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dennis
Model S Plaid
While it is great that P85D owners might get some of the lost range back through a future software enhancement, that doesn't explain the apparent discrepancy between the numbers that Tesla submitted to the EPA. In 2012, the test results for the S85 showed 89 MPGe and 265 miles of range. In 2014, the P85D results showed 89 MPGe and 242 miles of range. The loss of range with the same level of efficiency can only be explained by there being less kwh available. There are two theories on this:
1) The 2014 test was conducted with the battery charged to 90% because of a change in the EPA testing procedure. It is my contention that if this was the case, Tesla would have told us.
2) The usable portion of the battery has been reduced through software sometime during the past 2 years in order to provide more of a buffer before the car dies completely. This theory is supported by the drop in wh/mi needed to achieve rated range from 308 to 291 sometime last year. If this is the cause of the lower range at the same MPGe, it will be a bit trickier to Tesla to explain, since they never told current owners that they were reducing the usable portion of the battery.
While this is all conjecture, my bet is the answer lies behind door #2.
nwdiver
Well-Known Member
I wouldn't read too much into shifting efficiency #s... unlike an ICE where most of the energy losses are somewhat consistent (thermal inefficiency) most of the energy 'losses' (?uses?) for an EV are highly variable. As we've all noticed speed, HVAC and wind have a MUCH greater effect on energy as a percentage than an ICE since they represent ~90% of the total vs ~30%. Depending on how it's measured the Nissan LEAF has a reported range of 138 - 47 miles.... that's a HUGE amount of variability.
http://www.forbes.com/sites/energysource/2010/06/11/warning-your-mileage-may-vary/
A small change in the test can yield a relatively large change in the result... just changing the rate at which the car is charged and the ambient temperature can effect overall efficiency by nearly 10%.
http://www.teslamotorsclub.com/showthread.php/39104-What-is-the-Most-Efficient-Charging-Amperage
http://www.forbes.com/sites/energysource/2010/06/11/warning-your-mileage-may-vary/
A small change in the test can yield a relatively large change in the result... just changing the rate at which the car is charged and the ambient temperature can effect overall efficiency by nearly 10%.
http://www.teslamotorsclub.com/showthread.php/39104-What-is-the-Most-Efficient-Charging-Amperage
I'm not out to prove anything. I'm really trying to understand the EPA rating. Cars are reportedly using more power. Elon tweeted there will be a fix in the form of a "Normal" mode that will be more efficient. Did they test with an unreleased "Normal" mode to achieve 89MPGe? It does not sound like this addresses the 242 on the Monroney sticker.
The first delivery of a Model S was June 22nd, 2012. We know they can't sell cars without a Monroney sticker. So the EPA test had to have already happened. The EPA values get grandfathered if the car doesn't change substantially. Tesla didn't need to retest until the P85D...
From SAE document J1634 OCT2012 "Battery Electric Vehicle Energy Consumption and Range Test Procedure" (thanks to breser for finding this document):
Full charge is to be established using the manufacturer’s recommended charging procedure and appropriate equipment. If the vehicle is equipped with a charger, that charger shall be used. Otherwise, the vehicle shall be charged using an external charger recommended by the vehicle manufacturer. If multiple charging power levels are available, the vehicle shall be recharged at the power level recommended by the manufacturer. If not specified by the manufacturer, the recharging power level expected to be most widely utilized by end users shall be selected.
Note: October 2012 is when this change was documented, so it had to go into affect after that date.
On Delivery the slider is set to 90%. At least mine was. I'm sure they know what the most common charge setting is. I think it is pretty clear. Road trips are rare. Nightly charging is frequent. The most common setting would not be a trip charge.
We also have corroborating evidence with the behavior of Nissan and the Leaf range change...
Someone else said (on the TeslaMotors forum) they called Tesla and that person was familiar with the issue and said it was a 90% charge. I can't vouch for the validity and can't seem to find the thread. So this is just another unsubstantiated data point...
I'd believe that the EPA let them use 100% charge for testing if... We have the SAE document basically stating that they have to use the most common charging level...
a) Nissan wasn't forced to remove a lower charge rate to NOT have to take a 10% penalty.
b) I could explain away the missing miles.
If the charge was to 90%, I can't explain why Tesla has not communicated this fact. They don't have a great track record of communication in anticipation of issues. Maybe they will...
