Tesla's 85 kWh rating needs an asterisk (up to 81 kWh, with up to ~77 kWh usable)

[Kalllagtunet]

I find it interesting that when Auzie makes a point that is accepted across many industries, you respond with this. Most research is able to stand up to peer review.

Why would you feel a need to take a pot shot at Auzie's post?

She is asking for peer review of info from from WK one the most transparent trustworthy members of this whole forum one of the few actually that contribute with facts and data not more just his opinion like the rest of us. I so far have not seen any facts presented from Auzi I have only seeing a consistent stream of post with the intention to tear down and downgrade the little objective facts WK and others have provided here or in the other astrix tread.

I simply ask for the same transparency from her. How important are TSLA in her stock portfolio?

 

[dsm363]

Auzie

How large part is TSLA of your stock portifolio?

And if someone on an Internet forum told you 1% how would you verify this? If you don't trust what they are saying already why would you trust what they told you about their portfolio?

 

[tomas]

New to this thread, so apologize if this has been asked and answered: WK - what was the age/usage history of the cells you tested? I know that my most significant capacity degradation (about 5%) came over first 18 months and has been very stable since. If your testing was done after that initial break-in loss, wouldn't that about foot with 85 as shipped?

 

[apacheguy]

I find it interesting that when Auzie makes a point that is accepted across many industries, you respond with this. Most research is able to stand up to peer review.

Keep in mind that even peer review in scientific journals is not fullproof. A good amount of results out there are not reproducible.

 

[Kalllagtunet]

And if someone on an Internet forum told you 1% how would you verify this? If you don't trust what they are saying already why would you trust what they told you about their portfolio?

Of course way of doing that but thanks for emphasize my point of Auzie and others that do not share anything can discredit the work of WK and others can do this without ever revealing or in the danger of others to reveal the “backdrop” for their position in the subject discussed in these astrix treads.

Let’s not continue this discussion on Auzie. I have made my point and you got it :-D

 

[techmaven]

Seriously, wk057 has access to the BMS read outs. Plus, the data sheet is known to be optimistic, and that's 3.7 volts x 3200 mAh x 7104 cells = 84.1 kWh. A more realistic, testable output would be 3.6 volts x 3150 mAh x 7104 = 80.6 kWh. The fact that he even can get 81 kWh out of a spec sheet of 84 kWh is pretty impressive. Now, the fact that Tesla gives you access to 77-78 kWh of it, or about 96% of the battery and it still holds up is also pretty impressive.

Now, the issue really is, should Tesla have re-assigned the ratings based on realistic outputs, or on maximum, manufacturer ratings? There is likely a set of conditions in Panasonic's lab that can justify the original ratings. I posted the hard drive analogy earlier... you buy a 2 TB drive, that doesn't give you 2 TB of usable disk space. In the end, whatever we bought, we had 77-78 kWh of useable capacity, less if you push it hard or if it was colder. The car seems to match EPA rating of 265 miles pretty well.

 

[Auzie]

Everybody separates their weed differently, but its always better to remove seeds and stems...

As far as your peer review and procedures comment, it is reductio ad absurdum--if nobody can post results and findings without being peer-reviewed first, then nothing will ever be discovered.

Other folks have measured cell capacity and posted on this and other internet forums with exactly the same results within significant figures. The methods and procedures for testing and making voltage and current measurements are well known and commonly established and practiced by those skilled in the art.

Perhaps my point was not clear. I am not disputing validity of publishing any results. I find this forum quite interesting because so many people publish and discuss their measurement results.


I am disputing validity of making statements and claims based on results which were not peer reviewed.


If I were to publish any results and make statements and claims that can adversely affect a single person, I would make sure to find as many people as I can that have knowledge on the subject and I would ask them for a verification.


When it comes to legal statements and claims against manufacturers based on someone's measurements, then the courts usually go a step further and ask for a certification, not just verification.

 

[Auzie]

Doesn't that cut both ways, as most of the claims by Tesla themselves are little more than this.

..............

We are civilised society - now I am making unverified statement.

All manufacturers are subject to periodic audits and certifications by various bodies to be able to legally trade and to be able to make certain claims that buyers of their products have no way of verifying.

