

    I think further confusion comes from GM’s failure to represent the “Charge” area on that graph as “parked.”  It will be parked in that green zone.

  • avatar
    Daanii2

    KixStart,

    Looking at the original article on GM-Volt.com, I finally figured out what they mean by “Parking.” They mean the car is sitting, but not charging.

    In this whole interview with Alex Cattelan, she says nothing of substance. Just hides the ball. I’d hoped GM would tell us more. This is disappointing.

  • avatar

    In the Volt’s sweet spot (total usage per day of less than 40 miles — the average US commute is 16 miles), using a whole lot of US averages (and beware of averages when used to model reality), the Volt beats the Prius on an energy cost per mile basis.
    Using data from here: avt.inel.gov/pdf/fsev/costs.pdf – (I have seen similar calculations elsewhere):
    Assuming a 4 mile/kWh rate (this is an unknown for the Volt right now, but again, this is an EV average, and about what the Prius gets on batteries only) and a cost per kWh of $0.09 (this varies widely in the US but is a decent guess- my power bill is around here, coincidentally) the Volt has an energy cost per mile of $0.02/mile.
    A car that gets 45 mpg with gas @ $2.60/ gal costs about $0.05/mile.
    Granted, there are so many variables left out of this  it is almost nonsensical for a car to car comparison, but as far as energy costs go (and most people compare mileage to mileage anyway) this will give you a picture.
    As for what the Volt’s mileage will be calculated at when running on the generator, that’s anyone’s guess at this point. But I would be willing to bet that a Volt would beat 50 mpg out to at least 100 miles, starting from a full charge.

    • 0 avatar
      John Horner

      Here in Nor. Cal., home to a lot of potential Volt buyers, our electricity costs more the more you use. Think progressive income tax, but applied to your electric bill. Consequently, my marginal cost for additional kWhs is over 35 cents each! For people in this situation, the Volt would cost more to fuel up than would a Prius.

  • avatar
    Spike_in_Irvine

    I am intrigued by the comments from Superbadd75 and jjdaddyo about diesels. A diesel engine develops its torque at low revs which would avoid the “thrashing”, also it is normally more efficient, especially at constant revs. The negative alluded to is the weight. Can any of our readers do the math on a comparable torque engine for weight comparison? I wonder if a diesel was not considered because it would be perceived in the U.S. market as another negative aspect. Maybe the Vauxhall version in Europe could use a diesel engine and a hatchback body. It would certainly make an interesting comparison.

    • 0 avatar

      I was taking a diesel out of the equation based on the fact that everything I have read says that for equivalent gas/diesel engines the diesel will be more expensive to produce. Add to that US consumers preferring gas to diesel at this point, not to mention GM having no small, efficient diesel to put in this car, and the Volt will definitely be gas powered for the foreseeable future.

    • 0 avatar
      PeteMoran

      @ Spike_in_Irvine and @ jjdaddyo
       
      Weight is likely the only consideration, ruling it out as extra mass to accelerate while in EV mode. It’s the same reason they won’t appear in hybrids. For the weight difference, you could put a few more kWhr of battery and have a greater gain.

  • avatar
    PeteMoran

    What do you get when a company with dinosaur thinking sees fuel efficiency rising to near the top of purchasing decision making and their hybrid attempts are woeful? They try a desperate attempt to differentiate themselves with a new and (claimed-to-be) innovative alternative regardless of the technical merit or problems.
     
    Meanwhile a company like Ford has purchased/developed hybrid and is moving forward with it. Hyundai soon too.