I've tried to find info on the additional Battery reserve that explains the missing miles without any luck. Most of the info I found was 81.6 KWH of usable battery. This is used with the whm of 308 for rated range. The whm of 278 is ideal range.
If they actually changed the amount of available battery through a software update. I would think there would have been extensive threads about it and I would have been able to find them. The threads I did find had pretty extensive documentation of using this amount of energy.
One interesting piece of data I didn't know is that the dash display shows rated whm with a dashed red line with the rated whm. This would be an interesting number. If it is at 308 we can surmise that some of the battery wasn't used on the test. Either held in reserve or the result of a lower charge. That number should be 337 whm to get 242 miles out of 81.6KWH. Best I could do was this video here.
TESLA MODEL S *P85D* ACCELERATION - YouTube
The P85D can use so much power it is hard to tell if the line is at 308 or 337. There isn't much space between 300 and the 512 WHM average...
There are quite a few theories. At this point I'm still leaning towards the EPA J1634 explanation, with a lot of other changes muddying the waters.
The first delivery of a Model S was June 22nd, 2012. We know they can't sell cars without a Monroney sticker. So the EPA test had to have already happened. The EPA values get grandfathered if the car doesn't change substantially. Tesla didn't need to retest until the P85D...
From SAE document J1634 OCT2012 "Battery Electric Vehicle Energy Consumption and Range Test Procedure" (thanks to breser for finding this document):
Full charge is to be established using the manufacturer’s recommended charging procedure and appropriate equipment. If the vehicle is equipped with a charger, that charger shall be used. Otherwise, the vehicle shall be charged using an external charger recommended by the vehicle manufacturer. If multiple charging power levels are available, the vehicle shall be recharged at the power level recommended by the manufacturer. If not specified by the manufacturer, the recharging power level expected to be most widely utilized by end users shall be selected.
Note: October 2012 is when this change was documented, so it had to go into affect after that date.
On Delivery the slider is set to 90%. At least mine was. I'm sure they know what the most common charge setting is. I think it is pretty clear. Road trips are rare. Nightly charging is frequent. The most common setting would not be a trip charge.
We also have corroborating evidence with the behavior of Nissan and the Leaf range change...
Someone else said (on the TeslaMotors forum) they called Tesla and that person was familiar with the issue and said it was a 90% charge. I can't vouch for the validity and can't seem to find the thread. So this is just another unsubstantiated data point...
I'd believe that the EPA let them use 100% charge for testing if... We have the SAE document basically stating that they have to use the most common charging level...
a) Nissan wasn't forced to remove a lower charge rate to NOT have to take a 10% penalty.
b) I could explain away the missing miles.
If the charge was to 90%, I can't explain why Tesla has not communicated this fact. They don't have a great track record of communication in anticipation of issues. Maybe they will...
I've tried to find info on the additional Battery reserve that explains the missing miles without any luck. Most of the info I found was 81.6 KWH of usable battery. This is used with the whm of 308 for rated range. The whm of 278 is ideal range.
If they actually changed the amount of available battery through a software update. I would think there would have been extensive threads about it and I would have been able to find them. The threads I did find had pretty extensive documentation of using this amount of energy.
One interesting piece of data I didn't know is that the dash display shows rated whm with a dashed red line with the rated whm. This would be an interesting number. If it is at 308 we can surmise that some of the battery wasn't used on the test. Either held in reserve or the result of a lower charge. That number should be 337 whm to get 242 miles out of 81.6KWH. Best I could do was this video here.
TESLA MODEL S *P85D* ACCELERATION - YouTube
The P85D can use so much power it is hard to tell if the line is at 308 or 337. There isn't much space between 300 and the 512 WHM average...
There are quite a few theories. At this point I'm still leaning towards the EPA J1634 explanation, with a lot of other changes muddying the waters.
I'd suggest it's pretty simple:
1) Everyone knows (or should know) that the EPA numbers are just numbers and that real life values can vary immensely. The EPA number has little to do with actual results. The reason many people don't realize this is that most cars don't tell and most people don't keep logbooks.
2) There are penalties for overstating the number.
3) If a large number of people who purchase the car complain that the EPA numbers are too high (not withstanding point 1) then Tesla looks very bad.
4) Most car manufacturers are just looking for an excuse to make EVs look bad so they can continue business as usual. This happened to the Prius and industry pressure caused the EPA to change the fudge factor for hybrids.
