EarlyAdopter
Active Member
Happy to answer all of your questions Art just as soon as Tesla ships me my car! (been stuck "In Production" for two weeks now)
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Range Reduced on Dual Motor Configs?
- Thread starter DJ Frustration
- Start date
Really? I could've sworn I didn't see it yesterday. Oh well. The rest still applies.
ArtInCT
Always Learning
Thanks, and that is somewhat OK that Tesla wants to get the end product "Right". We all do as owners.
And for all of you who are anxiously waiting for your new P85D, we all sympathize and share your moments....
I do look forward to all your reports ... and how you peel back the Onion of the P85D. It will be great fun.
The changes I saw revealed in the P85D and to some extent also in 85D were large... to somewhat trivial but when taken
as a whole are formidable..
1) new Skateboard design for front motor (which is also new in and of itself).
2) probably a new battery layout for feeds to front and rear motor, but possibly not.
3) new brakes with servos vs pump
4) new software, especially to control the dual motors seemlessly
5) new front end geometry for motor and steering
6) new rear doors or actually hinges to the rear doors
7) new seats
8) new TPMS sensors, really a nit but a software change perhaps
9) new soundproofing for front motor
10) new paintshop (i have heard this but am not sure about it)
11) training service technicians in SC's on all the above
and last but not least (I know this all too darned well having worked at Sikorsky Aircraft).....
Production Line Changes to build all the above RIGHT the FIRST TIME....
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breser
AutoPilot Nostradamus
I've been doing some digging trying to find the test procedures that the EPA requires for electric vehicles. I've been doing so because there have been several posts pointing to articles [1][2] about the Leaf saying that the test procedures changed in 2013. I find it really strange that if the test procedures changed for the Leaf in 2013 that we didn't see changes to Tesla's numbers prior to the new P85D window sticker that we've seen.
One long standing idea is that the change from the Normal and Range charging modes on the Tesla to a slider where you could choose a specific value was to avoid the range being decreased like with the Leaf (apparently range averaged between the Normal and Range modes). Nissan resolved this with the 2014 Leaf by simply removing the 80% charge mode entirely [3]. Given that Nissan's solution was to make a UI change it doesn't seem that implausible to believe that Tesla did the same thing. Tesla is in the unique position to update all the cars to new software that effectively makes that UI change retroactively. Nissan appears not to have been in the same position.
The presumptions of many posters pointing to the situation with the Leaf has been that there was a uniform change to the testing procedures in 2013 that is now catching up to Tesla. However, I believe there is another plausible explanation. That the EPA decided that the charge modes were similar to optional driving modes. Someone else linked an article talking about how driving modes were dealt with during testing by the EPA [4]. The article stated that if there was not a predominant mode that the EPA would use the average of the best and worst modes. This sounds very similar to how what was said about the Leaf in the previously mentioned articles (that the 80% and 100% charges were averaged). The article also mentions that this would be handled on a case by case basis and that manufacturers would submit information to try and determine the predominant mode. This leaves things open to the EPA having decided to deal with Tesla in a different fashion than the Leaf, especially since Tesla made a change to their UI allowing a large number of possible charge rates.
So now let's go look at the EPA test procedures and what they say [5]. The final rules for the 2013 model year are published here (PDF). Electric and Plug-In Hybrid Electric Test Procedures are covered on page 24 of that document, where the EPA says they will use the SAE J1634 test procedures (from the October 2002 revision). That is the most current information that the EPA has published on their website as far as the test procedures go. But maybe the EPA just hasn't been very good at updating their regulations on their own website and maybe they really have updated that information. So let's go look in the Code of Federal Regulations. That previous documents references 40 CFR Parts 85, 86 and 600. The Government Printing Office publishes the eCFR which is updated on a daily basis (at this time updated to December 3, 2014). 40 CFR §600.116-12 provides the exact testing procedures for electric and plug-in hybrid vehicles, specifically is mentions SAE J1634 again. It also mentions that SAE J1634 is included by reference and in 40 CFR §600.011, and says that it was revised in October, 2012. That's obviously a newer revision than the October 2002 version mentioned before. So at some point between 2011 and now they have updated to a newer version of the SAE J1634 test procedures.
So what does SAE J1634 say? SAE has a page about the standard on their website. You have to pay to read the whole thing and I'm not willing to pay $70 to fulfill my curiosity in this case. However, you can read a preview of the document and it talks about what has changed, specifically is says that the old standard used a Single Cycle Test and that the new standard allows for Multi Cycle Tests. Meaning in the past you had to charge the car up, and then run it down in a single run to determine the range for each driving cycle. The new test allows them to do multiple driving cycles in a single test while keeping track of the energy usage during the test and then extrapolating this out to the entire useful charge of the battery. This method has been tested to be consistent with the already existing Single Cycle Test and new technologies would have to reprove the faster test procedure stays consistent or use the Single Cycle Test procedure. As far as I can tell that's the only change to the test procedure, though I can't be entirely sure without buying the procedures.