  • avatar
    T2


    Spike – The problem using diesels is incompatibility with fixed (magnetic) field generators. This generator requires maximum torque input all the way up the power/rpm curve. Modern gasoline engines can provide that. The generator can then provide max current at all times. A diesel engine, in comparison, has a torque peak at 2800rpm beyond which it decays until reaching maximum power.
    On one particular turbodiesel I investigated, I found that the torque at the top speed of 4200rpm was down 33%. This means that the demand for generated current must be reduced by 33% if you are not to stall out the engine. The repercussion for the electrical side of the equation means the copper loading of the generator, or ampacity as we call it, will be only 67% utilised at the very point we need it most, which is at maximum rpm. The generator is still usable for maximum power but we are taking a risk that the peak current that could be generated by the higher available maximum torque down at 2800rpm is capable of seriously overheating the stator winding. Of course the prudent designer will probably size up the generator by 33% to avoid this issue or limit the diesel engine torque and demand the diesel to run at a higher rpm in order to compensate. The latter solution has the penalty of increased frictional losses while the former, involving a 33% generator frame size upgrade, has the obvious drawback in both increasing cost and weight.

    • 0 avatar
      PeteMoran

      @ T2
       
      What are you on about? Engine power is power regardless of diesel or gasoline combustion. The generator would be matched accordingly. I’m not sure why you’re trying to work torque into consideration.
       
      The consideration for a mobile application is then weight only.

    • 0 avatar
      Spike_in_Irvine

      Since the point of the ‘Volt’ is to disconnect the engine from the wheels, why does it have to work over any great range of revs. It should operate at the optimum speed for the generator. If, asT2 suggests, this is a higher speed than the diesel engine would be comfortable at, then we introduce gearing. Generators in RVs for example will work harder and louder as load is applied but they do not go faster. I think this is the problem with the prototype during the charge sustaining stage. It sounds disconcerting because it is either running at generator speeds (thrashing) or it is idling

  • avatar
    John Horner

    It sounds like what Alex Cattelan is saying is that they don’t want to let the on-board gen-set run long enough to fully recharge the battery because doing so would mean the vehicle wouldn’t take much of a charge the next time it gets to an electrical socket. It would be much smarter to have the vehicle’s charge management system be aware of the intended trip and to then take that into account in its charge management algorithm. An easy way to do this would be to include a Garmin like GPS in every vehicle (which you can buy retail now for under $200!). As long as the driver inputs the intended destination the vehicle computer would know everything it needs to know about the planned trip.  With that information, the software could do a MUCH better job optimizing overall efficiency than if the car is just running dumb and blind.
    Assuming GM isn’t smart enough to use my GPS idea, what is going to happen when you drive this thing up and down the large mountain ranges of the American West with a full load of passengers and luggage on board? People who have spent their lives around Michigan might not understand the energy demands of such conditions. Is the Volt going to slow down to vintage VW Bus speeds under certain demanding circumstances? No matter how you get the power to the wheels, the seventy odd horsepower maximum of the onboard gen-set is not going to give very good performance through the Rockies or the Sierras.
    Cattelan sounds like an engineer who is optimizing a product against an imagined set of criteria without having real contact with how the product is going to end up being used. His pontificating about the sanctity of the Volts “EV-ness” is a bad sign.

  • avatar
    gslippy

    The Volt is a plug-in locomotive downscaled to passenger vehicle size.

    Only technogeeks will appreciate the unusual performance, sounds, price, and care associated with this car.  The mainstream buying public will spurn it, in spite of GM building cars “Americans want to buy”, as the government says.

    The truth about cars is that most drivers want to put fuel in them and drive them 200-300 miles.  The Volt requires two fuels to do this, plus an expensive charging station. 

    What happens when the customer never plugs it in? Interestingly, Edmunds is reporting that a long (230 miles) trip would yield about 38.3 MPG: http://www.edmunds.com/chevrolet/volt/2011/testdrive.html. That’s not worth $40k to most buyers.