I think both theories are possible, but I lean more to #1 (with, as Crasch put it, other changes muddying the water).
dennis, don't get me wrong, there's definitely something to the points you are raising. First, if the EPA number is from a less than 100% charge, it will be a coincidence if it's the same 90% charge as Nissan's testing was done in, not an automatic 10% adjustment to all EVs as implied in an online article. Second, you raise the point that Tesla wants to put things in the best light... why wouldn't they just share that the testing was done at under 100% charge? I agree... they do want to put things in the best light, but the timing of when they feel they can best put out the message is not always immediate. How long were there reports of drive train noises, and frequent drive unit replacements before Tesla spelled out the rather benign details in a fairly comprehensive manner (IIRC that happened in early August on an earnings call with analysts)? In that case, there were even critical articles being written to make a bear case against the company's stock suggesting far more problematic underlying circumstances than reality, in addition to Edmunds publicly documenting multiple drive unit replacements... but Tesla was silent for months. So, similarly, I think Tesla may be waiting for all the moving pieces to be resolved before they put out the details of how the current Model S offerings efficiency, EPA ratings, etc can be reconciled with the 2012 numbers. We now know further work being done is being done on how the motors are used in various circumstances... that certainly is a moving piece in the overall picture of the car's efficiency, and may even change EPA numbers.
Bottom line Dennis... I agree that there have been reports throwing out the testing change idea (testing at a lower charge level) with false assumptions of details and certainty, and it's helpful to point out the misleading nature of those reports. I just don't see taking that to mean that the theory that the testing was done at a lower charge level is off the table.
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breser
AutoPilot Nostradamus
Nope I have no information to prove that the battery reserve has increased other than the anecdotal evidence of what people have posted on the forum. It's just a theory.
The battery charge level bit is in the single-cycle testing section that didn't change in 2012. The multi-cycle testing section simply refers to the single-cycle testing by reference for this information. I don't believe that this charge level piece changed.
I'm sure you're right that the Model S initially was tested under the October 2002 J1634 revision, because that revision didn't exist until October 2012 and it couldn't be used until the CFR was updated which is presumably much later. But I'm also sure that there wasn't any change that changed the numbers. The rationale given for the change is to allow quicker testing of EVs with longer ranges and the 5-cycle test while producing the same numbers. If the charge level part of the standard was changed at this time it's going to start producing different numbers, something that surely would have warranted a comment to that effect in the rationale section.
So I don't think anything has changed with that respect of the standard. Go buy both the 2002 and 2012 versions and see for yourself.
We're talking about laboratory testing under controlled conditions. The test results should come out fairly close unless there are changes to the tests or changes to the vehicle. Some people believe that changes to the tests are the more likely explanation for the unaccounted for range loss.
From what I've heard cars are using more power than even what's on the current window sticker. Which is why I believe the window sticker was tested using software that controls the motor usage differently than in the cars that have been delivered.
When I picked up my car it was on 100% charge. I was not told a recommended charge level. Instead I was told to charge to the level I needed for my usage but that most people charged to 80-90% on a regular basis. On many threads I've seen people report all sorts of numbers as recommendations from Tesla.
Someone said the same thing to me on greencarreports comments section. They said they called the 800 number, got put on hold and that was the answer they were given. I don't put too much belief into this story. I'm sure they're told it but it's important to remember that Tesla employees read things online too. There was even a thread on the official forums titled "New EPA tests explained" that gave the 90% theory. My Owner Advisory 2 days ago was still quoting the 295 number for the 85D and comparing it to the 265 number for the S85. So I think Tesla front end employees are in the dark about this as much as we are.
I've said before that it's possible the EPA has now made them test based on data of what is the actual most used charge level. But...
This is my big hang up. If the tests were at something other than 100% charge I'd expect Tesla to explain that. It'd quickly put to rests the concerns over range.
For what it's worth my S85 had the rated Wh/m around 290. Definitely wasn't 308.
breser
AutoPilot Nostradamus
Good point and that's absolutely true. For what it's worth the MPGe numbers are from the wall and not the battery too.
The 6kW reserve is based purely on anecdotal evidence. Someone said they remembered getting 80 kWh as used charge, I've seen a lot of people saying you can't get more than 74kWh out of the battery now. The actual reserve is hard to discover considering that most people don't want to drive their car until it stops. If you remove charging losses from the .38kW/m then that makes the number go up and allows for the actual reserve to be less.
