Q & A With Pam Fletcher: Executive Chief Engineer For Chevrolet Volt

GM

JUN 18 2015 BY ERIC LOVEDAY 58

The recent Huffington Post’s “Women In Business Q&A” features Pamela Fletcher, executive chief engineer for the Chevrolet Volt.

Here’s a snippet of the interview:

Q: What have the highlights and challenges been during your tenure at General Motors?

A: Unquestionably, the biggest highlight has been being a part of a team that has made history in the auto industry. When the first Chevrolet Volt arrived in the market in late 2010 we didn’t know what to expect. Would customers buy Volts? How would they use them? Were our predictions on how much they’d use battery versus gas engine accurate? The Volt has been the best-selling plug-in vehicle in America. We have displaced more than 34 million gallons of gasoline as a result of our current generation Volt owners traveling more than 650 million all-electric miles. That’s pretty remarkable. At Chevrolet, we have every intention of creating more monumental experiences, the next being the 2016 Volt that will have an increased EV range of more than 30 percent and the all-electric Bolt after that.

Please do read the full Q&A over at the Huffington Post.

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58 Comments on "Q & A With Pam Fletcher: Executive Chief Engineer For Chevrolet Volt"

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Brian
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Brian

The only question I have for Ms. Fletcher is when will Chevrolet expand the Voltec drivetrain into more/larger vehicles? I’m not talking about another ELR. I’m talking about a full-sized sedan, crossover, or small SUV.

Sean
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Sean

The Malibu is getting the Volt drivetrain soon. Lots of articles on that. I too would like to know if they are going to load it into trucks, SUVs, crossovers, vans. I would like a more useful vehicle (space wise) with the Volt drivetrain.

Spider-Dan
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Spider-Dan

It seems like the Malibu is not really getting Voltec in the sense most would interpret (electric-only, then gas). It’s getting something more like Voltec’s cousin, or maybe half-sister.

Brian
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Brian

The Malibu you are referring to is getting “Voltec-lite”. It’s a Voltec-based hybrid system which is missing the single most important feature – the plug. It is an impressive hybrid, but it is ultimately no better than a Prius. Therefore, I really don’t care about it.

Rick
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Rick

Will it reduce oil consumption? If so, then why don’t you care? Making “better” the enemy of “best” is counterproductive.

Djoni
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Djoni

O.K. then just say it’s best to have a plug!
Sheee..

Brian
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Brian

If it doesn’t have a plug, it is still 100% addicted to oil.

wavelet
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wavelet

Actually, it’s not at all evident it would reduce overall oil consumption. If you make it cheaper to drive, many people drive more…
Hybrids do better at very specific conditions.
W
hen hybrids started coming out for large SUVs, people bought them so they could greenwash themselves; never mind that a hybrid SUV eats a lot more gas than a bog-standard gas ICE compact, which is all they needed in the first place (and if you take into account the total environmental footprint of that SUV, it gets worse).

Speculawyer
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Speculawyer

+100

That is the question I would most want to ask as well.

bro1999
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bro1999

I asked her that very question at the DC Auto Show this past February. Of course, she gave the canned “We can’t comment on future vehicles” line, but she also said “I would be yanked off stage if I even attempted to answer that one”….which gives me the impression there is a larger Voltec vehicle in the pipeline. Whether she had the plug-in CT6, Malibu hybrid, or an actual Voltec CUV in mind, who knows. IMO, there is a Voltec CUV/SUV in the works.

bro1999
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bro1999

***question being “Are there any larger platform vehicles coming out soon with the Voltec powertrain?”

vdiv
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vdiv

A good question may have been what is taking GM so long and why is GM letting Mitsubishi, Porsche, and even BMW beat them in that market.

And oh, yeah, Tesla too.

ModernMarvelFan
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ModernMarvelFan

Don’t forget about Volvo…

I believe that is the first one to the US…

ModernMarvelFan
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ModernMarvelFan

That “rumor” has been around for a while now…

But I haven yet to see it coming true.

