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

[AWDtsla]

I just did an example in EV Trip Planner, setting the parameters to 85, 19"; 1.0, 72, 72, and 200 lbs in the cabin for a trip from Mobile, AL to New Orleans, LA. Then I changed the load to 650 lbs or 450 lbs more. Both gave an identical need of 167 rated miles to cover 145.4 miles at an average speed of 68 mph, with most miles covered at 72 mph. Looking closer, the 200 lb run needed 50.0 kWh and the 650 lb run needed 50.1 kWh or 0.2% increase in energy needed for a weight difference of 450 lb, about 7.5%.

Weight calculation is broken in evtripplanner. Add 5000lbs if you want to.

 

[SteveG3]

As I'm not the one trying to make the assertion that dropping 400 lbs *would* improve range by 12 miles, I'm not going to spend any resources trying to prove nor disprove it. But, there is a simple way for anyone with an S to test this. Get in your car, drive somewhere by yourself. Then drive the same trip with 3 more people in the car. I guarantee that you're not going to end up 12 miles shorter on range. I personally have driven from NJ->FL->NC->NJ->NC several times both by myself and with a full car of adults (easily 500 lbs of people and luggage plus myself). There is no significant change in range... maybe a mile or two at most.

that being the case, please retract your assertion that,

"We have more than enough info to prove that dropping 400 lbs along with 4 kWh is going to result in a *decrease* in range, not an increase. This scenario you describe just is not plausible"

 

[wk057]

FlasherZ reports seasonality in his range numbers. I don't see how this is possible with a static Wh/mi. What is this static value?

Ah, ok. So the pack must be under predicting available kWh due to colder temps.

Yeah, most likely. There is in fact more energy available at higher temperatures. I have also cycle tested the Tesla cells as high as 60C. There is some additional capacity possible, something like 1% from full to empty, but mainly it just tends to lower IR a little making faster charging and discharging possible.

- - - Updated - - -

that being the case, please retract your assertion that,

"We have more than enough info to prove that dropping 400 lbs along with 4 kWh is going to result in a *decrease* in range, not an increase. This scenario you describe just is not plausible"

I retract nothing. I've owned three Model S, and my assertion matches my real world experience. Removing 4 kWh is going to decrease range, even if you remove some weight along with it. Simple as that.

 

[kennybobby]

..., and 2) again, if that's the case, how do you explain that range has not improved with weight of the vehicle dropping ~7.5% as of 8/2014 with Tesla continuing to work at dropping weight since then?

The energy required to travel for one hour at 60 mph in a 5000 lb tesla versus a 4500 lb (10% weight reduction) is only reduced by 0.6 kWh. Four hours is a 2.4 kWh reduction in energy for the lesser weight. The weight is a linear effect and only applies to the rolling resistance force component of the load, aerodynamic drag is nonlinear and is a much bigger factor than weight above about 50 mph.

 

[JRP3]

Weight changes of a few hundred pounds will have basically zero effect on range outside of stop and go city driving, and probably not much even then. The whole idea that Tesla decreased the capacity of the cells they used in the 85 car, (but apparently not in the 60 car), is not supported by any real world data.

 

[SteveG3]

But here's the main thing. Let's for a second say that somehow you're right and they've been slowly decreasing the battery's range. How exactly does that excuse them from advertising the wrong spec? Seems like they should be all over that. "We made the car more efficient, so a smaller battery gets the same range! We're awesome!" ... but they're not. So even if you're correct, which I'm fairly certain is not the case, then they're still misrepresenting the pack size today even if they weren't at launch.

once more,

"as to why Tesla would do this, isn't it understandable when your product is known to the consumer as either a Model S P85, 85, 60, 85D, 70D, etc., and you continued to offer the exact same range and performance, you would not change the name of a consumer product from those to something like,

February 2013- June 2013: The Model S 84.2 or 59.4

July 2013-December 2013: The Model S 83.3 or 58.8

January 2014- May 2014: The Model S 82.6 or 58.3

June 2014- : The Model S 81.8 or 57.8"



we are talking about a consumer product. we are also talking about a company and their products which are subject to intense media scrutiny, much of it indifferent to the facts (see Tesla fire hazard, Elon Musk carnival barker/welfare leech, Model S 4th or 5th car for the wealthy...).

