Chevrolet Spark EV

[RegGuheert]

I was pointed to http://www.teslamotors.com/blog/induction-versus-dc-brushless-motors" onclick="window.open(this.href);return false; long ago.

Thanks! So I guess the bottom line is that if you are building a very high-performance EV, you need to use an induction machine since the car will usually operate at a power level far below the peak and efficiency would suffer too much for normal driving with a synchronous machine. But peak efficiency is a couple percent lower with the induction machine.

So then I start to wonder if Tesla will move to a synchronous machine when they try to build an affordable EV for mass consumption.

 

[qwk]

I was pointed to http://www.teslamotors.com/blog/induction-versus-dc-brushless-motors" onclick="window.open(this.href);return false; long ago.

Thanks! So I guess the bottom line is that if you are building a very high-performance EV, you need to use an induction machine since the car will usually operate at a power level far below the peak and efficiency would suffer too much for normal driving with a synchronous machine. But peak efficiency is a couple percent lower with the induction machine.

So then I start to wonder if Tesla will move to a synchronous machine when they try to build an affordable EV for mass consumption.

I'm pretty sure that Tesla isn't going to go backward in motor technology. As far as an "affordable" car for the masses is concerned, $40k before incentives is probably going to be the lowest price that any new Tesla sells for. The term " affordable" is used, but that is a very broad and relative term.

 

[RegGuheert]

I'm pretty sure that Tesla isn't going to go backward in motor technology.

Backward? Synchronous machines should allow for a more efficient drivetrain than can be achieved using an induction machine.

 

[EricBayArea]

The Spark is meant to compete with the size of the Fiat and similar sized cars. The LEAF/Versa is a different size car. When I was in the market I was not interested in anything smaller than the LEAF for the simple fact that I have a dog a baby and the things that go along with both. This car is too small for me.

 

[Smidge204]

A synchronous motor would need brushes and wound rotors or permanent magnet rotors.

Permanent magnets have lots of problems - they are difficult and dangerous to handle during assembly, and contain "rare earth" minerals which include cost and supply woes. Wound rotors would need active cooling and are more expensive to manufacture.

So the tradeoff is a few percent efficiency for a lot more ease in manufacture, lower cost and lower weight. You might get a more efficient motor going synchronous, but the vehicle as a whole loses fitness.
=Smidge=

 

[qwk]

I'm pretty sure that Tesla isn't going to go backward in motor technology.

Backward? Synchronous machines should allow for a more efficient drivetrain than can be achieved using an induction machine.

Yes, it is absolutely going backward. "Efficiency" is used too loosely in marketing. There is "peak" efficiency, and there is the area under the entire curve called " average efficiency ". A Peak efficiency number can look good, and grab attention just like a peak horsepower number off of a dyno sheet. It isn't until you look at the area under the entire curve, before one can come to any kind of conclusion.

What most people don't realize is that an induction motor can have a bit better average efficiency(we are talking about small differences here, as most electric motors are very efficient). One of the main benefits of an EV using an induction motor that's often not mentioned, is the ability to have a very high performance vehicle that gets the same mpge as a totally gutless EV. Why would anyone build and drive the latter? The answer is- battery cost. As I stated in earlier posts here, an EV's performance is directly tied to it's battery output. A good example of this is the Tesla drivetrain in the Rav4 ev. It used the same motor as the Performance Model S, yet is only capable of about 1/2 of the power due to the smaller battery.

Tesla's motors and drivetrain are so much superior to any other from an engineering perspective, it's sad really. If you need proof, just look at the pictures if the inside of a Tesla motor vs Spark or leaf motor. One looks like a meticulous work of art, the others like an old Chrysler alternator from the 70's.

 

[RegGuheert]

Tesla's motors and drivetrain are so much superior to any other from an engineering perspective, it's sad really. If you need proof, just look at the pictures if the inside of a Tesla motor vs Spark or leaf motor. One looks like a meticulous work of art, the others like an old Chrysler alternator from the 70's.

No need for art, but hard data would be nice. Here are the powertrain efficiency curves for the 2011 LEAF (from the February 2011 issue of Vehicle Electrification, page 17:

If you have a similar curve from the Model S or any other EV, we can compare their efficiencies.