I believe there has been no change to the testing procedures with respect to the state of charge of the battery. However, the EPA may have started considering the battery charge modes as driving modes and then dealt with them on a case by case basis as described above. It's possible that the EPA has now decided that using a 100% charge on the Tesla is inappropriate. There are a couple of reasons why this view may have changed. First the Tesla will revert form range mode after a few days. The language in that one article mentioned reverting to a specific mode on engine start, but perhaps the EPA has determined that range mode is not the predominant mode since it reverts after a few days. Secondly, the EPA may have asked Tesla for data on what the most used charge point is on vehicles. Given that the car reports this information for use by the smart phone app, Tesla should have this information. The EPA may have determined that the predominant mode is not the 100% charge, but some other value.
I'm not sure what the real situation is but I don't think you can just point at the Nissan Leaf articles and say that the standards changed. Once P85D owners take delivery of their vehicles we'll get some real world numbers regarding range. I'd also expect Tesla to make a statement since I'm sure media will pick this up and run with it, especially if the S85 range goes down as well. Until either of those things happen all of this is just very educated speculation.
One long standing idea is that the change from the Normal and Range charging modes on the Tesla to a slider where you could choose a specific value was to avoid the range being decreased like with the Leaf (apparently range averaged between the Normal and Range modes). Nissan resolved this with the 2014 Leaf by simply removing the 80% charge mode entirely [3]. Given that Nissan's solution was to make a UI change it doesn't seem that implausible to believe that Tesla did the same thing. Tesla is in the unique position to update all the cars to new software that effectively makes that UI change retroactively. Nissan appears not to have been in the same position.
The presumptions of many posters pointing to the situation with the Leaf has been that there was a uniform change to the testing procedures in 2013 that is now catching up to Tesla. However, I believe there is another plausible explanation. That the EPA decided that the charge modes were similar to optional driving modes. Someone else linked an article talking about how driving modes were dealt with during testing by the EPA [4]. The article stated that if there was not a predominant mode that the EPA would use the average of the best and worst modes. This sounds very similar to how what was said about the Leaf in the previously mentioned articles (that the 80% and 100% charges were averaged). The article also mentions that this would be handled on a case by case basis and that manufacturers would submit information to try and determine the predominant mode. This leaves things open to the EPA having decided to deal with Tesla in a different fashion than the Leaf, especially since Tesla made a change to their UI allowing a large number of possible charge rates.
So now let's go look at the EPA test procedures and what they say [5]. The final rules for the 2013 model year are published here (PDF). Electric and Plug-In Hybrid Electric Test Procedures are covered on page 24 of that document, where the EPA says they will use the SAE J1634 test procedures (from the October 2002 revision). That is the most current information that the EPA has published on their website as far as the test procedures go. But maybe the EPA just hasn't been very good at updating their regulations on their own website and maybe they really have updated that information. So let's go look in the Code of Federal Regulations. That previous documents references 40 CFR Parts 85, 86 and 600. The Government Printing Office publishes the eCFR which is updated on a daily basis (at this time updated to December 3, 2014). 40 CFR §600.116-12 provides the exact testing procedures for electric and plug-in hybrid vehicles, specifically is mentions SAE J1634 again. It also mentions that SAE J1634 is included by reference and in 40 CFR §600.011, and says that it was revised in October, 2012. That's obviously a newer revision than the October 2002 version mentioned before. So at some point between 2011 and now they have updated to a newer version of the SAE J1634 test procedures.
So what does SAE J1634 say? SAE has a page about the standard on their website. You have to pay to read the whole thing and I'm not willing to pay $70 to fulfill my curiosity in this case. However, you can read a preview of the document and it talks about what has changed, specifically is says that the old standard used a Single Cycle Test and that the new standard allows for Multi Cycle Tests. Meaning in the past you had to charge the car up, and then run it down in a single run to determine the range for each driving cycle. The new test allows them to do multiple driving cycles in a single test while keeping track of the energy usage during the test and then extrapolating this out to the entire useful charge of the battery. This method has been tested to be consistent with the already existing Single Cycle Test and new technologies would have to reprove the faster test procedure stays consistent or use the Single Cycle Test procedure. As far as I can tell that's the only change to the test procedure, though I can't be entirely sure without buying the procedures.
I believe there has been no change to the testing procedures with respect to the state of charge of the battery. However, the EPA may have started considering the battery charge modes as driving modes and then dealt with them on a case by case basis as described above. It's possible that the EPA has now decided that using a 100% charge on the Tesla is inappropriate. There are a couple of reasons why this view may have changed. First the Tesla will revert form range mode after a few days. The language in that one article mentioned reverting to a specific mode on engine start, but perhaps the EPA has determined that range mode is not the predominant mode since it reverts after a few days. Secondly, the EPA may have asked Tesla for data on what the most used charge point is on vehicles. Given that the car reports this information for use by the smart phone app, Tesla should have this information. The EPA may have determined that the predominant mode is not the 100% charge, but some other value.
I'm not sure what the real situation is but I don't think you can just point at the Nissan Leaf articles and say that the standards changed. Once P85D owners take delivery of their vehicles we'll get some real world numbers regarding range. I'd also expect Tesla to make a statement since I'm sure media will pick this up and run with it, especially if the S85 range goes down as well. Until either of those things happen all of this is just very educated speculation.
