Tesla Motors CTO talks future batteries and charging protocols

[vfx]

The key point there is that the Tesla warranty is only a defect warranty (as in a broken battery),....

So a battery is comprised of thousands of cells. If hundreds of them "break" and all you get is a reduction of range, how would you know you have a warranty claim?

 

[JRP3]

Straubel's statement was unambiguous: the Roadster used a chemistry different to laptops.

He said nothing about Roadster cell chemistry. He said "versions of this form factor modified for use in EV's." That could mean external modifications such as PTC devices or fusing. Also worth noting that they speak of a number of different suppliers, further reducing the size of an order from any specific vendor, which also further reduces the likely hood of a vendor making significant internal modifications for an even smaller order than previously speculated.

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So a battery is comprised of thousands of cells. If hundreds of them "break" and all you get is a reduction of range, how would you know you have a warranty claim?

Tesla can easily see if a group of cells in parallel has reduced capacity compared to others in the pack, indicating something abnormal. Parallel group capacity should decrease equally overtime if all cells are degrading together. The only way for this to be "hidden" would be if each group of parallel cells had the same number of cells fail in the same way, or some combinations of cells all reduced overall capacity exactly the same degree in each group. We know Tesla has replaced bad "blades" of cells in some Roadsters.

 

[vfx]

Tesla uses versions of this form factor modified for use in EVs.

Straubel's statement was unambiguous: the Roadster used a chemistry different to laptops. ...

He does not use the word chemistry. The fuses could be the modifications mentioned.

 

[Zzzz...]

I think they were standard chemistry, but according to http://webarchive.teslamotors.com/display_data/TeslaRoadsterBatterySystem.pdf the Roadster cells had PTC protective devices on both anode and cathode. That sounds like they may have been somewhat tailored to the application.

Thank you for posting the link! I quite sure that anyone who will read it carefully will see that at least on mechanical/electronic safety level Tesla Roadster's cells are not off the shelf one... There are even mention of cell's QUOTE: "chemical factors that contribute to their safety". While not definitive proof, overall it is quite clear that Tesla did got custom made 18650 cells, custom made with safety in mind.

Roadster Technology - Battery | Tesla Motors

Awesome find!

QUOTE: "Tesla uses versions of this form factor modified for use in EVs. "

This is definitive proof that Tesla was using custom made cells for Roadster... And could put this discussion to rest finally***.


While I was attacking QUOTE:"naive to think" idea of Tesla using off the shelf cells form chemical level, mechanically/electronically customized cells do show that Tesla was working closely with major li-ion manufacturers for years.

***Claims like this:

This is incorrect. The roadster used Sanyo 2.2ah laptop cells.

In the early Roadster days the battery makers were leery of Tesla's scheme. Sanyo, Panasoninc sold Tesla unmodified batteries.

 

[JRP3]

External changes such as PTC or fuses have nothing to do with cell longevity and are not proof of automotive customized cells. It's quite possible those are standard options that anyone could order. Your whole claim is that Roadster cells had "something" special done to them internally that extended cycle life, something that no one else at the time was using. This is beyond unlikely. The fact is that within a chemistry if you optimize for one parameter the other parameters are lessened. If you could just optimize for specific energy, longevity, C rates, and cost, all at the same time, everyone would. Which of those do you think Tesla was willing to sacrifice?

 

[qwk]

Thank you for posting the link! I quite sure that anyone who will read it carefully will see that at least on mechanical/electronic safety level Tesla Roadster's cells are not off the shelf one... There are even mention of cell's QUOTE: "chemical factors that contribute to their safety". While not definitive proof, overall it is quite clear that Tesla did got custom made 18650 cells, custom made with safety in mind.




Awesome find!

QUOTE: "Tesla uses versions of this form factor modified for use in EVs. "

This is definitive proof that Tesla was using custom made cells for Roadster... And could put this discussion to rest finally***.