 

[ohmman]

as to why Tesla would do this, isn't it understandable when your product is known to the consumer as either a Model S P85, 85, 60, 85D, 70D, etc., and you continued to offer the exact same range and performance, you would not change the name of a consumer product from those to something like...

I'm potentially not understanding your hypothesis, but is it that they slimmed the pack down as they shaved weight from the vehicle, in order to maintain the same range? I can't imagine the packs changed this much - if they were getting better range due to weight shaving, I would think they'd just publish better range on the newer vehicles.

 

[wk057]

once more

Posting the same thing over and over (third time now I believe) doesn't make it any more valid.

Tesla's 85 kWh rating needs an asterisk (up to 81 kWh, with up to ~77 kWh usable) - Page 15

Tesla's 85 kWh rating needs an asterisk (up to 81 kWh, with up to ~77 kWh usable) - Page 14

Tesla's 85 kWh rating needs an asterisk (up to 81 kWh, with up to ~77 kWh usable) - Page 10

 

[Grendal]

I appreciate the effort to get very specific with data. For all practical purposes I don't see any problem with what Tesla is doing or has done. If you break any product down to the fine details you will likely find that it falls short of the advertising. All advertising is a spin to highlight a product in its best light. As an American I am advertised at hundreds of times a day. You can and should take all advertising with a grain of salt. Is Tesla better than all the rest? Not really. They are maybe a little better at some things and worse at others. Is this useful data? Sure. For those that care about such things. Does it really change the car in some way? Not really. In general, we all have a decent idea of what the car can and can't do at this point. For who and what they are, IMO, Tesla is doing a pretty good job.

A McDonald's cheeseburger is not as healthy as they portray it.
A Ford F150 truck will probably not drive up 70% incline like they show in the ads.
Asking your doctor about a drug will probably not cure you of your illness.
An ad for a cell phone will probably not point out the fact the phone is radiating energy right next to your body.

 

[SteveG3]

Weight changes of a few hundred pounds will have basically zero effect on range outside of stop and go city driving, and probably not much even then. The whole idea that Tesla decreased the capacity of the cells they used in the 85 car, (but apparently not in the 60 car), is not supported by any real world data.

I appreciate your sharing your informed opinion JRP3.

let's remember, like all vehicles, what consumers see is the epa rating.

the 5 cycles of the epa tests have the following amount of stops in each cycle:

city: 23
highway: 0
high speed: 4
AC: 5
cold temp: 23

(average of 11 stops per cycle)

note (from the website): EPA has established testing criteria for electric vehicles and plug-in hybrids that are slightly different than those for conventional vehicles.

link to source of information above

Detailed Test Information

- - - Updated - - -

Posting the same thing over and over (third time now I believe) doesn't make it any more valid.

Tesla's 85 kWh rating needs an asterisk (up to 81 kWh, with up to ~77 kWh usable) - Page 15

Tesla's 85 kWh rating needs an asterisk (up to 81 kWh, with up to ~77 kWh usable) - Page 14

Tesla's 85 kWh rating needs an asterisk (up to 81 kWh, with up to ~77 kWh usable) - Page 10

wk, we don't have to agree, but let's at least have a fair discussion.

you again raised the question of why would they not change the labeling from 85 kWh.

I gave you my answer to this. yes, I had given that answer 2 times before, but, you know what 1) you asked the question more than twice before, 2) you never once replied to my answer. it's worth exploring this question, but let's not getting into trying to undermine other people's points by the use of spin.

 

[stopcrazypp]

I will throw out my theory for what happened with the 60kWh vs the 85kWh pack. First of all, my theory on the 85kWh vs ~81kWh measured can be largely chalked up to name plate rating of a new cell (nominal voltage * nominal Ah * 7104) vs "actual capacity" of cells with some wear. This however does not have much bearing as below.