I can’t wait for a Voltec based Equinox.

Assaf
Guest

Awesome and good luck with the Gen 2 and the Bolt!

Seems that the way to move the Big Three into EVs for real, is to have more women at the helm. Go for it!

Lou Grinzo
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Lou Grinzo

The issue of more and bigger Voltec vehicles is fascinating, IMO, because it reveals a lot about how GM sees the market. Clearly they could have added at least one Voltec-ized SUV by now, for example, but chose not to because they thought they were better off not doing it. Why they would reach that conclusion is another issue. Given the number of people clamoring for such a vehicle, either there’s some sort of supply constraint or dealer issue, or GM has horribly misjudged the market.

bro1999
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bro1999

Perhaps GM is waiting until the costs of making a Voltec CUV come down to a certain point. Sales of the Equinox and Terrain are cash cows for GM, and they probably don’t want to take away from those sales with lower margin plug-in version sales. Just my 2 cents.

Josh
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GM has never been able to complete with the Rav4/CRV/Escape CUV class. They should have driven a stake into the heart of that class with a Voltec CUV.

It would not have eaten into their larger SUV sales, and wouldn’t have required much more total system power (for mountain mode) than the Volt.

A quiet, quick CUV getting 75 MPGe vs. 28 mpg would sway many drivers in that class. If they priced it within $3k of those competitors (after rebate), they would be looking at 6 figure sales numbers.

Josh
Guest

Hmm, looking at Equinox again, maybe it isn’t really bigger than the CRV and Rav4. It looks to me like Equinox has shrunk and the latter two have grown over the years.

I’ll have to retract that not competing in that class statement.

Lensman
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Lensman

Lou Grinzo said:

“Clearly they [GM] could have added at least one Voltec-ized SUV by now, for example, but chose not to because they thought they were better off not doing it. Why they would reach that conclusion is another issue.”

It’s pretty straightforward: No legacy auto maker, including GM, has any incentive to create EVs that will provide real competition with their own best-selling gas guzzlers. In fact, they have a rather strong disincentive to do so. That won’t change until PEVs are a significant portion of the market, and auto makers perceive there is real money to be made in that market sector.

In the meantime, expect real growth in the PEV market to come from auto makers with little or no legacy investment in making gas guzzlers; companies like Tesla and BYD.

wavelet
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wavelet

“It’s pretty straightforward: No legacy auto maker, including GM, has any incentive to create EVs that will provide real competition with their own best-selling gas guzzlers. In fact, they have a rather strong disincentive to do so. ”
Actually, that’s wrong. It’s a well known business maxim that it’s better to cannibalize yourself than to let a competitor do it… The Mitsubishi Outlander PHEV is eating everybody’s lunch outside the USA. it’s even offered in the tiny marlet here, although the price difference is high enough that there are almost no takers (and the ICE Outlander is the best selling SUV as it is).

The other reason you offer below (people aren’t willing to pay much more for a plug) is the real reason, as is the fact that all the vendors are battery-production constrained, so they can sell more vehicle $$$ using a given amount of production battery kWh with compacts than with SUVs.

Lensman
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Lensman
wavelet said: “It’s a well known business maxim that it’s better to cannibalize yourself than to let a competitor do it…” It may be “well known” but that doesn’t mean businesses pay any attention to it during a disruptive tech revolution. Eastman Kodak went bankrupt in 2012. Why? Altho the company actually developed the technology for digital cameras, it shelved the tech because the company recognized that selling digital cameras would cut into its core product of film cameras and film. It waited while rival companies developed and marketed their own digital cameras. When Kodak finally and reluctantly started making their own digital cameras, they were too far behind to compete… and went bankrupt. In 2013, Blackberry had lost so much of its once thriving business that it was seriously entertaining offers of a buyout. Why? Altho Blackberry started the smart phone revolution, it failed to keep up with the competition when Apple entered the field with its iPhone. You can easily find other historical examples, wavelet. The same thing happens in every disruptive tech revolution. Did you know Type-Writer was originally a brand name? Where is that company today? Long gone. Note the parallel between Blackberrry with its smart… Read more »
kdawg
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I wonder what kind of premium people would pay for a plug-in SUV/CUV?