While I was attacking QUOTE:"naive to think" idea of Tesla using off the shelf cells form chemical level, mechanically/electronically customized cells do show that Tesla was working closely with major li-ion manufacturers for years.

***Claims like this:

Nowhere in those links does it say that tesla did or didn't use off the shelf 18650's. Tesla has made public statements that they used stock 18650 2.2 ah Sanyo cells many times. This is a known fact. You are arguing against something Tesla publicly stated many times.

 

[stopcrazypp]

Wow, still arguing about the Roadster's battery supply? Roadster's battery was unambiguously supplied by at least Sanyo, and the supply agreement did not specify a contracted amount and also said Tesla can seek other suppliers (see SEC filing):
http://www.sec.gov/Archives/edgar/data/1318605/000119312510017054/dex1027.htm

How likely would Sanyo develop a custom chemistry for a customer who doesn't even have a committed order amount? PTC and fuses definitely could be added (they are typical additions to laptop cells and even if Sanyo doesn't do it directly there's plenty of companies who can add them), but a custom chemistry is a whole other ballgame.

Panasonic with the Model S is different because Tesla and Panasonic are long term partners now (plus the battery order is much larger now), so a custom chemistry is believable.

 

[Zzzz...]

External changes such as PTC or fuses have nothing to do with cell longevity and are not proof of automotive customized cells.

Positive temperature coefficient current limiting device and current interrupt device both mounted internally, within the cell. Sanyo, with a sheer amount of Tesla's order would modify cell line to be able to mount those.

It's quite possible those are standard options that anyone could order.

So now you are changing mindset to admitting possibility of customization by choosing options? No more Tesla buying cell from reseller? This indeed is a progress.

But those are not standard one. You can try to Google off the shelf 18650 cells, sure with so many brands available for sale online you would not have problem to find one? If you could, find one from Sanyo or Panasonic.

Your whole claim is that Roadster cells had "something" special done to them internally that extended cycle life, something that no one else at the time was using.

You have not read my posts??? I never ever claimed that there was anything special done to Roadster cells. All standard practices.
Most likely Tesla was using additives, commercially available ones. To make sure Roadster will start up in freezing temperatures. To limit dendrites formation. Requesting specific particle size range for cathode material - to improve consistency/power density.

This is beyond unlikely.

Once again, there are nothing special. Think of adding those chemical agents as an options. Sanyo or any li-ion manufacturer will have zero problems to do it.
I have said this probably 20 times, here 21st one: this is common practice in the industry.

The fact is that within a chemistry if you optimize for one parameter the other parameters are lessened.

I agree.

If you could just optimize for specific energy, longevity, C rates, and cost, all at the same time, everyone would. Which of those do you think Tesla was willing to sacrifice?

Sure cost, specific energy and C-rate.

Even adding PTC and CID would add to cost and lower cell's specific energy.

Adding antifreeze agent would lower specific energy and C-rate, while increasing cost. Laptop producer would not pay 1/10 of a cent per cell to ensure cell output power at minus 25 Celsius. Tesla might even pay half a cent per cell to ensure Roadster/Model S would start up at minus 35 Celsius (not sure about actual performance in cold weather, but someone here or on TM forum was actually asking about -35 Celsius). And such addition might add 1 gram per cell and -0.2 C-rate. Adding 7 kg to the pack total. Lowering C rate from 5 to 4.8. Or something like that.

Adding additive to lower dendrite formation - again might have a similar effect. Would laptop producer be interested paying extra for such option? As long as cells last 2 or 3 year, answer is no way. Tesla need packs to lasts for 12 years...

Once again, this is all options, available to anyone. Any li-ion manufacturer customer. No voodoo or other magic. Moreover, Sanyo or other cell producer do have scientists on payroll to help their customers to choose best formulation for specific need. Sure Tesla got their own team of chemists too.

But do not get it wrong, the combination of the options that Tesla have chosen are not sold by Sanyo on open market. And it is extremely unlikely that any laptop producer would be interested in cells tailored for Tesla.