To refresh people's memory, the Model S was released with the 85kWh pack first. The first delivery happened in June 2012. First delivery of 60kWh happened in late January 2013. The 40kWh was a software limited 60kWh pack (and was discontinued April 2013).

Probably what happened was that originally they planned to make three different packs (either with different cells, or with full modules removed), but later decided not to (including cancelling 40kWh pack). So for 60kWh they just took two modules and some cells out of each and kept it as "60kWh". The limitation to remove more cells would be driven by supercharger rate and also degradation rates to maintain the 8 year/125k mile warranty. So I can see why they might make a 64kWh "60kWh" pack outside of pure marketing considerations.

The other theory was that they already designed the 64kWh pack and then decided to call it 60kWh instead of 64 or 65 kWh, but given what happened with the 40kWh (which shows Tesla did not design all the packs in the start), I think my theory makes more sense.

Disclaimer: I did not analyze the math on the "64kWh" claim so I am just using what is was reported.

 

[SteveG3]

I'm potentially not understanding your hypothesis, but is it that they slimmed the pack down as they shaved weight from the vehicle, in order to maintain the same range? I can't imagine the packs changed this much - if they were getting better range due to weight shaving, I would think they'd just publish better range on the newer vehicles.

they could have gone one of two ways... publishing slightly better range several times or saving costs little by little by hitting the same range with slightly falling pack sizes over the past 3.5 years. fwiw, my understanding is they have never bothered to increase the official EPA rating of the 90D to date (though they do include information that the vehicle should get about 6% more range).

 

[JRP3]

I appreciate your sharing your informed opinion JRP3.

let's remember, like all vehicles, what consumers see is the epa rating.

the 5 cycles of the epa tests have the following amount of stops in each cycle:

city: 23
highway: 0
high speed: 4
AC: 5
cold temp: 23

(average of 11 stops per cycle)

Right, but remember because of regen weight differences from stop and go are minimized.
The main problem is the idea that instead of using increased energy density of the cells to increase the kWh of the car while keeping weight the same you are implying they kept range the same while reducing the weight and capacity of the pack. If that were true it would have been a huge marketing blunder, since range is a key criteria for selling EV's. Also, range is most important during long distance steady state driving, and in your scenario the reduced kWh would result in reduced range, since the weight reduction would have no effect.

 

[tezzla]

Great job wk057, it's funny that a lot of the people that denied the 691 thing are denying this also. Facts are facts people! I can (pretty much) guarantee that wk057 would have made this same post if he found that the 85kWh pack was really a 89kWh pack. I'm sure he didn't do this to start a forum war; he's just reporting the facts. (now, back to the popcorn)

 

[SteveG3]

Right, but remember because of regen weight differences from stop and go are minimized.
The main problem is the idea that instead of using increased energy density of the cells to increase the kWh of the car while keeping weight the same you are implying they kept range the same while reducing the weight and capacity of the pack. If that were true it would have been a huge marketing blunder, since range is a key criteria for selling EV's. Also, range is most important during long distance steady state driving, and in your scenario the reduced kWh would result in reduced range, since the weight reduction would have no effect.

I'm not sure that's a marketing mistake. if they saved $1,000 per vehicle by dropping about 4 kWh that's about a one point increase in their gross margins (something Wall Street is intensely focused on), while raising range a few miles every 6-9 months could actually make consumers more likely to hold off on buying a Model S. we could debate whether which would be better (raise the range or raise Tesla's margins), but I don't think it's anywhere close to being an obvious mistake that makes the idea they would do it implausible.