 

[GRA]

1. How fast will Combo chargers be rolled out? CHaDeMo doesn't have insurmountable lead in U.S., perhaps no more than 200 total currently and considerably less in California and Oregon. Combo could easily catch up, especially if GM/BMW/VW/Ford install at dealerships ala Nissan, or NRG etc. install dual-standard chargers. Assuming $100k/charger installed and operational, 200 is only $20 million.
2. Is it possible to make an inexpensive CHaDeMo-Combo adapter?

There is absolutely no way that these companies supporting Frankenplug, but rolling out compliance cars, are going to spend one penny on charging infrastructure. Only Tesla and Nissan are doing that, and it's no surprise that they are 60,000 sales, 2500 DC chargers and many years ahead of ALL the Frankenplug companies COMBINED.

Unless you are ponying up "only $20 million", I'll suggest that is real money. NRG will provide 200 Frankenplug chargers along side CHAdeMO chargers over 4 years in California only when several criteria are met. Otherwise, it will be CHAdeMO only.

That's the only "for sure" deal. These companies will be digging deep with political favors to get tax money to fund a nationwide system, and helping regulators craft rules that favor their "national" standard for all the foreign companies that need to sell compliance cars here.

I guess we'll see, Tony. After all, it took Nissan 28 months of Leaf sales before they installed the first Nissan paid-for CHAdeMO at a dealer; maybe the other guys will be smarter. But $20 million, compared to the cost of developing these cars and putting them into production, is chicken feed. BTW, AFAIA neither BMW or VW is required to roll out compliance cars, only the top six in sales (Toyota/Honda/Nissan/GM/Ford/Chrysler).

The fact that there are 2500 total CHAdeMo in the world falls into the who cares? category for me, and I imagine the same is true for virtually all U.S. CHAdeMo-equipped BEV drivers, as they have no intention of shipping their cars out of the country. The only ones that matter are those we can use. Right now, the number of CHAdeMOs in Norcal that would be of any use to me are in the single digits. Only three of the nine that Nissan just announced in Norcal would add any utility or redundancy for me, and even though we're the biggest PEV market in the country there's less than 30 total, so there's hardly a big hurdle for the Combo chargers to overcome.

 

[qwk]

If you have a similar curve from the Model S or any other EV, we can compare their efficiencies.

Unfortunately Tesla doesn't make much technical information available to the public. Comparing the mpge of the leaf vs roadster is as close as it gets. Roadster is 120 mpge, Leaf is 115 mpge. I know that the roadster is smaller, and a few hundred pounds lighter, but it shows what an induction motor with over twice the power can accomplish. Cost aside, just taking the technology into consideration, I know what I would want to drive.

 

[Nashco]

No need for art, but hard data would be nice.

Data, what a concept! Thank you for bringing some sense to the thread. I'm done responding to the useless ridicule and harassment, but hopefully there are others out there that would like to discuss actual facts about the car.

Here are some very interesting plots that were recently published at the 2013 SAE EV symposium. These show the performance and efficiency plots of the Spark EV powertrain. Note that the powertrain uses a 3.17 ratio planetary gear reduction, and the efficiency plot is for the entire powertrain (from DC bus to axle output.

Efficiency plot

Performance curves

Here's an interesting video on the powertrain layout and gearing design:

http://on.aol.com/video/chevy-spark-ev-powertrain-animation-517746616" onclick="window.open(this.href);return false;

And some very high resolution pictures of the powertrain assembly:

http://www.gmgoelectric.com/product/public/us/en/electrification/drive.html" onclick="window.open(this.href);return false;

Bryce

 

[Stoaty]

Here are the powertrain efficiency curves for the 2011 LEAF (from the February 2011 issue of Vehicle Electrification, page 17:

Added to Wiki under Drivetrain section:

http://www.mynissanleaf.com/wiki/index.php?title=Drivetrain" onclick="window.open(this.href);return false;

 

[TonyWilliams]

... the Spark EV powertrain. Note that the powertrain uses a 3.17 ratio planetary gear reduction

Well, that certainly explains the 400 ft/lbs of torque. So the motor turn a bit less than half the speed of the LEAF motor at the same speed with slightly less more than double the 2013 LEAF torque (and slightly less than double for the 2011-2012 LEAF).

 

[TonyWilliams]

... The only ones that matter are those we can use. Right now, the number of CHAdeMOs in Norcal that would be of any use to me are in the single digits. Only three of the nine that Nissan just announced in Norcal would add any utility or redundancy for me, and even though we're the biggest PEV market in the country there's less than 30 total, so there's hardly a big hurdle for the Combo chargers to overcome.

