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Devils advocating...from someone who shorted TSLA

JRP3

Hyperactive Member
Aug 20, 2007
22,681
59,640
Central New York
Could you please cite this fact. I've read it before but can't find anything from Tesla confirming 2-3000 cycles.
http://www.embedded-world.eu/fileadmin/user_upload/pdf/batterie2011/Sonnemann_Panasonic.pdf
Page 20 in this PDF from Panasonic in 2010 shows full cycling from 4.2V to 2.5V out to 2600 cycles with around 25% of capacity loss. Obviously cycles in the Model S would not be to such extreme SOC levels on either the top or bottom and would provide many more cycles with even less capacity loss.

Here is a shallow cycle graph showing around 15% capacity loss out to 3000 cycles: http://ma.ecsdl.org/content/MA2011-02/17/1282.full.pdf
I thinks it's safe to say Tesla does not have a battery durability issue.
 
Last edited:

30seconds

Active Member
Feb 28, 2013
2,389
6,334
SF
based on that curve we should see reports of 10% loss after 200 full cycles if Tesla's battery management provides no improvement over the raw cells. Since I doubt anyone is going through full cycles on a daily basis it may take a year or two, but at least gives a way to measure. Of course if this is the decay curve then it may take the vast majority of drivers a decade to see 20% loss.
 
ANd here is where electric diverges from all the other alternative fuel concepts. The infrastructure buildout is trivial. To put a fast charge station every 50 MILES across our ENTIRE Interstate Highway system is about 1150 charge stations. If they each cost a million dollars, and at that price we are talking solar panels, huge reserve battery arrays, and upscale convenience stores for Ho'Ho's and Ding Dong's and the famous Bloomberg Big Gulp, it's 1.1 BILLION. Add up all the sour money at Enerdel, Think, Azure Dynamics, A123 and Fisker. They could have ALREADY DONE IT. For what they squandered like drunken ho's and sailors.
...
Jack Rickard

That's a little more that the cost of adding ONE lane to each barrel of I-93, here in NH, from Salem to Manchester. One, comparatively small, highway construction project that costs the same as a complete rollout of electric charge stations. I just wanted to put that out there for a sense of scale.

Oh - and I still have a stack of Boardwatch magazines in my basement somewhere :)
 
Jack, great post but one correction here:

Technically, there IS a little bit of a problem long term. The cells they use in the car are ultimately designed for consumer use. Flashlights. Cameras. RC toys. Smoke alarms. Thermostats. There really is no impetus to make them long lasting vis a vis cycle life.

They WERE rated at about 800 cycles. With the advent of the automotive application, they have simply REMOVED cycle life from the data sheets. Vague references to longer cycle life. Mumble, mumble.

The cells they use in the car are actually designed for automotive use. Tesla and Panasonic have jointly tweaked the chemistry for automotive applications. It's a proprietary formulation and why you won't find a data sheet on them. The only thing they share in common with the cells designed for consumer use is form factor and the machinery used by Panasonic to manufacture the cells.

Source:
Tesla Motors CTO talks future batteries and charging protocols
SAE International, 12-Mar-2013
We use a nickel-cobalt-aluminum (LiNiCoAlO2) lithium-ion chemistry for our battery cathode material. We don’t use a titanate, which has about half the energy density but is generally good at high charge rates. Some start-ups are using metal oxides; we fall broadly in that category. At this point we really have heavily customized that cell. We’ve totally custom-engineered that cell working jointly with Panasonic to create. It’s an automotive cell, tested to automotive standards. It doesn’t go into laptops anywhere. What keeps us in that general shape and size is the production and cost efficiency. We’re seeing price points that none of the larger-format cells are able to meet.
 

stopcrazypp

Well-Known Member
Dec 8, 2007
12,667
8,563
The cells they use in the car are actually designed for automotive use.
Actually as I said in the other thread, I think the optimizations will be in C-rate, not cycle life. The standard "consumer" NCR18650A are tested to 500 cycles (100%DOD, 0.5C charge, 1C discharge).