For example, a base model Chevrolet Equinox is $22k. Let’s say GM wants to keep the same profit margins, and I’ll just throw out a SWAG that is $5K. So if they want to make $5k on a plug-in version, and the plug-in version cost $30K to produce, would people pay $35K for it? Assuming it has 40 miles of electric range then gets something like 38mpg after that.

What if the price was $40K?

I think car manufacturers will make plug-in versions of their SUVs if they can guarantee the same profits, or at least somewhere close.

ModernMarvelFan
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ModernMarvelFan

I would pay $40K for a 30 miles Voltec based Equinox.

I would even pay $43K for electric AWD version of the 30 miles Voltec based Equinox.

With federal incentives, it is basically the price of a loaded CR-V/RAV-4…

Speculawyer
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Speculawyer

That really would be a GREAT vehicle for the USA (and other) market.

GM are idiots for not having ready to bring to market.

As I’ve said many times, my conspiracy theory is that they probably were too afraid of having their conventional ICE SUV/CUV profits go away by bringing SUV/CUV PHEVs to market.

ModernMarvelFan
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ModernMarvelFan

“GM are idiots for not having ready to bring to market.”

I would agree with that. In fact, that is probably the #1 thing that existing Volt owner is asking GM for.

Although there are rumors that GM has been working on one, but I am just so surprised that it takes this long…

Now, with the new Equinox sharing the same platform as the Volt 2.0, there is even less excuse. Maybe GM can’t figure out how to offer a real 5-seater without taking away too much cargo room of the Equinox.

I would just break up the T-shape and still leave some in the center counsel and some underneath the 2nd row seat but move what in the leg room portion to where the spare tires are… That way, it should sacrifice too much cargo space. Even a small floor bump for battery cooling loops and cables are acceptable in my opinion…

kdawg
Guest

Remember back in 2011 when GM was testing a fleet of 5 (I think) pure electric Chevy Equinoxes. They had them up in Canada testing cold weather. Magna provided the powertrain at that time.

Lensman
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Lensman
kdawg asked: “I wonder what kind of premium people would pay for a plug-in SUV/CUV?” When surveyed, the average prospective car buyer says he’s not willing to pay much more for a PEV than an equivalent gas guzzler (see quote below). I think this is the #2 reason why legacy auto makers have not offered PEVs which are larger vehicles. (The #1 reason being, of course, that they don’t want to offer real competition to their best-selling gas guzzlers.) The larger the vehicle, the bigger the battery pack would have to be to give it even a halfway decent EV range (like the Volt or better), and thus the higher the markup would have to be as compared to the gas guzzler version. In other words: Auto makers perceive that if they did offer a significantly larger PEV, they would have to price it out of the market. Of course, EV enthusiasts will eagerly point to the RAV4 EV as a counter-example, but that compliance vehicle isn’t a real test case. As with all compliance cars, the sales price is not a true reflection of the cost of low-volume production; the vehicle is sold far below the car maker’s break-even… Read more »
Cleaner
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Perhaps its all about profit margins. The Volt was justified by getting non-GM shoppers into the showrooms and maybe buying the Cruze. SUV’s and trucks are the most popular vehicles and if they had a plug in SUV it would be less profitable and steal sales from their cash cows. Only when a competitor has the capacity to take SUV sales away from GM will they market a plug in SUV.

Brian
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Brian

At this point, if anyone is going to challenge them in will be either Ford (in the US) or VW (globally). Both offer decent PHEVs which, while they don’t offer the AER of the Volt, they still challenge it in terms of market share. The Volt could very well remain the best selling plug-in model, but it stands mostly alone (ELR sales are small). By comparison, Ford and VW each have multiple models which may sell less than the Volt, but put together could easily outsell it. Ford is coming awfully close to beating out GM these days, precisely because they put their Energi drivetrain into multiple models.

