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I signed up for the panel a year or 2 ago, and I've been getting surveys here and there since then. Most of the surveys are rather bland (what do you think about the name of this described feature?) stuff like that, but the one I got yesterday was very interesting.

It was titled "EV Power Train Tradeoffs". I believe that only Bolt EV owners received this survey, as the Bolt was specifically mentioned in a lot of the questions.

The first half of the survey tossed me questions such as how important I considered towing capability for an EV, questions about what maximum % range loss I would find acceptable during winter months, what % of battery degradation I found acceptable over a 3 year period, what minimum range a vehicle needed for me to consider buying a new EV today (150/200/250/300/400). I think there was also a question about whether I would buy a luxury version of a Bolt.

2nd half of the survey gave me a couple dozen questions that included specifications fictional BEVs, to include range (150-400 miles), 0-60 time (4-10 seconds), battery degradation over 36 months (5-15%), fast charging speed (90 miles/30 min - 200 miles/15 minutes , annual operating costs ($500-1500), 1 pedal or 2 pedal driving, and the price compared to an equivalent gas car.

Here is one of the fictional cars I was presented (I'll take this one today!):

upload image

I gave range, fast charging, and battery longevity priority when responding to the questions.

Seems GM's plan for 20 new EVs in the next 5 years statement was not just a dog and pony show and they are serious about it, unlike some other companies in...oh, Silicon Valley that promise the world and deliver nothing but disappointment.
 

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Bingo - it is exactly what is says. They are balancing tradeoffs and looking for data on what to balance for. This kind of balancing takes a long time and lot of intuition, in my experience the customer data you are providing usually tells you more or less what you already know, so ends up be a type of validation. A problem though is that people often act differently than what they say. It's hard to get an accurate read on what they want when they go to actually buy a product, despite what they said in a survey.

Seems GM's plan for 20 new EVs in the next 5 years statement was not just a dog and pony show and they are serious about it, unlike some other companies in...oh, Silicon Valley that promise the world and deliver nothing but disappointment.
You know of all companies GM is the stealth innovator here. They got a 25 year pass to do R&D on BEV's since the EV1, without the burden of having to release product. You can troll the conference papers to see all the work they did in that period. In 2010 for example they published the results of their research into BEV motors, and found that power wound results in a 20ºC cooler motor compared to magnet wire (note Tesla opted for magnet wire, and had to then go with a water jacket to cool it, all of which is highly inefficient in addition to their pure induction motors). Anyhow with the Bolt we get the advantage of that 25 year research.
 

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In comparing the Bolt motor to the Tesla motor, I assume by "power wound" you mean the permanent magnet structure on the rotor of the Bolt motor vs the wire wound armature of the Tesla motor. It is important to keep permanent magnets (Samarium Cobalt or Neodynium Iron Boron) cool because the demagnetize at elevated temperatures. Hoping mine stay cool.:nerd:

Bingo - it is exactly what is says. They are balancing tradeoffs and looking for data on what to balance for. This kind of balancing takes a long time and lot of intuition, in my experience the customer data you are providing usually tells you more or less what you already know, so ends up be a type of validation. A problem though is that people often act differently than what they say. It's hard to get an accurate read on what they want when they go to actually buy a product, despite what they said in a survey.



You know of all companies GM is the stealth innovator here. They got a 25 year pass to do R&D on BEV's since the EV1, without the burden of having to release product. You can troll the conference papers to see all the work they did in that period. In 2010 for example they published the results of their research into BEV motors, and found that power wound results in a 20ºC cooler motor compared to magnet wire (note Tesla opted for magnet wire, and had to then go with a water jacket to cool it, all of which is highly inefficient in addition to their pure induction motors). Anyhow with the Bolt we get the advantage of that 25 year research.
 

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In comparing the Bolt motor to the Tesla motor, I assume by "power wound" you mean the permanent magnet structure on the rotor of the Bolt motor vs the wire wound armature of the Tesla motor. It is important to keep permanent magnets (Samarium Cobalt or Neodynium Iron Boron) cool because the demagnetize at elevated temperatures. Hoping mine stay cool.
Two things, one is that Tesla went with Nikola Teslas pure induction motor which uses no permanent magnets. They have some posts about how superior it is, except it isn't, it's about 20% less efficient because you have to use power to generate the opposing magnetic field you get for free in a AC perm magnet motor like the Bolt. So you generate heat this way and each mile costs more kWh than a perm magnet.