  • avatar
    T2


    Seems that the formatting disappeared from my previous post. Despite that I hope I offended no one by my disdain for diesels.
    - PeteMoran,
    It is important that for the smallest engine / generator combo that the torque curves match so that the whole assembly can rotate at the lowest speed possible for a given power output.
    As I commented earlier the generator should not be able to stall the engine for engine speeds exceeding 2400rpm due to a declining engine torque characteristic with speed above that point.
    Unfortunately that is the case with the diesel. As with some unfamiliar concepts I can explain it for you as best I can, but I can’t understand it for you.
    Next up. Yes , let’s stop this comparo with the Prius. We are dealing with tigers and lions here. Simply put the Prius has a battery for power while the Volt has a battery for energy. Two entirely different philosophies. The Prius leans towards the advantage of the electric transmission while the Volt leans towards the advantage of the pure electric vehicle.
    I like to think that TTAC gives us the wing’ed flight whereby we can branch out and perchance discover and learn new ideas. However as of now, more often than not, TTAC finds us with that birdlike penchant – for hanging out on the dumpster behind the Safeway’s. That said I would like to conclude by saying that there is a group of us that are agin’ the current hybrid technology with its exotic “boutique energy” sources but still find favour with the idea of the electric transmission as a future direction for vehicle powertrains.

  • avatar
    PeteMoran

    Maybe I’m missing something, but why are you mentioning an RPM figure?

  • avatar
    Brock_Landers

    One of the major issues with using diesels in a hybrid powertrain is diesel engine startup and shutdown. Modern diesels have become very smooth and quiet while they are running, but starting and shutting them down still creates lot more noise and vibration than conventional gasoline engine. Gen3 and even gen2 Prius driver doesn’t really notice the continuous transition with gasoline engine startups and shutdowns. With diesel engine this continuous transition would become very noticeable and annoying. Also diesel ignition method is different from gasoline engine. Even the most modern direct injection diesels use glow plugs for pre-heating, and even with a warm engine the startup happens with a small delay (approx 1-2 sec, longer for a cold engine). Combining this with continous startup-shutdown nature of a hybrid drivetrain and making it pleasing to drive and durable for the end consumer is difficult.
    PS! And third reason is ofcourse in turbocharging. Turbocharged engines are not with linear poweband, so it is more difficult to make them smoothly work together with electric engine.

  • avatar
    Carlson Fan

    “The point of the car isn’t the mileage in hybrid mode, it’s that it has a hybrid mode in addition to the EV mode”

    Right on! As stated in the article this vehicle is being designed as an EV. The back-up generator is only there for one reason,  to keep you from being stranded on the side of the road with a depleted battery pack. With my current driving habits I could easily drive the Volt all year and never fired up the gas generator. 

    And what’s with the special charging station comment? You plug this thing into a 115 VAC receptacle in your garage. Want to cut the charge time in half, wire in a 220VAC receptacle.  Which is an easy thing to do by the way. 

    • 0 avatar
      Quentin

      The engine and integration of the engine into your EV is an expensive insurance policy (I’d guess, out of the air, $8000 or so).  Once EVs start hitting the market, I’m sure your local AAA would be happy to take a couple bucks per month to help you out in the rare occasion you miscalculate.  It would be simple enough, and cheap enough, to add a little more battery power an set the “fuel gauge” to the conservative side.  Give it enough battery to go X+15 miles but let it read empty at X miles.  Or, simply allow more use of the entire battery with an override to the minimum battery charge levels for the rare occasion you need it.  It is going to take a LOT of fuel to save $8000, especially if you can do a years worth of driving at less than 40 miles/drive.  Assuming you did exactly 40 miles/day for a year, that is only 14600 miles/year. 

      That is the problem with the Volt, IMO.  The range is so short that it will likely use the gen mode quite often if you put substantial miles on your car.  If you don’t put high miles on your car, you’ll never drive enough miles to make up for the initial cost of entry over a comparable hybrid or petrol/diesel vehicle.  Catch 22.

  • avatar
    oldowl

    Aside from the propulsion questions, what kind of vehicle is/will be the Volt? A sedan? A faux sedan with semi-hatchback rear opening? Or just a  Malibu with a electric ticker?