The Roadster uses a smaller 2%-95% SOC window, Models S will likely use something similar.
http://www.teslamotors.com/blog/bit-about-batteries

500 cycles in those conditions already good for 120k EPA miles for the 85kWh, 90k for the 60kWh (I'm factoring in ongoing degradation by using a trapezoid approximation of the area under the graph, plus factoring also the smaller SOC window). There's still 74.7% capacity at that point (based on 3000mAh full capacity, given it reaches that point in the first 5 cycles). If you extrapolate the degradation from the second part of the graph it works out to 860 cycles to 70% capacity. This is 190k EPA miles for 85kWh, 150k for 60kWh.
http://industrial.panasonic.com/www-data/pdf2/ACI4000/ACI4000CE25.pdf

Given real world conditions on the pack will be more mild (smaller SOC window, lower average charge rate, much lower average discharge rate) there is no need to optimize the cycle life as even the consumer cells will perform well in the application. Certainly much better than the "automotive" cells in Leaf is faring without temperature management.
 
http://www.embedded-world.eu/fileadmin/user_upload/pdf/batterie2011/Sonnemann_Panasonic.pdf
Page 20 in this PDF from Panasonic in 2010 shows full cycling from 4.2V to 2.5V out to 2600 cycles with around 25% of capacity loss. Obviously cycles in the Model S would not be to such extreme SOC levels on either the top or bottom and would provide many more cycles with even less capacity loss.

Here is a shallow cycle graph showing around 15% capacity loss out to 3000 cycles: http://ma.ecsdl.org/content/MA2011-02/17/1282.full.pdf
I thinks it's safe to say Tesla does not have a battery durability issue.

The document you cite shows the 80% capacity level as low as 600 cycles. 80% is the level customarily cited in life cycle testing. It is true it does flatten out a bit after that. But 70% is pretty much a substantial decrease in range.

The second reference is for an entirely different 400 mAh cell they are studying for EV battery packs. A white paper on what could be done.

Jack Rickard

- - - Updated - - -

So you are "correcting me" on this topic with a vague corporate party line bloat about secret sauce and their "joint" design with Panasonic. I've kind of drunk the koolaid myself but I'm not going for all of that....


Jack Rickard

- - - Updated - - -

Sorry, but this is totally wrong. The 800 cycles you were refering to is for non-managed application in consumer devices. The major factor in battery aging is temperature, particularly when battery charged/discharged. The Tesla MS batteries have state of the art software based proprietory temperature control and charging current control. The battery also is not discharged fully as with the consumer applications. Lower Depth of Discharge (DOD) for great majority of MS daily usage yields lower battery stress and improved longevity. Alltogether the battery in MS will exceed 2,000 to 3,000 cycles with less than 20% capacity degradation. Conservatively assuming 200 miles range this results in 400,000 to 600,000 miles. MS has essentially a lifetime battery.

You're sorry? Totally wrong?

I'm sorry. You're totally wrong.

Now that we have that out of the way, see the Tesla SEC filings earlier this year. They specifically contradict the koolaid you have apparently quaffed. Why are they talking about 65-70% capacity in five to seven years as being an identified risk factor?

Its ok to lie on press releases and in blogs. It's kind of dimly viewed in SEC filings.

Jack Rickard
 

BriansTesla

Old school meets new tech
May 8, 2012
312
533
AI WA
The document you cite shows the 80% capacity level as low as 600 cycles. 80% is the level customarily cited in life cycle testing. It is true it does flatten out a bit after that. But 70% is pretty much a substantial decrease in range.

**snipped**

Now that we have that out of the way, see the Tesla SEC filings earlier this year. They specifically contradict the koolaid you have apparently quaffed. Why are they talking about 65-70% capacity in five to seven years as being an identified risk factor?

Its ok to lie on press releases and in blogs. It's kind of dimly viewed in SEC filings.