Nowhere in those links does it say that tesla did or didn't use off the shelf 18650's. Tesla has made public statements that they used stock 18650 2.2 ah Sanyo cells many times. This is a known fact. You are arguing against something Tesla publicly stated many times.

So you are using PR department statements while I point technical docs?

Again, if you could not get tech docs, could you at least understand two phrases:

QUOTE: "Tesla uses versions of this form factor modified for use in EVs. "
QUOTE: "The cells also incorporate numerous mechanical, thermal, and chemical factors that contribute to their safety in the Tesla Roadster."

Tesla have not used off the shelf cells. Cells were modified for use in EV.
Both Tesla's statements. But unfortunately both docs are too technical for PR people to understand.
When you get this, you will understand that those PR department statements you are referring too are irrelevant to this discussion.

 

[stopcrazypp]

Positive temperature coefficient current limiting device and current interrupt device both mounted internally, within the cell. Sanyo, with a sheer amount of Tesla's order would modify cell line to be able to mount those.
But those are not standard one. You can try to Google off the shelf 18650 cells, sure with so many brands available for sale online you would not have problem to find one? If you could, find one from Sanyo or Panasonic.

CID can't be added later. The PTC can be added afterwards (since it's simply a thermistor), but it's typically built in the cell (much cheaper this way).
Example here (the PTC is simply the thin white ring):
http://mtixtl.com/18650cylindercellcaseandanti-explosivecapwithinsulationo-ring-10-1.aspx
https://batteryworkshop.msfc.nasa.gov/presentations/07_NESC_PTC_Dev_Withstand_Volt_EDarcy.pdf
And PCM/PCBs are of course added outside of the cell.

PTCs are pretty standard in the laptop battery industry, as are protection PCM/PCBs (ones with it are called "protected" cells).

Here's a example from Sanyo:
https://master-instruments.com.au/products/58592/UR18650FM.html
https://master-instruments.com.au/r...Lithium Ion and Lithium Polymer batteries.htm

Here's one from Panasonic:
http://www.ebay.com/itm/1x-Panasoni...rElectronics_Batteries_SM&hash=item53f58f9733

These are bog standard laptop cell options.

So now you are changing mindset to admitting possibility of customization by choosing options? No more Tesla buying cell from reseller? This indeed is a progress.

How is he changing his mindset? Our argument was about whether the Roadster uses laptop cells. PTCs and fuses does not change the cell from being a laptop cell.

You have not read my posts??? I never ever claimed that there was anything special done to Roadster cells. All standard practices.

Would laptop producer be interested paying extra for such option? As long as cells last 2 or 3 year, answer is no way. Tesla need packs to lasts for 12 years...

Once again, this is all options, available to anyone. Any li-ion manufacturer customer. No voodoo or other magic. Moreover, Sanyo or other cell producer do have scientists on payroll to help their customers to choose best formulation for specific need. Sure Tesla got their own team of chemists too.

But do not get it wrong, the combination of the options that Tesla have chosen are not sold by Sanyo on open market. And it is extremely unlikely that any laptop producer would be interested in cells tailored for Tesla.

Lots of contradictions here. You keep saying everything done is "standard" practice. Yet at the same time you argue no laptop manufacturer would opt to use these options (my links above prove otherwise) and that it's not sold on the open market. If no one before Tesla ever used these options, and Tesla came along and requested them, without first committing to a set order (the supply agreement basically says Tesla will only order cells as needed), how likely will Sanyo do something different for them.

So you are using PR department statements while I point technical docs?

Again, if you could not get tech docs, could you at least understand two phrases:

QUOTE: "Tesla uses versions of this form factor modified for use in EVs. "
QUOTE: "The cells also incorporate numerous mechanical, thermal, and chemical factors that contribute to their safety in the Tesla Roadster."

Tesla have not used off the shelf cells. Cells were modified for use in EV.
Both Tesla's statements. But unfortunately both docs are too technical for PR people to understand.
When you get this, you will understand that those PR department statements you are referring too are irrelevant to this discussion.