  • avatar
    T2

    PeteMoran – you wrote earlier

    Engine power is power regardless of diesel or gasoline combustion. The generator would be matched accordingly.

    Assuming we are trying to avoid backyard engineering, then matching of the generator to a diesel characteristic is difficult with varying power. You are striving for both optimal efficiency and optimal efficacy. The generator wants to be supplied with constant torque to be able to provide the maximum current it can. The dipping torque characteristic between 2400rpm and 4200rpm puts a crimp in that. The diesel will reach its full nameplate power but the generator won’t be able to do the same since its current will need to be down by 33% to avoid stalling out the engine. This is poor efficacy compared to a gasoline engine which is able to utilise the same generator to its fullest extent.

    Thanks to BrockLlanders for supplying some other cogent reasons for eschewing diesels.

    • 0 avatar
      PeteMoran

      @ T2
       
      I don’t follow why you pick 2400rpm to 4200rpm. If you’re being specific about a known product combination then you ought to say so. It’s possible to design an efficient diesel-permanent magnet gen-set that operates at 500rpm if you wanted to.
       
      The key point being, that the generator characteristic matches the input engine power.

  • avatar
    educatordan

    This thread is starting to remind me of the one that asked the B&B about why some manufacture didn’t just develop a system like they use on trains with a diesel engine generating power for electric motors and batteries.  Deja Vu all over again.

  • avatar
    Carlson Fan

    “If you don’t put high miles on your car, you’ll never drive enough miles to make up for the initial cost of entry over a comparable hybrid or petrol/diesel vehicle.  Catch 22.”

    I doubt anyone driving a current hybrid does so because they otherwise couldn’t afford to put gas in a non-hybrid car.  So the popularity of the Prius really has nothing to do with econmomics. It’s about consuming less gas.  As EV cars become more popular, their cost will come down while the price of a gallon of gas continues to rise. Eventually cars like the Volt will make economic sense but not  initially. 

  • avatar
    Carlson Fan

    “Assuming you did exactly 40 miles/day for a year, that is only 14600 miles/year.” 

    First – that’s alot of miles in a year. A car we leased which was also used as a daily commuter  had under 20K after 3 years.
     
    Secondly – Your total yearly mileage figure calculation is flawed.  Anytime the car is sitting  at home it can be recharging. In my scenario I could easily get 60-70 miles a day out of the Volt without ever running the generator. I suspect my situation is not unique. 
     

    • 0 avatar
      Quentin

      I put 20k miles on my GTI/year due to lots of weekend leisure travel.  We put less than 10k/year on our MINI.  The fact that you drive so little makes the Volt make less sense.  The cost of entry is enormous versus the benefit due to the fact you only put 7000 miles/year on your car.  That translates into less than $900/year at $4/gal.  So, you’re willing to spend $33,000 (after subsidies) for a 4 seater compact that saves you $900/year in fuel?  As far as the “green cred”, you are already pulling your weight by driving minimal miles.  If you drive so few miles, why bother with a extended range EV?  Why not get 1 EV for short range driving and use a normal, 35mpg vehicle for the rare trips with mileage over the EV range?  My point is, by this car trying to be a jack of all trades, it adds additional cost and complexity without significant advantages.

      How is my mileage calculation flawed?  Your assumption is that you will be able to charge multiple times/day if you are getting over 40 miles of EV range.  Most of my weekday travel that includes more than just a commute is done immediately after work.  I don’t know of too many people that plan on getting home at 5:00, put the car back on the charger for 2 hrs, and then run out and do another 40 mile round trip drive.  If you are paying for all that extended range jazz, it seems insane not to use it, especially when multiple daily charging significantly inconveniences you as far as time goes.