Lensman
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Lensman
But the Ford entries, unlike the Volt, don’t offer sufficient all-electric range to replace over half of an average driver’s daily gas-powered miles with electric-powered ones. They say “half a loaf is better than none”, but with the Ford Energi cars, it’s more like a quarter of a loaf. I hope I’m not coming across here as the sort of holier-than-thou EV “purist” who refuses to admit the Volt is a real PEV. The goal of EV enthusiasts should not be to promote all EVs as though they’re equal; the goal should be to actually replace as many oil-powered vehicle miles with electricity-powered miles. There are PEVs with sufficient range that they actually do that; PEVs such as the Leaf and the Volt and the Model S. And then there are the wimpy PEVs with an electric range of 20 miles or less; PEVs like the Ford Energi models, or the Mitsubishi Outlander, which don’t actually reduce overall gasoline consumption more than a relatively fuel-efficient gas guzzler like a VW Golf or a Honda Civic. Wimpy PEVs that might actually increase overall gas consumption, because slightly decreasing demand for gasoline significantly lowers the at-the-pump price, which in turn causes people… Read more »
tom911
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tom911

Compact CUV’s are the fastest growing market segment. I’m on my 2nd Volt and after 3+ year I’m still waiting for a larger platform. It seems to me they would sell a lot more if they offered a plug-in CUV like the Volt. Come on GM…!

Ziv
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Ziv

Same here. My Volt lease ends next June and I will be buying an electric car if I can find one under $40k that has more backseat room and at least 20 miles of AER. I wish it could have been a Gen II Volt, but I am not going to lease another car with a backseat that cramped.

Breezy
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Breezy

“While I can’t give away too much more when it comes to the vehicles we’re working on after [the 2016 Volt], I can tell you our team is committed to delivering exciting, affordable and game-changing electric vehicles like the Chevrolet Bolt in the next several years. You’ll have to stay tuned for more on that.”

Robert
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Robert

I would like to know why they can’t release updates for the Infotainment system? Or have a way to upgrade it to a new Mylink system.

Bill Howland
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Bill Howland

Agree with Brian that any important questions she either does not know the answer or ‘would be yanked off the stage if she answered’ this is just one of those perfunctory ‘womens’ articles where her sex is the emphasis – unlike Barra, I don’t think this lady knows anything, and her value is just window dressing, or possibly a comedic element, such as when she started talking on those volt deep dives about ‘reactionary forces’ and then you see the camera pan, and all the actual engineers cringe.

kdawg
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Give her some credit (she’s a fellow GMI alum) 🙂

Here is some good background info on PF.

http://shebuyscars.com/drives-pam-fletcher-chief-engineer-behind-new-chevy-volt/

Bill Howland
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Bill Howland
I have nothing against Ms. Fletcher, although I feel it is at least ok to mention statements coming out of her own mouth. We had a somewhat similiar situation at work. We had a business type blonde who seemed to be sleeping with most of the people promoting her, to a boss’s boss’s boss, these technical people saying she’s ‘smart as a whip’, works well with people, etc. But she’d be an embarrassement at schools because in the case I’m talking about, this ‘fantastic electrical genius’ couldn’t figure out how to arrange 2 penlight (AA) batteries to give 3 volts, or would wire a switch directly across a light bulb so that you could turn a light off but never turn it on again. That kind of thing. Obviously the great reviews were due to social skills and abilities outside of work. I never complained, but then I worked for the company. I don’t work for GM (I only spend money on their end results), so while I couldn’t critique an incompetant (or, ahem, incompetant at the $200K job she was ostensibly paid for), – thats why such ladies are known as the ‘head engineers’.
Lensman
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Lensman
Rick said: “Will it reduce oil consumption? If so, then why don’t you care? Making ‘better’ the enemy of ‘best’ is counterproductive.” The problem with this argument is the assumption that increasing efficiency in gas/diesel guzzlers actually reduces overall petroleum consumption. Does it, really? Or does it actually promote even more consumption, because higher efficiency means it’s cheaper per mile to run it, so people use it more? To quote from the “Jevons paradox” article at Wikipedia: “In 1865, the English economist William Stanley Jevons observed that technological improvements that increased the efficiency of coal-use led to the increased consumption of coal in a wide range of industries. He argued that, contrary to common intuition, technological progress could not be relied upon to reduce fuel consumption.” source: https://en.wikipedia.org/wiki/Jevons_paradox With rising numbers of gas guzzlers being sold in India, China, and other countries with rising levels of industry, if one person saves a bit on gasoline by driving a more fuel-efficient car, at best that will just reserve a bit more oil to be burned tomorrow by someone else. The only way to actually reduce overall consumption of fossil fuels in powering transportation is to replace fossil-fuel-powered vehicle miles with electric-powered… Read more »
Djoni
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Djoni