I agree with you about range being most important as a vehicle user in highway driving... but would you not agree that the EPA highway rating is the most useful number regarding range in terms of consumers buying the car? I would agree that if this is the case, it would imply Tesla making a decision based more on what would sell cars/improve margins rather than what would give better results for the consumer once they've bought the car. but, let's back up, in 10 minutes, without having the chemistry background to even consider any potential holes in wk057's methodology (beyond the fact that this is the reporting of one person using their own equipment on cells from a couple of battery packs), in 10 minutes at 3AM last night, I saw alternative explanations to wk057's explanations.

again... I think it's good wk057 looked into this. I think it's good he shared his findings here. I'm just saying, let's take a step back and examine how much information we have and what kind of conclusions we can or cannot conclude from this (especially in a world where once the narrative is out, good luck getting the media to put it in perspective once perspective is available... cases in point: the vehicle fires, the LA times Tesla gagillions of dollars in government dependency narratives). don't conclude my hypothesis is correct, don't conclude wk's is... let's examine what we know, figure out the possible scenarios, and where to go from here.

- - - Updated - - -

I retract nothing. I've owned three Model S, and my assertion matches my real world experience. Removing 4 kWh is going to decrease range, even if you remove some weight along with it. Simple as that.

are you saying removing 4 kWh (this all assumes your analysis is correct) and 400 pounds of weight will reduce EPA range given these facts about the EPA testing cycle,

the 5 cycles of the epa tests have the following amount of stops in each cycle:

city: 23
highway: 0
high speed: 4
AC: 5
cold temp: 23

(average of 11 stops per cycle)

note (from the website): EPA has established testing criteria for electric vehicles and plug-in hybrids that are slightly different than those for conventional vehicles.

link to source of information above

Detailed Test Information

 

[OddB]

Thanks for a very interesting breakdown of "battery internals" wk057! It makes it easier to understand how the battery and range calculations works.

I did a 0-100% charge at a supercharger and recorded the V and A during the charge. (The battery had been driven ~20 k km at that time)
At exactly 0 km range I got 348V and 333A when I started charging. That should equal 3.63V/4.50A on the cell level.
I reached 100% (after 75 min of charging) at 403V and 44A, ( cell level 4.20V and 0.59 A)
It kept charging for 43 minutes, still at 403V until it reached 2A.
When I started driving the range started to decrease straight away, (some can drive several miles before the range change)
I drove until I reached 0% in one go.
I started with a range of 381 typical km and spent 72.4 kWh on the trip. For my 2014 S85 it is agreed by several that Typical = 189Wh/km, and it seems to match my observations on this trip.
I drove 330 km in 3.5 h with an average consumtion of 219 Wh/km 20 kW average drain..or ~3W pr cell

So...
Where did the ~4kWh that I put into the battery after I reached 100% go ?
What is the cut of voltage ? (as I started charging at 348V / 3,63V)
Since the voltage topped off at 403V (4.20 V) the accuracy of the numbers at the screen should be reasonably good ?

72.4 is 6% less than 77, so my degredation is at least less than that.. probably a bit better since the power output wasnt limited to more than ~150 kW, and I could probably have gotten 2-3 kWh more out of it before shutdown..
When I change to Range Mode during a trip I get 2-3 km more range, the green line on the "Trip"-screen also makes a jump. Is it possible that the cut of voltage is variable ? That is my only explanation for the changes in range over different SW versions... I have calculated 189 Wh/km as Typical since day one...

 

[Cottonwood]

Further, data gathered from my hacking efforts revealed that the the anti-brick buffer on the 85 pack is a static 4.00kWh (NO! THIS IS NOT USABLE CAPACITY BELOW 0 MILES). So that comes out to about ~77 kWh usable, max, on a brand new Model S with an "85" pack. Hmm... oddly matches pretty much everything we've ever seen. Applying to the "60" pack gives us about 57 kWh usable, although I believe the anti-brick buffer is slightly different on the 60 pack (unconfirmed). The car's BMS also reports the usable capacity as around 76.5 kWh with a 4 kWh buffer on my own car. See my CAN deciphering document for my CAN deciphering document which includes how to decode this data. The fact that the car reports these values that match perfectly (within 1%) of my cell testing means that Tesla is well aware that these are not actually 85 kWh packs.

Here is another check supporting at least one of wk057 data points.