    • 0 avatar
      Steven02

      @Quentin
      If you want to get to the calculations of how cost effective a Volt is, it won’t win.  Neither will a Prius.  Neither will a Fusion hybrid.  Neither will any hybrid that has been made.  A Prius starts at 7k higher than a Corolla.  Assuming $3 gas, 50mpg for the Prius and 30mpg for the Corolla, you would need to drive 175,000 miles before you make up the differences.  As gas rises, you would need to drive less, but that also assumes that you aren’t financing the extra 7k.  Hybrids do not make sense when it is concerned to cost.
      Also, weekday travel, you are correct, most of the time, people will run errands right after work if they do it at all.  Weekend travel, that is a different story and people will be able to recharge the battery.

    • 0 avatar
      PeteMoran

      @ Steven02
       
      Hybrids do not make sense when it is concerned to cost.
       
      A common refrain, maybe it feels like it if you pay cash. It depends on your city/highway driving. Rising fuel prices (a near guarantee) just makes the equation better and better.
       
      If you lease a hybrid you are ahead from day one. You also do better on resale. Our company operates a number of hybrid Camrys and they’re proving to have a lower TCO than regular Camry, including purchase.
       
      Our company is running/auditing a major trial of Hybrid trucks for a large Australian transport company; the Hybrids are light years ahead on TCO. Results should be published soon.
       
      Plus, and this seems not to concern many in the USofA I know, you save barrels and barrels of OIL.

    • 0 avatar
      Steven02

      @PeteMoran
      TCO can make a large difference, I agree there.  The type of driving you do can also make a large difference.  In your TCO calculations, are battery replacement costs included?  With a standard car, you will eventually need to rebuild a tranny.  In a hybrid, you will eventually have to replace the batteries.  I would highly recommend including that if you haven’t.  I would be surprised if the batteries in most hybrids made it past 10 years.

    • 0 avatar
      PeteMoran

      @ Steven02
       
      I would be surprised if the batteries in most hybrids made it past 10 years.
       
      Makes it a close call for Toyota offering standard no-questions-asked ten year warranty on batteries then.
       
      Toyota (again) say its not “age” as such it’s cycles and there is now a large knowledge base of very high mileage hybrids, taxis’ especially. Toyota seem confident that the battery pack will last the life of the car. I’m not aware of any examples of battery failures. Even then, looks like we’ll make enough of a saving over the lifetime of the car to still be way ahead should the battery eventually need to be changed.

  • avatar
    Carlson Fan

    “How is my mileage calculation flawed?”

    What about weekends, people that work from home, people that stay home with their kids, or those that are retired? I’m just saying not everyone parks their car in the company parking lot Monday thru Friday.

    “So, you’re willing to spend $33,000 (after subsidies) for a 4 seater compact that saves you $900/year in fuel?” 

    Yep! I agree with you that the econmomics aren’t there yet for the Volt so people will not be choosing it over a traditional car to save money. Plus let’s face it, even if it cost 26K-28K to get off the lot, that is still too expensive for a lot of people these days. For me the pay-off is driving past gas stations. But eventually the economics will swing the other way as the technology improves and manufacturing costs improve. 

    I don’t think this car will in and by itself save GM. But I do think it’s where the future is headed and I applaud GM for building it. I’m not aware of any EV cars that have the capability and refinement that the Volt promises.  Provide a link and I’ll take a look.

  • avatar
    Steven02

    Maybe I didn’t read the same article as Edward, but where do they say it isn’t going to get 50mpg in charge sustaining mode.

  • avatar
    Kyle Schellenberg

    I think Pfizer is working on a pill for Range Anxiety.

  • avatar
    T2

    don’t follow why you pick 2400rpm to 4200rpm. If you’re being specific about a known product combination then you ought to say so. It’s possible to design an efficient diesel-permanent magnet gen-set that operates at 500rpm if you wanted to.
     