This is something that I learn right here on insideev.
Very telling.
Thank you Lens,

ModernMarvelFan
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ModernMarvelFan

Pam should produce another “educational” video on youtube like the Gen 1 Voltec deep dive to explain to the “average joe” that how much simpler a Voltec is compared with a 8-speed transmission so those Youtube channel learning fans would get a clue…

Lensman
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Lensman

ModernMarvelFan, you have a very strange idea about what constitutes complexity in the operation of a drivetrain… and what doesn’t. A typical ICE drivetrain, whether it has 8 gears or 80, has only one set of gears engaged at any time. Merely increasing the number of moving parts doesn’t necessarily mean the actual operation of the drivetrain is any more complex.

I see that you’ve somehow convinced yourself that Voltec is approximately as complex as a rubber band powered toy car. 🙂 But for others reading this post, for those who are interested in actually learning something about how Voltec works, here’s an article about the new Voltec 2.0. An article which explains, for example, why it has three clutches and five different drive modes:

http://gmauthority.com/blog/2015/02/secrets-of-the-2016-chevrolet-volt-transmission-deep-dive/

Now, ModernMarvelFan, that ICE drivetrain with 8 gears you keep mentioning? How many clutches does it have? I’m guessing just one.

ModernMarvelFan
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ModernMarvelFan
Lensman, “you have a very strange idea about what constitutes complexity in the operation of a drivetrain… and what doesn’t” NO, I don’t. I use the standard definition of “mechanical complexity” which involves the numbers of moving parts and acutators, pumpings, clutches, solenoids…etc. “A typical ICE drivetrain, whether it has 8 gears or 80, has only one set of gears engaged at any time. Merely increasing the number of moving parts doesn’t necessarily mean the actual operation of the drivetrain is any more complex.” LOL. So, how many set of gears does Voltec engaged at any time? The same set everytime for every mode that Voltec is operating. For a given planetary gearset, the relative motions of Ring, planet and sun gears are always in relative motion to transmit power. In the case of Voltec, it is really a power split input device which means that a single output with 2 sources of power input which can be disabled/enabled by 1 clutch. The so called additional clutches are part of the external power input chain which engages ICE to generator and generator to the ring wheel. But I will even count them for your sake. “I see that you’ve somehow… Read more »
Djoni
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Djoni

This is a mastercourse in mechanical basic.
Make my day.
Still, how do a simple final reduction gearing sounds between those two.
Like you mentioned, much, much simplier.
This is because there no ICE involved, there’s no need for it, and although some kinky engineer think it could help to put one in line, Tesla, Leaf, I3, SmartED, FitEV, Fiat500e and lot of others to come don’t and won’t.