When my Sig P85 was new, I worked very hard to find out what Wh/mi would equal the rated mile in the display. After many drives that came out to 290 Wh/rated mile.

If you use wk057's number of 77 kWh usable in a pack and divid that by the EPA range of the original P85, that comes out to 290.6 Wh/rated mile. My 290 Wh/rated mile and wk057's 77 kWh/265 rated miles = 290.6 Wh/rated mile in a new pack are remarkably consistent numbers.

 

[MartinScorpio]

Dear wk57, did you test your cells under controlled temperature conditions?

 

[SteveG3]

Here is another check supporting at least one of wk057 data points.

When my Sig P85 was new, I worked very hard to find out what Wh/mi would equal the rated mile in the display. After many drives that came out to 290 Wh/rated mile.

If you use wk057's number of 77 kWh usable in a pack and divid that by the EPA range of the original P85, that comes out to 290.6 Wh/rated mile. My 290 Wh/rated mile and wk057's 77 kWh/265 rated miles = 290.6 Wh/rated mile in a new pack are remarkably consistent numbers.

Cottonwood, my alternative hypothesis is completely consistent with this as there is no difference in what wk057 and I assume about the usable portion of the pack. once more, there are probably other alternative explanations as well... I only spent 10 minutes at 3AM last night coming up with the one I proposed, and I did this without reviewing WK's methodology.

 

[wk057]

Great job wk057, it's funny that a lot of the people that denied the 691 thing are denying this also. Facts are facts people! I can (pretty much) guarantee that wk057 would have made this same post if he found that the 85kWh pack was really a 89kWh pack. I'm sure he didn't do this to start a forum war; he's just reporting the facts. (now, back to the popcorn)

Correct. My intention wasn't to start a war here, but I did know that would be the outcome regardless. And I did post that the 60 kWh was in fact more than 60 kWh... most people seem to have glanced over that, though.

Thanks for a very interesting breakdown of "battery internals" wk057! It makes it easier to understand how the battery and range calculations works.

I did a 0-100% charge at a supercharger and recorded the V and A during the charge. (The battery had been driven ~20 k km at that time)
At exactly 0 km range I got 348V and 333A when I started charging. That should equal 3.63V/4.50A on the cell level.
I reached 100% (after 75 min of charging) at 403V and 44A, ( cell level 4.20V and 0.59 A)
It kept charging for 43 minutes, still at 403V until it reached 2A.
When I started driving the range started to decrease straight away, (some can drive several miles before the range change)
I drove until I reached 0% in one go.
I started with a range of 381 typical km and spent 72.4 kWh on the trip. For my 2014 S85 it is agreed by several that Typical = 189Wh/km, and it seems to match my observations on this trip.
I drove 330 km in 3.5 h with an average consumtion of 219 Wh/km 20 kW average drain..or ~3W pr cell

So...
Where did the ~4kWh that I put into the battery after I reached 100% go ?
What is the cut of voltage ? (as I started charging at 348V / 3,63V
Since the voltage topped off at 403V (4.20 V) the accuracy of the numbers at the screen should be reasonably good ?

72.4 is 6% less than 77, so my degredation is at least less than that.. probably a bit better since the power output wasnt limited to more than ~150 kW, and I could probably have gotten 2-3 kWh more out of it before shutdown..
When I change to Range Mode during a trip I get 2-3 km more range, the green line on the "Trip"-screen also makes a jump. Is it possible that the cut of voltage is variable ? That is my only explanation for the changes in range over different SW versions... I have calculated 189 Wh/km as Typical since day one...

Few things here. First, the voltage reported during supercharger can't be relied on for calculating cell voltages. This voltage is reported under charge, and thus is the voltage being output by the supercharger, not the resting voltage of the pack. Further, the car has it's own loads running during supercharging (cooling pumps, A/C compressor, MCU, etc etc) and these things use power, and the percentage of power used is higher as the charge tapers down.

So while you can kind of get an idea from the supercharging data, it's not the right data to be looking at for something like this.