The second is that they use ordinary magnet wire - thin strand lacquered wire. The Bolt uses rectangular bars, which have higher current carrying capacity among other beneficial features. The downside is it's more expensive to manufacture. If you go on YouTube the Tesla motors are just using the 100 year old magnet wire spool method, cheap, easy and fast to get going. GM's approach is a far superior engineering solution but is harder to do. I don't even know, but it obviously takes some specialized equipment to make those precise bends. Regardless GM doesn't care, they are used to billion dollar manufacturing lines, and they outsourced the build to LG Korea anyhow. So the motor runs cooler, is far more efficient and more reliable. All for the cost of some rare-earth magnets and specially bent bar wiring. With this they can then use a superior cooling solution where the lubricating gearing & motor oil is passed over a heat exchanger to the glycol, so the water is kept nice and far away from the motor.

Technical details, but the consumer impact is a more robust motor that importantly uses far less power compared to a Tesla. This is one main contributor to why Tesla range results are poor, relative to the kWh they stuff in those cars. The other is the large size of their cars, but this highlights that their superior aero performance is probably not saving them here. The Bolt with it's merely good aero has the longest range of any BEV Consumer Reports has tested.
 

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The Bolt with it's merely good aero has the longest range of any BEV Consumer Reports has tested.
You've mentioned this a few times and you should probably be aware that the test you are referring to was run under somewhat sketchy conditions.
"
We make sure the car is in its version of normal drive mode, not extended range mode, because our goal is not to see what’s the maximum range an EV can get when pushed to its limits, but rather to see the total number of miles a driver should expect under normal circumstances.
We put our EVs into their less-aggressive regenerative braking mode; regenerative brakes help EVs recapture some of the energy lost in braking. Many EVs have a mode with aggressive regenerative braking that’s meant to capture more of that energy, but it can be an intrusive experience, making the brakes seem grabby, especially for drivers who are new to EVs."
https://insideevs.com/tesla-challenges-bolt-vs-model-s-range-eval-consumer-reports-elaborates/


Charging the tesla to 80 % and minimizing regen gives the Tesla a significant disadvantage. Any normal driver trying to maximize their range would have charged to 100% and set regen to high.
 

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You've mentioned this a few times and you should probably be aware that the test you are referring to was run under somewhat sketchy conditions.
I don't know about sketchy conditions, but naturally you're correct that range is very much driving dependent. To do it right you'd have to do an expensive test nobody will do, which is drive both cars under say 100 different driving tests and compare. Regardless, my point being is that the Bolt has a more efficient battery and drive train, and anecdotally I hear more from people getting lots of range from the Bolt more than it seems from Tesla owners, but take it for what it's worth.

But I'll be an equal opportunity offender and note the other induction motor design is the 2018 Leaf, I hear from an engineering colleague. Why oh why does anybody use a pure inductive motor in a BEV? Madness ... and I may have neglected to say above that Tesla silently went perm magnet on the 3, as has nearly every other company.
 

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Thanks, I understand the round wire versus bar argument. It is simply packing factor, in that with bars you can get more copper per cross section, which lowers resistance. So the magnets come for LG in Korea and probably the neodymium rare earth metal is extracted in China. The battery is also assembled by LG, I think. So GM did the design and attached the steering wheel! Ah, the global economy.


Two things, one is that Tesla went with Nikola Teslas pure induction motor which uses no permanent magnets. They have some posts about how superior it is, except it isn't, it's about 20% less efficient because you have to use power to generate the opposing magnetic field you get for free in a AC perm magnet motor like the Bolt. So you generate heat this way and each mile costs more kWh than a perm magnet.

The second is that they use ordinary magnet wire - thin strand lacquered wire. The Bolt uses rectangular bars, which have higher current carrying capacity among other beneficial features. The downside is it's more expensive to manufacture. If you go on YouTube the Tesla motors are just using the 100 year old magnet wire spool method, cheap, easy and fast to get going. GM's approach is a far superior engineering solution but is harder to do. I don't even know, but it obviously takes some specialized equipment to make those precise bends. Regardless GM doesn't care, they are used to billion dollar manufacturing lines, and they outsourced the build to LG Korea anyhow. So the motor runs cooler, is far more efficient and more reliable. All for the cost of some rare-earth magnets and specially bent bar wiring. With this they can then use a superior cooling solution where the lubricating gearing & motor oil is passed over a heat exchanger to the glycol, so the water is kept nice and far away from the motor.

Technical details, but the consumer impact is a more robust motor that importantly uses far less power compared to a Tesla. This is one main contributor to why Tesla range results are poor, relative to the kWh they stuff in those cars. The other is the large size of their cars, but this highlights that their superior aero performance is probably not saving them here. The Bolt with it's merely good aero has the longest range of any BEV Consumer Reports has tested.
 