Jack Rickard

Please check this report that was presented at TESLIVE by Tom Saxton.

"Battery packs in Tesla Motors’ Roadster electric cars will retain an average of 80- to 85-percent of capacity after 100,000 miles driven"
 

Doug_G

Lead Moderator
Global Moderator
Apr 2, 2010
17,888
3,412
Ottawa, Canada
Why are they talking about 65-70% capacity in five to seven years as being an identified risk factor?

They are required in the "risks" section to be extraordinarily conservative.

The report by Tom Saxton of Plug-in America puts that one to bed. Even the older Roadster technology is lasting substantially longer than Tesla promised.
 

JRP3

Hyperactive Member
Aug 20, 2007
22,681
59,640
Central New York
The document you cite shows the 80% capacity level as low as 600 cycles. 80% is the level customarily cited in life cycle testing. It is true it does flatten out a bit after that. But 70% is pretty much a substantial decrease in range.
It's also true that 80% holds out to at least 1000 cycles on that chart, so picking the worst case point on the line doesn't really prove much. 70% doesn't show up until 2600 cycles, rather a bit different than you are implying.
The second reference is for an entirely different 400 mAh cell they are studying for EV battery packs. A white paper on what could be done.

Jack Rickard

- - - Updated - - -

So you are "correcting me" on this topic with a vague corporate party line bloat about secret sauce and their "joint" design with Panasonic. I've kind of drunk the koolaid myself but I'm not going for all of that....


Jack Rickard

- - - Updated - - -



You're sorry? Totally wrong?

I'm sorry. You're totally wrong.

Now that we have that out of the way, see the Tesla SEC filings earlier this year. They specifically contradict the koolaid you have apparently quaffed. Why are they talking about 65-70% capacity in five to seven years as being an identified risk factor?

Its ok to lie on press releases and in blogs. It's kind of dimly viewed in SEC filings.

Jack Rickard
The SEC filings are worst case scenario, as you know. Even using the 80% capacity at 600 cycles number, and using an average of 240 miles of range for the Model S 85, that's still 144,000 miles of range. How likely is it that anyone would be doing full discharge cycles like that to accumulate enough mileage to actually see the 65-70% capacity mentioned in the SEC filing? Bottom line, do you think, or do you have any evidence, that Tesla has a battery pack cycle life issue?
 

techmaven

Active Member
Feb 27, 2013
3,618
9,768
The document you cite shows the 80% capacity level as low as 600 cycles. 80% is the level customarily cited in life cycle testing. It is true it does flatten out a bit after that. But 70% is pretty much a substantial decrease in range.

The second reference is for an entirely different 400 mAh cell they are studying for EV battery packs. A white paper on what could be done.

There are several graphs. It would be helpful if you pointed out which one you are referencing. The first reference, the Panasonic D&E Forum 2011 has mostly 100% DOD charts. The NCR18650 cycle performance chart for example is a 100% DOD chart and has the roughly 80% capacity at 600 cycle data point. The cycle durability test in that one also shows roughly the same, but it does show that there is usable capacity at 25 degrees C out to 2000 cycles at roughly 75% capacity. That alone was huge, as it meant that one could have far higher life span if one was ok with roughly 25% capacity loss. Basically, the curve flattens out dramatically.

Until we found the 2nd reference, it was hard to quantify the gains given when one didn't cycle to 100% DOD. We had charts showing the effect of temperature on capacity loss in both cold and hot, we had high discharge, but we didn't really have charts showing limited DOD with high cycles and high charge/discharge rates. This second reference shows that. It uses the same cathode chemistry as what goes into the Model S and is tested with 18650 cylindrical cells. Not only does it show that limiting DOD dramatically limits the capacity loss (less than 20%) out through 3,000 cycles, it shows that it can have such capacity retention even with high charge and discharge rates. Now, a real world Model S will still have higher discharge rates, but lower charge rates and the vast majority of vehicles will have far less DOD. This second chart shows why Tesla can offer unlimited mileage warranty on the 85kWh battery pack.