If they fail these audits they do not get required certification and they can not trade.

These audits are quite rigorous and guaranteed to pick up anything potentially wrong with Tesla's claims that are relevant to consumers.

 

[Shaggy]

So is this is like the massive issue (resolved via lawsuit) about displays a time back: View-able size, CRT size such that now we have 32" Class TV with 31.5" view-able as required info? People arguing dpi of the display, etc.

If I'm told I have an 85 kwh battery, I should be able to be shown Something x number of cells = 85 kwh. Anything else is an 85 kwh equivalent or 85 kwh class (which are silly). I would accept Tesla telling me the numbers they get from their cell manufacturer and then as stated somewhere WAY back, my issue is with Tesla, Tesla's with their cell manufacturer.

Range is another number that is a different measure. It should be discussed outside of this number.

It seems this could easily be diviaded into two things. Tesla saying what the cells are as reported to them by their Manufacturer at whatever they wish to report it as (ideal, typical, whatever) and Tesla multiplies that by the number of cells and simple math gives a battery rating. Everyone can then debate if they should report that number and a usable number the so called 85/81 kwh. Both numbers are arrived at with simple math and THEN we discuss what is actually going on.

Seriously this far in and the resolution should be that Tesla can say we get 85 kwh from number of cells times... and we're done. We can then move to how come we don't get that. No if Tesla doesn't say anything, it may take an official complaint to get the info about consumers being deceived or something.

Debating methods at this point sounds very premature, the question is raised. He doesn't see how 85 kwh is ever there. We first have to find out how/why Tesla says 85 kwh, until then it's pages and pages of hypothetical. There are several variables you can try to control for, but until you know what the ideal starting point is, it's educated guessing.

 

[flathillll]

your forgetting to account for the 4kwh lead acid battery!

haha jk

this NCA cell only delivers the rated capacity maybe 1-3 times if discharged at 0.1C and the cell is brand spanking new

by the time the cell is installed in a pack and sold it is already a few
months old and has undergone calendar aging and cell matching cycle tests. panasonic also cycles
the cells before they are put on the boat to Tesla. after cycling they are left a full charge for a few weeks to weed out the non Tesla grade cells (very tight self discharge limit). cells with abnormal self discharge are the ones that are most likely to randomly vent fire.

I've seen 10% loss just storing NCA cells for a year. NCA shows rapid decline at first and then levels out (looking at either cycle life or calendar life)

 

[apacheguy]

your forgetting to account for the 4kwh lead acid battery!

haha jk

this NCA cell only delivers the rated capacity maybe 1-3 times if discharged at 0.1C and the cell is brand spanking new

by the time the cell is installed in a pack and sold it is already a few
months old and has undergone calendar aging and cell matching cycle tests. panasonic also cycles
the cells before they are put on the boat to Tesla. after cycling they are left a full charge for a few weeks to weed out the non Tesla grade cells (very tight self discharge limit). cells with abnormal self discharge are the ones that are most likely to randomly vent fire.

I've seen 10% loss just storing NCA cells for a year. NCA shows rapid decline at first and then levels out (looking at either cycle life or calendar life)

Calendar aging for these cells has been shown to be minimal when properly stored (<= 50%). I'd be extremely surprised if Panasonic ships, or stores for a period of one week, their cells at 100% SOC.

 

[flathillll]

Calendar aging for these cells has been shown to be minimal when properly stored (<= 50%). I'd be extremely surprised if Panasonic ships, or stores for a period of one week, their cells at 100% SOC.

the worst thing about nca cells is they rapidly degrade. the best thing about nca cells is the degradation quickly levels out. this applies to both cycling and calendar

again Panasonic performs a short term self discharge check at full voltage at the factory and then Tesla does their own cyclihg test. if capacity looks good Tesla does its own self discharge test but this time it is done NASA style where it is tested for weeks(fully charged then put in temp
controlled room for weeks and then voltage drop measured). This is not the cheapest or easiest way to test cells but it is the best way to screen duds. comparing self discharge is the best predictor we have to screen. any outliers fail QC.