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So lucky, bro1999. I postponed filling out the survey and my link was expired and I was no longer part of the panel. I loved answering the questions when I first got my Volt. Was really looking forward to answering w/r to the Bolt. Maybe shape the future and contribute to emergence of the CUV or SUV Voltec.
 

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So GM did the design and attached the steering wheel! Ah, the global economy.
Well that's considerably oversimplified, but you need to understand that the design is the most important part. Car manufacturers are a dime a dozen - the competitive advantage is the ability to design a product that performs according to the stated specs for minimum cost.

And the biggest part of the cost equation includes the understanding what the manufacturing cost is going to be. That's a very specialized set of knowledge and skills that can't be replicated by a cheap factory in China.
 

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I did this same survey. It seems they are evaluating options regarding motor design as well as battery design. Trying to figure out if people want long range, battery life, fast recharge, fast acceleration, one pedal driving with strong regen, or low cost. The fact that they kept asking about one pedal driving vs. two pedal driving tells me they are thinking of cheaper motors like Tesla has. To me anyhow, one pedal driving is very important. I love it.

Their survey is kind of like where I was going with my failed future battery poll thread. Engineering is always a trade off and just responding, "All of the above" is just not an option. You have to choose between this and that. Apparently, GM and I are close to the same page.
 

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Thanks, I understand the round wire versus bar argument. It is simply packing factor, in that with bars you can get more copper per cross section, which lowers resistance.
And high slot fill, short end-tun length, improved thermals and efficiency. The perm magnet V design results in better torque ripple without having to implement rotor skew, which again adds complexity. Here also is a GM study

For this drive cycle, GM found, a mild hybrid motor would have an average power requirement of about 3.4 kW. A full hybrid motor—such as Motor B in GM’s two-mode hybrid—would have an average power requirement of 5.2 kW. However, an extended range electric vehicle or a battery electric vehicle motor would have an average power requirement of 24.9 kW—more than four times that of the full hybrid system.

GM set up a thermal analysis to compare bar wound stator technology with conventional wire wound stators for this cycle. Bar winding uses rectangular wires instead of conventional round wire. The technology produces a higher copper fill (85-90% compared to 70%, according to GM).

Bar winding lowers winding resistance 30% or more, lowering overall losses when compared to conventional wire wound types. Bar wound motors also have 50% or more greater heat dissipation area when compared to stranded wound types. ...

While bar wound motors are somewhat cooler than wire wound for full hybrid applications, they run significantly cooler for Full EV driving, GM found. In a full hybrid application, the temperature delta was around 5 °C; in the EV application, the temperature delta was more than 20 ° C. A 20°C difference could double the life of the motor, Savagian noted, citing data from motor insulation providers.
 

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Their survey is kind of like where I was going with my failed future battery poll thread. Engineering is always a trade off and just responding, "All of the above" is just not an option. You have to choose between this and that. Apparently, GM and I are close to the same page.
It's tough making these surveys, too easy to confuse people or for it to be too complicated.

Something I'm wondering is if we'll see a lot of cost cutting. With the Bolt they apparently had a wide leash because they wanted to make a statement. Early communication was "< 200 mile range" which changed to "oops, no we meant > 200 mile range", and I think they're surprised to find it going upwards of 300 miles depending on driving. So from here I think we can expect more and more cost cutting - like we've seen with the back pocket and the auto heated steering wheel. Reason being sales were tepid until they came down by $4k-$5k, so somehow they need to hit that (battery should get cheaper by some 7%/year which will help).

I did this same survey. It seems they are evaluating options regarding motor design as well as battery design. Trying to figure out if people want long range, battery life, fast recharge, fast acceleration, one pedal driving with strong regen, or low cost. The fact that they kept asking about one pedal driving vs. two pedal driving tells me they are thinking of cheaper motors like Tesla has. To me anyhow, one pedal driving is very important. I love it.
I'm not sure what one pedal has to do with the motor? With either design you can have regenerative braking. One pedal is just a design/engineering choice, and GM favors it's own approach from what I can see.
 

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I'm not sure what one pedal has to do with the motor? With either design you can have regenerative braking. One pedal is just a design/engineering choice, and GM favors it's own approach from what I can see.
There's a big, big difference between engineering and marketing. They may be trying to evaluate which trim level or model line warrants some of these features. To the marketing department each additional feature can justify a higher price, even if it's free to implement. See: software unlocking of Tesla battery pack capacity.
 

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Well that's considerably oversimplified, but you need to understand that the design is the most important part. Car manufacturers are a dime a dozen - the competitive advantage is the ability to design a product that performs according to the stated specs for minimum cost.