After looking at the calculations for the range I just can't find a way that the range can be off from the MPGe numbers unless the Usable Battery Energy changed or the State of Charge used in testing changed. It has to be one of these two things.
If it's a matter of State of Charge being different because the EPA told them they couldn't use 100% anymore and had to use data from the existing cars to come up with some number based on real usage (and I pointed this theory out when I posted the original info about the J1634 standard) then I'd think you'd see Tesla explaining that. Also I'd think that the EPA would make them adjust the numbers for the S60/S85 in the same way. But so far that hasn't happened.
Tesla could have decided to make this change themselves and just didn't want to do it to the S60/S85. But that seems really unlikely. I just can't imagine why they'd want their new supposedly more efficient vehicles to look worse.
So that leaves me with the Usable Battery Energy theory. It's the only one that makes sense to me.
Nobody is going to be able to prove either one is correct. Someone at Tesla (or possibly the government) would have to tell us.
dennis
Model S Plaid
breser
AutoPilot Nostradamus
Not sure if that's sarcasm or not but I've said that I thought the vehicle charging to 242 at 100% would settle the matter. But clearly it hasn't for a lot of people. So I've stopped bringing it up.
But yes as far as I've seen there is nothing in the regulations that determine what Tesla has to show in the actual vehicle as estimated range. It doesn't have to be based on the EPA numbers, they can show whatever they want. The regulations only relate to what shows on the window sticker (and I think marketing materials).
dennis
Model S Plaid
Sorry, I missed that you had already made the point about showing 242 Rated miles at 100% charge. I would have expected that to kill the discussion about 242 being the result of a 90% charge level in the EPA test. Maybe others missed it too.
Early on Telsla showed Ideal (300 for an 85 @ 100%) and Projected (based on recent actual usage). Projected got replaced with Rated, which was set to the EPA range (265 @ 100%, at least on a new[ish] battery). So showing the EPA range of 242 @ 100% is consistent with current practice.
Several owners on another thread reported this morning that their Rated range increased by 3-6 miles after installing the latest software update. I wonder if they are now showing 250 Rated @100% if the car has 19" wheels??
MarcG
Active Member
stopcrazypp
Well-Known Member
What they show on the screen doesn't really explain what is on the sticker. Like breser says, they can show whatever they want on the screen and even back then for the "265 miles" rated, it doesn't really match with the EPA number because of the ambiguity of the bottom when it reaches zero (I forgot the exact numbers but the Wh/mi number required to match the 265 miles range is different than what you expect taking it at face value).
The EPA test procedure is to run the car dry regardless of what the display shows (so the test does not stop when it shows "0" but rather when the car can't keep up with the drive cycle anymore).
And the mystery of how a car with the same 89 MPGe and same capacity of battery (presumably) and same charging efficiency can get different range numbers (242 vs 265) is still unanswered. There's only 3 possibilities I can see:
1) EPA procedure limited the percentage of charge during the test
2) Tesla limited the usable capacity of the battery
3) The MPGe numbers on the sticker do NOT correspond to the range number and either one will have to be updated in the future.
What we do know is that there is a pending change that will improve efficiency, and that "normal" mode will return (probably referring to the same change), which might be related to this.
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no problem, I just wanted to be clear I wasn't personally readying pitchforks and torches - having recently been on the more aggressive side of complaining, don't want to get a reputation
anyway seems like this has moved on a bit thanks to Elons tweet which seems to have become the primary comms channel.
breser
AutoPilot Nostradamus
I'm almost certain they can't do this. Range and MPGe are derived from the same test runs. Even if you do multiple test runs you can't pick and choose which ones you like (unless they are disqualified for a variety of reasons) and have to include all the results. For what it's worth Hyundai/Kia just got in trouble for picking and choosing their results.
MarcG
Active Member
I'll be able to answer that very question early tomorrow morning
Alright guys, I charged overnight to 100% before doing the software update and it showed 244 miles of range on my P85D with 19" wheels.
After doing the software update, the range at 100% showed 252 miles.
I'm now at the Corning supercharger on my way to Oregon (drove 172.3 miles at 10mph over the limit and ended up with 2 miles range left!)
I'll be posting all the details of my trip in another thread and update the Google doc with the data, so stay tuned!
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