If it was so difficult and time consuming with CHAdeMO, why on earth would you think a different, new standard would be anything different? It's not the fact that one unit is isolated or non-isolated, or one unit is PLC or CAN bus.

April 2013 DC quick chargers (CHAdeMO and Tesla). There are no Frankenplugs:

 

[TonyWilliams]

"The Chevrolet Spark EV is getting closer to launch, and the closer we get, the more details GM is releasing. However, there have been some conflicting reports and misleading information that’s been reported. Thanks to our friends at Inside EVs, they took the time to set the record straight."

"For example, one spec on the Spark EV is the torque rating of 400lb-ft. That would be more than 100 lb-ft more than the Tesla Roadster, but if we dig deeper we realize the 400 comes from the measurement after the torque reduction gear, not the direct motor measurement. The electric motor in the Spark electric vehicle will likely be around the 150lb-ft to 175 lb-ft mark."

"Equally confusing is the battery capacity. The 2014 Spark EV website says 20kWh, but GM press releases are still saying 21 kWh."

"The SAE combo quick charger is an optional feature, but the website says “Late Availability” and specifies compatible stations won’t be around until late 2013. We have no idea what late availability means."

"Availability is still a little bit confusing. Back in March, GM specifically said the Spark EV would “be in dealerships by July if all goes to plan.” Now, Chevy’s website says “In limited quantities late 2013.” That leads us to guess something hasn’t gone according to plan? Or does July qualify as late 2013 since it is the first month in the second half of the year?"

 

[TonyWilliams]

... fifteen minutes of manual winding seem like an awful lot for a mass-produced product. I doubt the LEAF motor has that much manual labor involved, based on the YouTube videos I has seen, but perhaps there is a lot more that is not seen.

Ya, that was 15 minutes to set it up... each one. I guess that's still 4 per hour, or 32 per shift max with no breaks. I suspect that will build all the motors they need to comply with California rules in the next three years. Everything above that is gravy!!!

 

[Deleted member 8423]

"Availability is still a little bit confusing. Back in March, GM specifically said the Spark EV would “be in dealerships by July if all goes to plan.” Now, Chevy’s website says “In limited quantities late 2013.” That leads us to guess something hasn’t gone according to plan? Or does July qualify as late 2013 since it is the first month in the second half of the year?"

Yeah, because a product release has never been delayed before. If it were, doesn't seem like a surprise that they wouldn't want to make a big deal out of it. Maybe they have to hold back on the release because there won't be an SAE DCFC infrastructure available until later this year.

http://www.chevrolet.com/" onclick="window.open(this.href);return false; - click cars, click spark, click spark EV - You'll see the picture with the original caption (late Summer 2013)

http://www.chevrolet.com/spark-ev-electric-vehicle.html" onclick="window.open(this.href);return false; - Says "Late 2013"

So even the Chevy website can't completely agree on the date.

 

[RegGuheert]

Nevermind.

 

[RegGuheert]

Here are some very interesting plots that were recently published at the 2013 SAE EV symposium. These show the performance and efficiency plots of the Spark EV powertrain. Note that the powertrain uses a 3.17 ratio planetary gear reduction, and the efficiency plot is for the entire powertrain (from DC bus to axle output.

Efficiency plot

Thanks for the data! In spite of the claim in the magazine that the curves I posted were for the entire LEAF powertrain, I have to wonder if that is true, given that the axes are "Motor Torque" and "Motor Speed".

Performance curves

It seems clear from looking at these curves that the Spark EV has LESS torque at the axle than the 2011 LEAF. The LEAF has 280 Nm at the motor which equates to 2222 Nm at the axle after the 7.9377 reduction gear. That's 1622 ft*lbf of torque at the axle! This compares with 1700 Nm (at the axle) for the Spark EV. Clearly the 400 ft*lbf spec for the Spark EV is the motor torque.

But the difference is in power. The LEAF can only maintain its maximum torque up to about 25 MPH, while the Spark EV can (nearly) maintain it up to about 40 MPH. At 40 MPH, the LEAF is down to somewhere around 1350 Nm of torque.

 

[scottf200]

This is not your fathers electric motor:

 

[GRA]

... The only ones that matter are those we can use. Right now, the number of CHAdeMOs in Norcal that would be of any use to me are in the single digits. Only three of the nine that Nissan just announced in Norcal would add any utility or redundancy for me, and even though we're the biggest PEV market in the country there's less than 30 total, so there's hardly a big hurdle for the Combo chargers to overcome.

