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There i a remarkably detailed 60 page online printable magazine covering the entire story of the Volt. Sort of like compressing the 1500 posts on GM-Volt.com into one concise magazine.

You can view it and print it for free here:

http://www.nxtbook.com/nxtbooks/sae...442344144344633373441453033413937384646463337

It was written and edited by Lindsay Brooke who is a highly acclaimed automotive engineering writer.
 

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I'd have thought that this would generate a lot of discussion. Where are the comments?
 

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Hi guys.

It will take some time to read this manuscript but I am sure it will be a very interesting story when I get the time.

Take Care,
TED
 

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Well Tag I had to read it first and while we all know a lot of it there are still some very interesting parts. I especially liked the section "Engineering with Maniacal Focus", p26 and 27. I can relate to the pressure the team was under to solve what seemed unsolvable within the tight schedule. Like: "After the 40 month development program, the main thing the engineers really wanted to do was take a vacation as they had not one for such a long time". Another part that was interesting (in the same section) was "Solving the BSE Riddle", BSE is the battery state estimator program. "There were times when the team thought they were up against the wall".

The other good part was in the battery development section. Apparently A123 put up a good fight and it was almost 50/50 on who would take the contract. I have a suspicion that A123 may still be in the game and indeed be a Gen2 supplier of an improved battery---ie one that does the job with a higher DOD and therefore offers lower cost and weight.

Thanks for the Article Lyle, enjoyable reading indeed.

I'm surprised the Volt is only 42, 000$. It's got a lot more high tech in it than that.
 

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Hi Tag,

What I was amazed about was that GM collaborated with so many companies and industries. I haven't finished reading the final pages but have this link bookmarketed for future re-reading. My memory is like a sive; I need to read something over several times for it to sink in;)
 

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Lyle, This was a very interesting series of stories. Sure points out the complexities of the whole development process. Thanks again for all you do for us and I am sure I will post more to the owners blog once I get my Volt in March.

Take Care, TED
 

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Some reference information for you all about this ...

This publication was produced by the SAE (Society of Automotive Engineers). Their EV subsite is at ev.sae.org (also evsae.com ), where they appear to have several of these articles in regular web form. The link that Lyle provided is to their online, Flash-based document viewer. I looked around for a way to get a hardcopy (I'll pay for it!) but haven't found it yet.

You CAN download this as a regular PDF, however it takes a little effort:
1. Go to the document viewer link that Lyle provided.
2. In the upper right corner, click on the "Save" icon (the floppy disk).
3. On the resulting web page, scroll down past the AIR installer stuff and click on the link to "download PDF version".
4. You will get a ZIP file. The PDF is inside that ZIP.

Edit: Per CalCars, you can get to the PDF directly via this link (PDF is inside the ZIP file):
http://pages.nxtbook.com/nxtbooks/sae/10EVSD1104/offline/sae_10EVSD1104_pdf.zip

I noticed from the masthead on page 3 that this is "Volume 1, Number 1" of the publication, so I'm glad to hear I haven't been missing out :) At the very end, on page 60, they have a brief discussion of the new publication and ev.sae.org, and mention that their publishing schedule for 2011 calls for new issues on Feb 23, May 25, Aug 24 and Nov 30.

I'm afraid I'm going to have to kill some trees printing this out at work. Double sided!
 

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Noticed a few things that aren't quite accurate:

pg 14 - 9.4 kwh rating vs. 10.4
pgs 14 & 17 - SULEV CARB rating vs. ULEV
pg 15 - 10,000 MY 2011 vs. 15,000?
pg 21 - currents create internal resistance, which causes significant warming of the cells
pg 35 - But in a few narrow operating conditions, typically accelerating from 70 mph (113 km/h) while in extended-range mode, the shaft speed of the 111-kW traction motor begins to exceed its peak efficiency. So the system’s designers took advantage of the more direct and efficient mechanical connection to the car’s wheels offered by coupling the generator and ring gear. In doing so, the generator brings the traction motor’s shaft speed down to a more optimum rpm.

Otherwise a great read.
 

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Good eye ChuckR. Currents don't really create internal resistance. It's there even at zero current (you just can't tell).

What was wrong w/ the statement on p35??
 

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Well Tag I had to read it first and while we all know a lot of it there are still some very interesting parts. I especially liked the section "Engineering with Maniacal Focus", p26 and 27. I can relate to the pressure the team was under to solve what seemed unsolvable within the tight schedule. Like: "After the 40 month development program, the main thing the engineers really wanted to do was take a vacation as they had not one for such a long time". Another part that was interesting (in the same section) was "Solving the BSE Riddle", BSE is the battery state estimator program. "There were times when the team thought they were up against the wall".

The other good part was in the battery development section. Apparently A123 put up a good fight and it was almost 50/50 on who would take the contract. I have a suspicion that A123 may still be in the game and indeed be a Gen2 supplier of an improved battery---ie one that does the job with a higher DOD and therefore offers lower cost and weight.

Thanks for the Article Lyle, enjoyable reading indeed.

I'm surprised the Volt is only 42, 000$. It's got a lot more high tech in it than that.
Being able to use a smaller battery would certainly be a big advantage for A123. The clincher might be if they could also do away with liquid coolant and get by with active air. A123 should also have a power advantage which might come into play for a Voltec Converj, MPV, minivan, midsized Buick, or small pickup. It doesn't get much attention, but I think the ability to effectively use air for thermal management will be a big step forward.
 