And the biggest part of the cost equation includes the understanding what the manufacturing cost is going to be. That's a very specialized set of knowledge and skills that can't be replicated by a cheap factory in China.
I agree, but not confident that the Chinese won't be making great BEV's soon. They have a huge potential market. Also, what I see on the science side, is their government is investing much more in basic research than the US and we can't assume the status quo on knowledge and skills will prevail. I agree GM did a great job on the Bolt. Apple is basically a design house, with almost all manufacturing overseas. Hopefully, that isn't the path for the US car industry.
 

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There's a big, big difference between engineering and marketing. They may be trying to evaluate which trim level or model line warrants some of these features. To the marketing department each additional feature can justify a higher price, even if it's free to implement. See: software unlocking of Tesla battery pack capacity.
Oh I know, we all do it. Usually cheaper to manufacture one version and unlock features with software. I just didn't get what that has to do with the motor.

With all their market goodwill and established design Tesla can strip a car to its bare minimum and still book preorders (Model 3). What they've done is hook into the Apple design pattern. Make it simple and clean, strip out every piece of hardware you can and give people software features. I've harped on this before, the Tesla car model is really simple - simple motor, battery and such, the only thing they load up on is cameras and software. They even save on buttons, all it has is two on the steering, two steering column stubs, and a button or two like hazard lights. I'm not sure but I think to lower the windows you need to use the touch screen - crazy to my mind, but it's obviously working.

Anyhow long story short I think GM will continue to offer lots of little physical features like one pedal as a way to distinguish themselves, and also it's their established pattern that people expect.
 

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I'm not sure what one pedal has to do with the motor? With either design you can have regenerative braking. One pedal is just a design/engineering choice, and GM favors it's own approach from what I can see.
It was my understanding that true one pedal driving where the car can come to a complete stop and be held at a stop with nothing but regen requires a particular type of motor with permanent magnets and cars that don't have this motor, like Teslas, can't do it. However, I have since tried to do some Google research on the subject and it is very limited on what I could find. It does appear that the permanent magnet motor does afford stronger regen, but what actually brings the car to a complete stop is good ol' hydraulic friction brakes. I guess GM has cleverly created the software to seamlessly blend the power of regen with application of the friction brakes to stop the car.

Nissan has now taken this concept even further and the new Leaf applies the friction brakes strong enough to hold the car on a hill in all situations. As we know the Bolt can't do this, but it seems like a simple software tweak to be able to counter Nissan.
 

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It was my understanding that true one pedal driving where the car can come to a complete stop and be held at a stop with nothing but regen requires a particular type of motor with permanent magnets and cars that don't have this motor, like Teslas, can't do it. However, I have since tried to do some Google research on the subject and it is very limited on what I could find. It does appear that the permanent magnet motor does afford stronger regen, but what actually brings the car to a complete stop is good ol' hydraulic friction brakes. I guess GM has cleverly created the software to seamlessly blend the power of regen with application of the friction brakes to stop the car.
Ah OK you're talking about coming to a complete stop. First both perm and induction motors both can do regen, as you say perhaps perm can do better (or perhaps its just that you start losing efficiency since the gain from regen is lost to the inductive feed back into the motor, which is a general problem with pure induction anyhow). But on coming to a complete stop the Bolt manual and I've verified that the power to come to a stop is limited to being on a flat, if you want to end on a slope it won't stop you. My understanding is the Tesla & Leaf have the same capability of coming to a stop by regen (also only on a flat too I assume).

On using the brakes, the Bolt uses the Bosch iBooster system which has Bosch firmware that GM loads a profile into (I don't know if the profile is simply a table of points to generate a braking curve or of it includes microcode - I assume the former.) Physically the iBooster works by initially being regen and at some point in your braking it switches to hydraulic. The uploaded profile determines the ramp from one to another. In the Bolt's case my understanding is that it offers light regen at the beginning of the stroke and quickly moves to hydraulic, perhaps before the halfway point of the stroke.

Which I think is a reasonable choice, we have L one pedal, paddle and D regen, they probably figure if you are using the brakes you want to use the brakes.
 

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Its not so long ago that General Motors owned Electro-Motive Diesel (EMD) an American manufacturer of diesel-electric locomotives for railroads. The technology of traction motors for railroad locomotives must be very similar to that in the electric cars of today. Such traction motors have a long history going back at least to the early 1900s, with lots of measurements of different types of windings and armatures conducted by many companies both in the US and abroad. So, that GM has been able to come up with a decent motor for the Chevy Bolt EV is not a surprise. I doubt they started totally from scratch, but from quite a large knowledge base. GM sold EMD in 2005. Rectangular magnet wire is an idea that is pretty old. I was building electromagnets that way decades ago, though not for motors, and its certainly been used in railroad traction motors for a good fraction of the 20th century.
 
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