it is the reason why have 20 year old SAFT NCA cells operating perfectly right now in satellites flying outside but those cells are so precisely matched they dont even use a BMS. only mission crit sats skip the BMS. Tesla is using the most agressive
screening procedure seen outside aerospace

 

[jcaspar]

I find this whole thread very amusing.I suspect Tesla calculated their 85KW battery capacity by using the manufactures cell rating, which no one hear seems to know. Maybe this rating was a bit optimistic or under ideal situations (as often most such ratings are given) but I bet it added up to 85KW. The conspiracy theories here border on paranoia. All based on some non certified cell tests on which no one would ever base a battery capacity rating. Even worst case scenario, we are talking a 5% variation. This is not Volkswagen's cheating on emissions by producing up to 35X the measured pollutants to gain subsidies and tax credits from the US government. Tesla has no reason to try to intentionally mislead consumers as no car has a capacity even close to Tesla's. We all got the range we were promised. Lets move along...

 

[JRP3]

Why would we move on from trying to find accurate data?

 

[AWDtsla]

I find this whole thread very amusing.I suspect Tesla calculated their 85KW battery capacity by using the manufactures cell rating, which no one hear seems to know. Maybe this rating was a bit optimistic or under ideal situations (as often most such ratings are given) but I bet it added up to 85KW. The conspiracy theories here border on paranoia. All based on some non certified cell tests on which no one would ever base a battery capacity rating. Even worst case scenario, we are talking a 5% variation. This is not Volkswagen's cheating on emissions by producing up to 35X the measured pollutants to gain subsidies and tax credits from the US government. Tesla has no reason to try to intentionally mislead consumers as no car has a capacity even close to Tesla's. We all got the range we were promised. Lets move along...

"Maybe" but Tesla lost credibility with the HP issue. The rating was clearly BS from the beginning, it just took a long time to wade through the sea of apologists for an official answer.

The damage is already done. My willingness to recommend or talk about Tesla with other people has already been severely limited. I can't give them any honest numbers, from horsepower, to quarter mile times, to supercharge times, to battery size and range.

edit - To the bigger picture, Tesla is failing to cross the hump from early adopters who will put up with any amount of BS just because it's new and the only worthwhile electric car, to mass adoption.

 

[flathillll]

"Maybe" but Tesla lost credibility with the HP issue. The rating was clearly BS from the beginning, it just took a long time to wade through the sea of apologists for an official answer.

The damage is already done. My willingness to recommend or talk about Tesla with other people has already been severely limited. I can't give them any honest numbers, from horsepower, to quarter mile times, to supercharge times, to battery size and range.

edit - To the bigger picture, Tesla is failing to cross the hump from early adopters who will put up with any amount of BS just because it's new and the only worthwhile electric car, to mass adoption.

Tesla never lied. The motor power rating is technically correct on all the cars they have sold and so is the battery rating. They play the same game as everyone else.

Given time all cars will be required to be sold with an actual usable capacity rating but even then some people will never be happy. Should usable capacity be based on a virgin pack or should it be estimated after 8 years or should it be based on....

Until these types of questions are answered Tesla will stick to industry standards (which some may argue are
shady or misleading) but at least are technically correct and have some formal basis

again Tesla has NEVER lied with either the pack capacity or Power specs. Do you really think they are that stupid? to win you have to play the game

 

[AWDtsla]

Tesla never lied. The motor power rating is technically correct on all the cars they have sold and so is the battery rating. They play the same game as everyone else.

Given time all cars will be required to be sold with an actual usable capacity rating but even then some people will never be happy. Should usable capacity be based on a virgin pack or should it be estimated after 8 years or should it be based on....

Until these types of questions are answered Tesla will stick to industry standards (which some may argue are
shady or misleading) but at least are technically correct and have some formal basis

Tesla already backed down on the HP issue, but the apologists keep swimming upriver?

Hmmmph.

Do you really think they are that stupid?

2 years ago I would have said no. Today, I will say yes.

to win you have to play the game

There is no game. They would have sold the same amount of cars with the correct HP and correct capacity. They've only lost credibility.

 

[flathillll]

Tesla already backed down on the HP issue, but the apologists keep swimming upriver?