First, quote is from a marketing piece on Tesla's website; it does not go into any technical detail. Second link is a whitepaper but it also does not go into technical details and no where does it say Tesla uses special cells (all the things mentioned are available in laptop cells).

 

[Zzzz...]

How is he changing his mindset? Our argument was about whether the Roadster uses laptop cells. PTCs and fuses does not change the cell from being a laptop cell.

JRP3 is admitting that Tesla might have choose options offered by Sanyo. Before JRP was claiming that TM could have bought cells from resellers, just ones made for open market.

Lots of contradictions here. You keep saying everything done is "standard" practice. Yet at the same time you argue no laptop manufacturer would opt to use these options (my links above prove otherwise) and that it's not sold on the open market.

You misunderstood me. Offering "options" is a standard practice. But chances that same set of options have been choosen by someone else is miniscule.

If no one before Tesla ever used these options, and Tesla came along and requested them, without first committing to a set order (the supply agreement basically says Tesla will only order cells as needed), how likely will Sanyo do something different for them.

Thank you for linking the agreement!

You absolutely right, Tesla was not committing to a specific number of cells that they had to buy. This is exactly same type of contract Tesla got with Lotus. Tesla was not committing to buy 2000 gliders. But Tesla secured supply of up to 2000 gliders at a given price for a given timeframe.

Same way it works with Sanyo, 7 shipments(I wish they shown number of cells), probably for a total 13.7 millions cells, at a set price.

So supplier is committed to agreement, and had to ship cells up to whatever volume companies agreed to. But Tesla could choose to exit it anytime, if product fail for example. To better explain it lets look at Microsoft Surface. MS did not know how popular would it be. Early on MS had projection that it might sell up to 5 millions Surfaces in 2012 Christmas season alone. Then reality hit, so far MS sold only 1.5 million devices in half a year...

So you see, in MS case they secured supplier volume for up to 5 millions or more batteries a year, for several years. But MS did not committed to buy 5 millions batteries. And it do not looks like they would not need even 3 million batteries for 2012+2013 combined.

It is a common practice, because if supplier would have not been committed to volume at a given price, later on supplier could have increased price betting that customer would not have a time to redesign product/get equivalent from someone else for volumes needed.

But customer is secured. And that is a customer who got leverage, suppliers are the ones who are competing for customers, not other way around.

First, quote is from a marketing piece on Tesla's website; it does not go into any technical detail.

It is quite technical marketing piece then. What qwk was referring is obviously non technical marketing statements. No link was provided, but you could see in agreement you have linked between TM and Sanyo that Tesla could use Sanyo's name in marketing materials however Tesla wants.

And sure Tesla did.

But Sanyo could not mention Tesla in any context except when Tesla give Sanyo written permission. Leverage again.

Second link is a whitepaper but it also does not go into technical details and no where does it say Tesla uses special cells (all the things mentioned are available in laptop cells).

See first quote. It specifically claim that cell design were modified for EV needs. Statement from Tesla. Official. Relatively technical.

The second quote, cells "incorporate numerous mechanical, thermal, and chemical factors" reinforce fist one. If this statement is not a sign of EV modifications of the cell design/chemistry - then what is? Safety is much bigger concern for EVs in comparison to laptops.

But why I had to prove the point?:smile: I mean could you guys come up with anything that could be compared to docs that Doug_G and ItsNotAboutTheMoney(thanx again) linked, that could point toward your point of view?

We had the very similar argument about Panasonic NCR18650A cells in Model S. You, qwk, JRP3, vfx were all claiming off the shelf case. But I was right about EV optimized design for a reason. I'm afraid docs above about Roadster is as best proof publicly available. Unless JB or Musk suddenly come up with similar statements about Roadster cells in a different interview...

PS. Excuse my English.