    Ok , for what it’s worth – why you pick 2400rpm to 4200rpm - I have been baselining my argument on quoted figures for the 3 cyl turbodiesel from the SMART Fortwo as follows :

    Max torque 74lbs-ft @ 2400 rpm dropping to 50lbs-ft @ 4200 rpm.
    A 75% speed increase from 2400 rpm is accompanied by a 32% torque decrease.
    It so happens that I have also taken the Smart vehicle for a test drive on back streets and concur with the published figures. Torque sure drops off quickly when accelerating in any specific gear !!
     
    And yes I don’t deny It’s possible to design an efficient diesel-permanent magnet gen-set that operates at 500rpm if you wanted to. Sure if you specify a specific rpm you can select a generator to be at optimum efficiency at that particular fixed rpm when supplying maximum power. But that’s not the case here.
     
    The genset for the Volt will be required to run over a whole range of power demands when the battery approaches a state of charge of about 30%. You want the engine to be running at differing speeds but always at max torque as often as possible, similar to the operation of the Prius, in order to attain a high mechanical efficiency for your engine. However a 32% torque drop off above 2400 rpm is not going to sit well with the generator. It will need be sized for 74lbs-ft to take advantage of the torque heavy diesel characteristic at 2400 rpm regardless of the fact that it will receive a lower 50lbs-ft at the system’s 4200 rpm top speed. Such a generator will therefore be 50% heavier and more costly than the one that a gasoline engine would require with its simply constant 50lbs-ft at all speeds.
    Nothing stops you from using the cheaper 50lbs-ft generator for this diesel but then you would have to leave 24 lbs-ft on the table at the lower rpms and just make the diesel run about 50% faster than it would have done when used with the more appropriate 74lbs-ft generator. Obviously making the diesel engine run faster while restricting the torque is going to impact system efficiency. ‘Nuff said. A Diesel here is not a good idea.
    You might be wondering why I have made it my business to research this. Well the reason is that I am in fact building a genset drive powertrain. To do that a couple of months ago I formed a mastermind group. I sold the idea to a group of aquaintances skilled in areas that I’m not. The result is that today I took delivery of our genset. The prime mover is a brand new utility 15Hp single cylinder air cooled gasoline engine. It is coupled by means of a V-belt to a 5.5Kw Yaskawa servo which serves as a generator. The whole assembly is mounted on an off-the-shelf, heavy duty, two wheel dolly so that we can move it around before it becomes resident in our target vehicle, an awd Chrysler minivan. We are now examining the use of a throttle body actuator from a fuel injected engine to operate the throttle linkage of our carbureted engine.
     
    The other half of the dynamic duo which makes up a GSD system is the inverter/ induction motor combo which will be driving the rear wheels after we’ve removed and severely shortened the rear shaft from the transfer case. Mounting the motor will be someone else’s job too. My role at this end will be to spoof the inverter bus voltage and the incoming 3-phase to make it appear as if this vector drive was really connected to a genuine 460vac 60hz supply. In actuality its power rectifier section will be seeing anything but.
     
    The inverter control electronics will be getting a standard 115vac input courtesy of the 12vdc battery using an off-the-shelf 500watt 12vdc to 115vac converter. An earlier forensic examination was conducted to see how this 115vac input would be used internally. I discovered the designers had used a pair of off-the-shelf switchers – this time to step the 115vac back down for their low voltage circuits, LOL.

    The trick is to know what not to do. The likelihood of a successful design is increased when you can avoid blind alleys. That’s why I come on to TTAC. I have the same theme usually. This is what you shouldn’t do. And this is why you shouldn’t be doing it.
    Unfortunately the drawbacks of both the Honda and Toyota systems are rarely discussed. Although the VOLT has been selected to be under the spotlight here, there is the feeling that all these designs are merely interim solutions while companies experiment with electric automotive traction. In my case I just decided to go ahead and build my version of the logical conclusion of these designs. When the 15Hp concept is up and running it won’t be such a large stretch to switch to a liquid cooled, high rpm, fuel injected engine with direct shaft coupling to the generator. Right now I am using the correct technology which is simply the affordable technology that is available.


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