If it was so difficult and time consuming with CHAdeMO, why on earth would you think a different, new standard would be anything different? It's not the fact that one unit is isolated or non-isolated, or one unit is PLC or CAN bus.

Because most of the 'difficulty' as far as Nissan putting any in themselves was due to when they decided to do it, not technical factors. After all, Tesla has amply demonstrated that it can be done far faster, and with a tiny fraction of the financial resources available to Nissan/Mitsubishi or a single member of the SAE consortium members, let alone a group of them.

April 2013 DC quick chargers (CHAdeMO and Tesla). There are no Frankenplugs:

Uh huh, and of those chargers, there are only three or four that would be really useful to me living in the East Bay a dozen miles or so north of "dreary Fremont" (copyright 2013 by Tony Williams), to allow the Leaf to be used for out-of town trips: Fairfax (Pt. Reyes), Concord (Sacramento), Vacaville (ditto), and Elk Grove (Sac and/or South Tahoe, with an intermediate stop). San Ramon would be an emergency stop only for me, coming back. The QC shown on the Plugshare map in Folsom is a Tesla Supercharger, and although it would be nice to have a CHAdeMo there, it would be more useful to have one in Placerville (and Auburn or better yet Colfax), so the Sacramento Leafers can get to Tahoe in a reasonable amount of time.

If I traveled 101 North frequently Petaluma and Santa Rosa would be useful, and if I lived in the City or the South Bay the ones around San Mateo and Redwood City would be useful, or (San Mateo) for trips to Half Moon Bay. Stevens Creek Nissan is better than nothing for people going to/from Santa Cruz, but Campbell or better yet Los Gatos is superior. But after Vacaville, what's been the single most requested location by Bay Area Leafers for a QC? Gilroy (the one shown on the Plugshare map is another Tesla Supercharger), to allow day and weekend trips to Monterey/Carmel and even Big Sur from the Bay Area. Putting one in Salinas wouldn't be a bad idea either.

Fremont could be useful to others transiting 880/101S- the one on Capitol Expressway in San Jose isn't too far off 101/280/85 to handle that traffic. But adding even more QCs to the South Peninsula and South Bay is overkill; It seems like most people don't want them where we live, we want them on the corridors (80/580/680/101/17/1) out of town at appropriate distances to allow use of most of the battery capacity before charging.

Combine the lack of well-chosen sites with the fact that most if not all of the Nissan dealer QCs are open business hours only, and perhaps some will be restricted to customers only as may be the case with some of the SoCal dealerships, and their usefulness would be limited for many people.

So, all of this leaves lots of room for a smart company or companies to make up plenty of time on CHAdeMo with SAE, as Tesla has demonstrated can be done with their (mostly) intelligently-placed Superchargers, avoiding most of the CHAdeMo missteps. It won't be a fast process, but it doesn't have to be the glacially-paced one we've experienced with CHAdeMo to date; GM could choose to roll out an initial QC network at the same time they release the Spark EV. And if not them, maybe BMW will be more intelligent; after all, their customer demographic is a lot closer to Tesla's than GM's is, and Tesla has stolen far more business from BMW than they have GM, so maybe BMW will chose to emulate Tesla rather than Nissan.

To be sure, Tesla doesn't need as many QC locations owing to their greater range, but unlike Tesla no one is pretending that 'affordable' BEVs are currently suitable for extended road trips. Most owners would be happy to have QCs located that allow them to make regional intercity and day/weekend trips. I think a ring of a dozen or even a half dozen QCs at say 50 mile radius around each of the four major California metropolitan areas would have a significant effect, although rings spaced at 25 mile intervals would be preferable. _You_ know how important that can be - look at the effect of just that single intelligently-chosen QC location in San Juan Capistrano - it makes trips between LA and SD practical. So, if I were dictating where to put an initial batch of a half-dozen for the Bay Area, I'd put them in San Rafael (101/580); Fairfield (Cordelia Junction, 80/680/12W) or Vacaville (80/505); Dublin/Pleasanton (580/680); Gilroy (101/152); San Mateo (101/92); and maybe one in Oakland/Emeryville (80/880/580) or else Los Gatos (85/17) or Santa Cruz (1/17), and then expand/infill from there. Not that the consortium members would need to do it all themselves, I'm thinking of the intial six or twelve as seed. And certainly charging shouldn't be free.