ModernMarvelFan
Guest
ModernMarvelFan
Well, it is a good question you raised. The engineering here is about trade off. A 1-speed reduction would be simpler. But if you look at the Voltec, it is effective a very capable 1-speed as well. When that ring gear is locked, it is effectively a single speed reduction gear. Just as simple as any compact 1 speed transmission out there (many 1 speed gear box are also just a planetary gearset like the Voltec). The only added complexity here is the control of the ring gear which wouldn’t be needed in otherwise a 1-speed design. But that added complexity on the ring gear is to add functionality that other single speed gear box BEV doesn’t have. The single BEV gearbox all have the issues of trade off between low speed performance and top speed efficiency. So, most of them have significant power drop off past 40mph. Tesla compensate for that by having a much higher drive voltage which requires a much larger battery (cost more but brings other benefit). All other single speed BEV basically sacrifice high speed efficiency and power by gearing it low so the car would have great low end performance. Voltec allows a second… Read more »
Lensman
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Lensman

ModernMarvelFan said:

“After reading and learning from a quick crash course on how complext transmissions are, you would at least admit that Voltec is actually relative simple in its design.”

No informed and sensible person would make such a claim. The operation of a transmission is so simple and straightforward that anyone with a reasonable amount of mechanical aptitude can figure out how it works just by looking at it.

Contrariwise, to understand Voltec, we need to watch a video which runs for several minutes, to have even a theoretical understanding of why it has five different operational modes!

Merely adding more gear ratios doesn’t make an ordinary transmission operationally any more complex or difficult to understand, and claiming otherwise is downright silly. Compared to the five different operational modes of Voltec, it’s downright simple and straightforward.

ModernMarvelFan, refusing to admit you’ve been shown to be wrong is merely compounding your error. Doubling down on your mistake with wall-of-text comments isn’t going to help you convince anyone; rather the opposite.

ModernMarvelFan
Guest
ModernMarvelFan
“Contrariwise, to understand Voltec, we need to watch a video which runs for several minutes, to have even a theoretical understanding of why it has five different operational modes!” You used the word “we” here. Please leave that to yourself. As far as so called modes go, you are easily confused with mechanical complexity and software complexity. I am pretty sure you would need a longer video to explain how Tesla electronically controlled its different operation models with its motor drives system in details. Most of people that includes you wouldn’t even understand it even if a 3 phase motor controller is explained in detail… Using a video in Voltec control as your base to claim for complexity only shows how little you know about transmission or cars in general… “Merely adding more gear ratios doesn’t make an ordinary transmission operationally any more complex or difficult to understand, and claiming otherwise is downright silly. Compared to the five different operational modes of Voltec, it’s downright simple and straightforward.” LOL. That is stupidist logic I heard. How about this, please find me a video or let me put it this way, please explain how each of the clutches and actuators and… Read more »
ModernMarvelFan
Guest
ModernMarvelFan

Lensman wrote:

“Merely adding more gear ratios doesn’t make an ordinary transmission operationally any more complex or difficult to understand, and claiming otherwise is downright silly. Compared to the five different operational modes of Voltec, it’s downright simple and straightforward.”

I have to key on this one. Because it is so funny…

Hey dude, learn to count. The Voltec has 3 clutches, 1 planetary gearset with 5 mode.

An 8-speed automatic transmission such as the one by ZF has 5 clutches, 4 planetary gearset with at least 8 modes (1 for each speed gear)…

I guess you are also bad in math… LOL.

Priusmaniac
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Priusmaniac

I would definitly ask the answer to what is killing the car widespread success possibilities, why did you keep the b part of the battery knowing that it would prevent a normal backseat with room for the middle man feet?

Who would think about placing a battery where the front passenger seat is, so why do that with the central backseat passenger.

It spoils the entire car for the 20% of families with 3 children and also for the ones that want a car with a full 5 seats for other reasons.

Bandman29
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Bandman29

I wonder if anyone important, with any kind of decision making power, is reading any of this. If so, then I strongly suggest that a small CUV with the Voltec power train (including the plug), would satisfy most of the concerns expressed here.

Bill Howland
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Bill Howland

I’ve never worried about that electric motor/gearbox setup in the volt since it is basically the same as that ‘synergy drive’ used in toyotas, in that case made by a toyota subsidiary, – supposedly GM makes theirs themselves now, whether under license from this japanese firm or not.

I also know GM has had good luck with similiar planetary gear trains in cadillac escallade hybrids – so I’d assume most of the ‘bugs’ are out of them.