Hmmmph.



2 years ago I would have said no. Today, I will say yes.

There is no game. They would have sold the same amount of cars with the correct HP and correct capacity. They've only lost credibility.

that is only true because they have no competitors now. but be assured ALL the major automakes have Tesla killers in the stable and Tesla has no idea when they will be released. one thing you can be sure of is they will play every trick in the game book when advertising their cars. the will use the same motor regulations and the same method to calculate pack capacity. they would be stupid otherwise.

just because you dont like how the game is played doesnt change anything. the only reason new laws will be mandated to state usable capcity will be when a competitor with better cells will lobby for it to make their car look better "on paper"

making new laws to benefit your corp is another aspect of the game

the wise words of a g rapper:

f the game; player for life

 

[Ben W]

This gets even more confusing because RAM and Flash Drives are sold in the binary equivalents while hard disks are sold in decimal values.

There's been an odd exception to this rule recently. After 64GB and 128GB (binary) flash drives, the next iteration is 192GB (binary) drives, and some marketing whiz realized that 192GB (binary) ~= 201GB (decimal). So this new generation of flash drives is universally being advertised as "200GB", rather than 192GB. Go figure.

To the nerds among us (I work at Google), the standard naming convention is to label the binary versions as "MiB", "GiB", "TiB", etc. (Mebibyte, Gibibyte, Tebibyte), relative to the decimal MB, GB, TB (Megabyte, Gigabyte, Terabyte). It takes some getting used to, but as you get into Petabyte and Exabyte territory they really start diverging, so it's useful for clarity. (Beyond exabyte, the next two steps are zettabyte and yottabyte, and the one after that is either hellabyte or brontobyte, depending who you ask.)

My reaction to this whole thread... It's universal for any marketer to ratchet up their advertised specs to the highest degree they can rationalize, because if they don't, the next guy will. So airfares are advertised with all the taxes and fees removed, food "serving" sizes are unrealistically tiny, performance of computer chips (in gigaflops/teraflops) is not practically achievable if you're trying to do anything useful, and you can't really drive a "200-watt" audio receiver at 200 watts, without destroying your speakers. (Unless you're playing a pure sine wave test tone in a vacuum. Yes, yes, I know.)

So since the Tesla battery cells can theoretically (under laboratory conditions) charge to 4.35 volts, and when you multiply that literal figure out you get 85kWh, Tesla can rationalize calling the battery pack "85kWh." The same logic goes for the "691HP", and also probably to all the other battery capacity figures from the other EV manufacturers. My guess is that the rationalizable limit for the "60kWh" battery pack might have been closer to 64kWh; not quite enough to be able to justify "65kWh", and then given that round numbers sound a lot nicer, they settled for "60kWh". If humans counted in Base 9, Tesla would doubtless have rounded these marketing figures to 63 and 81 ("70" and "100" in base 9, respectively), and then we would be arguing here about the 63 pack instead of the 81 pack.

To ordinary drivers, the EPA mileage figure is a lot more meaningful than kWh in practice, and I'm also glad their test allows driving the car past the "zero" point; it allows Tesla to set the zero point more conservatively without being penalized, which is better for drivers. And with 36k miles on my 2012 P85, my battery capacity has diminished perhaps 8% since new; I can still range-charge to about 242 rated miles on a good day. (~220 miles on a standard charge.) Lifetime efficiency is about 351Wh/mi, about 12% worse than the EPA rating. (21" rims don't help.) To me, all of this is completely and totally expected.

Just my two cents. Carry on

 

[schonelucht]

It is unsubstantiated to make claims about Tesla battery pack capacity or anything else just by doing few measurements, but it certainly draws traffic to this thread.

The burden of proof is on Tesla for making the original statement that their pack is 85kWh. They never did, so wk057 is fact checking Tesla Tesla's claims and so far they are not holding up. You may also have missed the other thread (parts on the bench) were a substantial part of wk057s research has been independently duplicated and validated (notably the cell voltages at different charge states). So if you want to be pedantic about it all, the right statement to make is that there is currently no evidence that the packs sold as 85kWh actually have said capacity.