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The 70+ mph number is where both motors operate in parallel in EV mode to reduce speed and increase efficiency of the traction motor. We've been told that in ER mode the engine may provide torque to the wheels anywhere above 30 mph, depending on efficiency mapping.
 

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Printed it out today. Excellent coverage. I especially like that they name the heroes who made this car a reality - photos with name and title.

The articles are very dense with info, yet at 60+ pages, it just scratches the surface.

I like that they leveraged so much of what they already had to reduce risk. It also implies that Gen 2 may be radically improved with better range extender, batteries, reduced weight, etc.
 

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I'm about 2/3 of the way through the article now. I'm surprised this isn't the main topic for discussion on the home page. This article summarizes the technical content that we've been discussing for years now on this site. Should be a must read for newbies and more seasoned visitors alike.
 

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Noticed a few things that aren't quite accurate:

pg 21 - The currents create internal resistance, which causes significant warming of the cells
This is kind of ambiguous, but it is right. When you have a large current drain in a battery system you are effectively changing the internal resistance of the battery. And at a high current load that internal resistance will generate a lot of heat. So in fewer words, he was trying to get across that when you have high drain situations (passing, WOT), the resistance inside the cells will change, and this gives rise to a non-linear heat generation.



this would be correct for a linear resistance, however when there is a non-linear resistance response from the circuit we get:



The scope of the document is not to overwhelm one with technical jargon and concepts, but reinforce the development and how problems were overcome.


Noticed a few things that aren't quite accurate:

pg 36 - But in a few narrow operating conditions, typically accelerating from 70 mph (113 km/h) while in extended-range mode, the shaft speed of the 111-kW traction motor begins to exceed its peak efficiency. So the system’s designers took advantage of the more direct and efficient mechanical connection to the car’s wheels offered by coupling the generator and ring gear. In doing so, the generator brings the traction motor’s shaft speed down to a more optimum rpm.

Otherwise a great read.

This is also correct. The Volt has 3 clutches that can activate to increase efficiency. A clutch from generator to traction motor, generator to ICE, and generator to ring gear. When the car is in CS mode the second clutch will activate to charge the car in most normal conditions. However when the traction motor gets outside of its peak efficiency then can do a few things. Activate the third clutch and the first clutch, which couples the traction motor and generator motor. This brings the motor RPM down and increases efficiency. When in CS mode the car can activate the second clutch to recharge, and/or activate all three (from what I know), thus giving the reduced RPM of the traction motor and using the 10-15% more efficient mechanical connection.
 

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Hey ColinSummers, you posted elsewhere (not at this site) that you wished you could get a PDF of this publication so you could read it on your tablet. I posted instructions on getting the PDF here:

http://gm-volt.com/forum/showthread...-Story-Free-Online-Magazine&p=45645#post45645

The other site requires login so I couldn't post this comment there, and your profile here doesn't allow for personal messages, so I'm calling you out here with this public comment :)
 

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capn

My original post noted some statements that I said weren't "quite accurate" without being specific.

pg 21 - Current does not "create" (change maybe) internal resistance. Current through a resistance creates heat, and resistance will increase with temperature. The cooling system will disapate the heat and resistance will decrease, but it would not be "quite accurate" to say that the cooling system "destroys" resistance.

pg 36 - "But in a few narrow operating conditions, typically accelerating from 70 mph (113 km/h) while in extended-range mode the shaft speed of the 111-kW traction motor begins to exceed its peak efficiency."

The The 70+ mph number is where both motors operate in parallel in EV mode to reduce speed and increase efficiency of the traction motor. In ER mode the engine may provide torque to the wheels anywhere above 30 mph, depending on efficiency mapping.

Law of Logical Argument: Anything is possible if you don't know what you are talking about.

I'm a retired EE and do know a little about what I am talking about.
 

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Not to pile on, but I think the SAE phrasing is just fine. Strained use of current and resistance, sure, but what they mean is clear and it's all generally accurate.

- a future retired EE :)
 

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Sorry. My wife says I’m kinda anal.
The SAE statement was “The currents create internal resistance, which causes significant warming of the cells.” If it had said “The currents cause significant warming of the cells”, I would not have said it wasn’t quite accurate.
Guess I'm a frustrated editor. If SAE is listening I’m available for work at home.
 

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capn

My original post noted some statements that I said weren't "quite accurate" without being specific.

pg 21 - Current does not "create" (change maybe) internal resistance. Current through a resistance creates heat, and resistance will increase with temperature. The cooling system will disapate the heat and resistance will decrease, but it would not be "quite accurate" to say that the cooling system "destroys" resistance.

pg 36 - "But in a few narrow operating conditions, typically accelerating from 70 mph (113 km/h) while in extended-range mode the shaft speed of the 111-kW traction motor begins to exceed its peak efficiency."

The The 70+ mph number is where both motors operate in parallel in EV mode to reduce speed and increase efficiency of the traction motor. In ER mode the engine may provide torque to the wheels anywhere above 30 mph, depending on efficiency mapping.

Law of Logical Argument: Anything is possible if you don't know what you are talking about.

I'm a retired EE and do know a little about what I am talking about.
Ok, I guess I should read between the lines a little. I assumed "not quite accurate" was synonomous with wrong.

Good to know! Well That is what I know of electricity, MEs really only cover one course on the subject. So I guess I will defer to your expertise on those matters. :)
 
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