 

[JRP3]

Laptop cell buyers would certainly care about controlling dendrite formation, remember all the bad press from exploding laptops? Remember the incident on an airplane where cells that were being transported caught fire? Safety is a concern for all laptop cell applications. Also, I'm not sure how you made the jump that Tesla couldn't get cells with certain options from resellers, and I'm not saying Tesla did buy from resellers, just that it was a possibility. Whatever specific options Tesla got in the cells were probably standard elements that anyone could order. Unfortunately I doubt we'll ever get the details from Tesla so we'll never know. If you want to claim you were correct with no solid data to back it up then be my guest.

 

[Zzzz...]

Ok lets get to the bottom of this.

Tesla Motors publicly claims that they used version of cells modified for EV use.
QUOTE: "Tesla uses versions of this form factor modified for use in EVs. " Link.

Bunch of you claims that Tesla was using off the shelf Sanyo batteries.

Why should I or anyone else believe you instead of Tesla Motors?

 

[vfx]

.... We know Tesla has replaced bad "blades" of cells in some Roadsters.

Tesla calls them "sheets".

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...
We had the very similar argument about Panasonic NCR18650A cells in Model S. You, qwk, JRP3, vfx were all claiming off the shelf case. ....

I never said that about the S. The Model S uses batteries optimized for automotive applications. The Roadster chose the best available cells that would work in their car. Nothing you have quoted refutes that.

- - - Updated - - -

...
Tesla Motors publicly claims that they used version of cells modified for EV use.
QUOTE: "Tesla uses versions of this form factor modified for use in EVs. " Link.

Bunch of you claims that Tesla was using off the shelf Sanyo batteries.

Modified does not say an internal chemical change which is your assertion. Maybe they were painted racing red.

 

[qwk]

Ok lets get to the bottom of this.

Tesla Motors publicly claims that they used version of cells modified for EV use.
QUOTE: "Tesla uses versions of this form factor modified for use in EVs. " Link.

Bunch of you claims that Tesla was using off the shelf Sanyo batteries.

Why should I or anyone else believe you instead of Tesla Motors?

There are two videos, one of Musk, one of JB, saying that they used regular laptop cells for the roadster. I have seen both over the years, but looking for them is like looking for a needle in a haystack. Where is Teg when you need him?

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Most likely Tesla was using additives, commercially available ones. To make sure Roadster will start up in freezing temperatures. To limit dendrites formation. Requesting specific particle size range for cathode material - to improve consistency/power density.

Adding antifreeze agent would lower specific energy and C-rate, while increasing cost. Laptop producer would not pay 1/10 of a cent per cell to ensure cell output power at minus 25 Celsius. Tesla might even pay half a cent per cell to ensure Roadster/Model S would start up at minus 35 Celsius (not sure about actual performance in cold weather, but someone here or on TM forum was actually asking about -35 Celsius). And such addition might add 1 gram per cell and -0.2 C-rate. Adding 7 kg to the pack total. Lowering C rate from 5 to 4.8. Or something like that.

Adding additive to lower dendrite formation - again might have a similar effect. Would laptop producer be interested paying extra for such option? As long as cells last 2 or 3 year, answer is no way. Tesla need packs to lasts for 12 years...

You do realize that Tesla uses passages next to every cell using antifreeze to cool/heat the pack? That and the top and bottom 5% of the pack is not used to help longevity(even less than 5% in standard charge mode). That's why the laptop cells in the roadster last quite a bit longer than regular laptop non-cooled and babied cells.

 

[JRP3]

Tesla Motors publicly claims that they used version of cells modified for EV use.
QUOTE: "Tesla uses versions of this form factor modified for use in EVs. " Link.

As has been pointed out that says nothing about internal changes, and in fact may simply reference how Tesla connects and packages the cells in the pack. It's a vague enough statement that proves absolutely nothing at all.

 

[Doug_G]

Hmm... it may be time to send all this to a "Circular battery argument" thread. How about we agree to disagree and move on. Only Tesla knows the answer.