3,000 cycles at a very conservative 100 miles per cycle is 300,000 miles. It still isn't' clear how many very small DOD cycles relates to a full charge cycle. Let's just say for a moment that worst case scenario is that every day is a full charge cycle. For 3,000 cycles, that 8.22 years. Obviously, it doesn't just drop off a cliff at 3,000 cycles. But let's just say it's a hard stop at 3,000 cycles. If you drive 150 miles a day each and every day of the year in a 85kWh Model S, you won't be at 100% DOD. That's 450,000 miles in 8.22 years or roughly 55,000 miles a year. What I don't know is if you drive 75 miles a day each and every day, if that also counts as the same kind of cycle every other day. In other words, just because you can drive 450,000 miles in 8 years doesn't mean it will achieve 450,000 miles of life in 16 years. We don't have good data on the absolute longevity in terms of decades.
 
Well guys, for the moment it is over. I closed my short yesterday at 134. Not the best trade I made.

I have not changed my opinion but there is no sense fighting market insanity.

Still, the collapse is certain. I will return to this stage.

If the collapse certain, wouldn't the real insanity be covering your short?

Separately, does lower wait times imply lower order rates for the Model S? We are seeing times from finalize to delivery hit 3-4 weeks. Less a week for transport, less 5-7 days for production, leaves ~ 2 weeks of true "wait time". Once backlog orders (Europe + US stragglers) are produced, that "wait time" vs. production rate should be a good proxy for demand rate, right?

It will be interesting to see if US wait times increase as Tesla focuses on the 2-3k of Europe orders.
 

MikeC

Active Member
Supporting Member
Jul 9, 2012
3,330
10,993
Los Angeles
Well guys, for the moment it is over. I closed my short yesterday at 134. Not the best trade I made.

I have not changed my opinion but there is no sense fighting market insanity.

Still, the collapse is certain. I will return to this stage.

Even though you're on the other side, I have to say I respect you for posting here and being honest. I'm glad you got out before it got any worse for you.
 

Blurry_Eyed

MS Sig #267, MX Sig # 761
Dec 29, 2011
588
308
If the collapse certain, wouldn't the real insanity be covering your short?

Separately, does lower wait times imply lower order rates for the Model S? We are seeing times from finalize to delivery hit 3-4 weeks. Less a week for transport, less 5-7 days for production, leaves ~ 2 weeks of true "wait time". Once backlog orders (Europe + US stragglers) are produced, that "wait time" vs. production rate should be a good proxy for demand rate, right?

It will be interesting to see if US wait times increase as Tesla focuses on the 2-3k of Europe orders.

This is speculation based on a post I saw here on the forum, I haven't tried to find the relevant post to link to though. If you are good with the search function here, I think you could find it.

From what I recall the poster indicated that the factory would be focusing on producing more European cars in the near future. When that switch over occurred, the U.S. wait times might push out to 3 to 5 months for a time as the European backlog is filled. I don't know if this is true, but it could be possible to see U.S. wait times start to push out significantly for a period coming up soon.
 

Vger

Active Member
Supporting Member
This is speculation based on a post I saw here on the forum, I haven't tried to find the relevant post to link to though. If you are good with the search function here, I think you could find it.

From what I recall the poster indicated that the factory would be focusing on producing more European cars in the near future. When that switch over occurred, the U.S. wait times might push out to 3 to 5 months for a time as the European backlog is filled. I don't know if this is true, but it could be possible to see U.S. wait times start to push out significantly for a period coming up soon.

I doubt that will happen to that great a degree. Remember that Tesla's production has increased by at least 25% (400 to 500/wk) over that last couple months. So even if demand held steady, wait time would go down (not counting the EU bulge). All other indications are that demand is going UP-- buzz is huge, many owners (myself included) report their referred friends recently placing orders, etc.
 

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