Apparently Chrysler doesn’t think many-speed ICE automatics are a trivial problem, since their flagship jeep was held up and later recalled due to these new transmissions.

ModernMarvelFan
Guest
ModernMarvelFan

Yes, both Voltec and Synergy are quite clever and simple in their design. Synergy is slightly simpler due to the main traction motor is always connected to the ring gear and wheel directly so it doesn’t have clutch or the mode to allow it to operate in 2-electrical motor mode since it is NOT designed to operate at high speed electrically only.

Comparing to a high gears automatics, it is just far simpler and more elegant. Companies has been working on 8/9/10 speed automatics for years and they are expensive large and complex.

Just comparing the simple size, people would have known why those automatics would need rebuilding after about 150K-200K miles (sometimes as early as 80K to 100K miles).

Of course, the familiarities with automatics tend to make people think that they are simple where the unfamilarities with Voltec or Synergy would make people think they are complex…

Djoni
Guest
Djoni

Just agreed with everything you write MMF.

Multiple speed transmission are very sophisticated piece of engineering and manufacturing. Let alone trying to understant or repair it.
I wish some over here just try to open and successfully reclose one, just to consider the task.

On the other hand, three phase motor that are label as ingeniously simple ain’t so simple to someone who don’t enven understand rotating field.
For some, it might be obscur science.
By extension, the software controlling the inverter for such a motor might be totally mind bogling for most, not including the power elctronic it require,but it is of much higher reliability and expected longer life than almost anything mechanical.
And as battery will get more capacity, getting more amps and voltage from it would greatly reduce the limitation of discrepency in low vs high speed situation with very high torque low rev electric motor that would be as efficient as anything but without a multiple ratio complexity added.
However, it might be economical to go other ways for the time being.

ModernMarvelFan
Guest
ModernMarvelFan

Agreed completely!

Finally someone who has the technical understanding…

One thing to note that is even if we are getting better motors and controllers, the magnetic saturation or EMF generated by the high spinning speed of the motor will always be an issue for high speed requirement. The good thing is that most cars don’t require 200mph speed. =)

Bill Howland
Guest
Bill Howland

The problem with lowered efficiency and low power factor at high speeds is mostly incurred by Tesla products since they only to date use induction motors, probably because they feel they have to use the development Nikoli is usually credited. (I don’t think most people worry about this so I would think it would not be heresy if a non-tesla-motor ever showed up in one of their products). GM stuff is less affected by this owing to:

1). Permanent magnet motors (synchronous)
2). Slower motor speeds on average.

ModernMarvelFan
Guest
ModernMarvelFan

Even with PM motors, you still run into saturation issues if the rpm gets high enough.

GM’s motor rpm is lower due to the gearing ratio. That just mean that you are giving up some of the 0-60mph performance in trade off to higher speed with fixed ratio gearbox. With Voltec, you get to modulate the ratio in order to gain some efficiency…

Bill Howland
Guest
Bill Howland

OH boy, you’ll have to explain that one to me MMF. With increasing speed, saturation becomes LESS of a problem since the frequency is increasing yet the battery voltage cant be more than 400 volts.

THe loss problem in the stator is due to Hysteresis losses becoming proportional to the frequency, whereas the volts/frequency ratio is constantly decreasing and so increasingly distancing itself from saturation.

There’s a lot of crap on the internet by people who have never been around an AC motor.

There are no rotor current losses in a synchronous motor simply for the reason that there are no rotor currents to begin with.

I think that like the lightning arrester issue, you are using too much conjecture here.

Djoni
Guest
Djoni

O.K. I’m late with that one, but here is my thought.
Altought I don’t have mastered in electric motors and no pretending knowing it all, I have to say that your comment is a bit confusing.
It might be other factor than saturation, I didn’t check it, but all electric motors have limit and efficiency issue with higher r.p.m ans it doesn’t matter which type it is.
It might be CEMF, it might be physical centrifugal force, it might be electrical resistance loss or other’s, but the thing is they all have limit.