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breser
AutoPilot Nostradamus
The other possibility is that the insane mode gets much worse mileage and that Tesla is having to report the range as the average between the best and worst modes. That would seem to be more plausable given the state of the standards. The car we have seen a window sticker for was made in November, 2014. If there was a range reduction for the S85 and other vehicles as a test procedure would imply then I would expect that people taking deliveries now would see this range reduction on their stickers.
Let's presume for a bit that the best mode of the P85D still gets 265 rated range. So if you assume the 242 is the average of the 265 and whatever it gets in the insane mode then you can find out the insane mode mileage by solving for x in this equation (x + 265) / 2 = 242. Which comes out to 219.
If that's the case that the P85D does 219 miles in insane mode and still does 265 in whatever the best mode is then this whole thing is a whole lot of fuss over nothing.
That's my educated speculation at this point.
So who's going to drive their P85D in insane mode for 219 miles to find out for me?
Let's presume for a bit that the best mode of the P85D still gets 265 rated range. So if you assume the 242 is the average of the 265 and whatever it gets in the insane mode then you can find out the insane mode mileage by solving for x in this equation (x + 265) / 2 = 242. Which comes out to 219.
If that's the case that the P85D does 219 miles in insane mode and still does 265 in whatever the best mode is then this whole thing is a whole lot of fuss over nothing.
That's my educated speculation at this point.
So who's going to drive their P85D in insane mode for 219 miles to find out for me?
breser
AutoPilot Nostradamus
We don't even know what Insane mode actually does yet. So I can't answer that question.
dennis
Model S Plaid
Here is a summary of the test segments that comprise the EPA mileage test:
As you can see, the max acceleration (and speed and acceleration profiles) are specified by the test. So the acceleration rate would be the same in Normal and Insane modes.
breser
AutoPilot Nostradamus
Here is a summary of the test segments that comprise the EPA mileage test:
As you can see, the max acceleration (and speed and acceleration profiles) are specified by the test. So the acceleration rate would be the same in Normal and Insane modes.
I'm not sure you can rely on that information since that's not the test procedure for electric vehicles. There's even a note to that effect in the screenshot you posted. Though I suspect that the electric vehicle tests are not substantially different in this respect.
The assumption that just because the speed and acceleration rates are the same that insane mode can't change energy usage doesn't really work for me. I'd guess that insane mode probably changes how the car uses the two motors. If it changes the points it switches between motors or runs both for more of the range you may still have increased energy usage even with fixed acceleration rates.
But again without actually knowing what it does we can't really say for sure. I'm inclined to believe the P85D has worse mileage than other vehicles, that is what Jerome said in his email to expect.
Johann Koeber
Happy Owner
Can someone help me with the math?
38 kWh for 100 mi
242 mi range
Battery needs 2.42*38 = 91,96 kWh capacity
We all know it is 85 kWh of which not all are accessible.
Much worse here:
265 mi * 38 kWh/100 mi = 100.7
dennis
Model S Plaid
The P85D is about 275 lbs. heavier. More force is required to move it. So all other things being equal (battery capacity, motor efficiency) it will have less range, as you have stated.
The MPGe number is from the wall. So 100 kwh in from the wall may equal 80 kwh to the battery. That is why the math doesn't work.
It is nearly impossible for a 5% weight increase to account to a 8.5% decrease in range. Weight is a negative but never 1 to 1. More like a 5% increase is a 2% decrease. This should be even more (or less) dramatic for an EV that regens.
We maybe seeing the effect of 21 inch rims and weight. Typically the manufacturer can put in the most common tire for the testing. They may have lumped S85 and P85. But now EPA is saying P85D needs to test with 21s
And then there is the slider question.
The P85D is a new model and may have been hit with new testing rules or just a different interpretation of old rules. The 85D should also have to be retested since AWD vehicles historically have a hit to mileage.
It is nearly impossible for a 5% weight increase to account to a 8.5% decrease in range. Weight is a negative but never 1 to 1. More like a 5% increase is a 2% decrease. This should be even more (or less) dramatic for an EV that regens.
We maybe seeing the effect of 21 inch rims and weight. Typically the manufacturer can put in the most common tire for the testing. They may have lumped S85 and P85. But now EPA is saying P85D needs to test with 21s
And then there is the slider question.
The P85D is a new model and may have been hit with new testing rules or just a different interpretation of old rules. The 85D should also have to be retested since AWD vehicles historically have a hit to mileage.
MartinAustin
Active Member
Just throwing this in, not responding to any particular post, but it looks like there is more and more reason for the EPA to test at 80mph -
Montana legislators pushing for 85 mph speed limit - Autoblog
Montana legislators pushing for 85 mph speed limit - Autoblog
Or at least for the range calculator on the Tesla web site to go beyond 70 mph!
- - - Updated - - -
The fine print on these EPA stickers says "when fully charged vehicle can travel about..." So I it's even more confusing than I thought, because the new EPA rules calculates range as the average of 100% charge and 80% charge. Did they change the methodology without changing the wording on the sticker?
Can someone help me with the math?
38 kWh for 100 mi
242 mi range
Battery needs 2.42*38 = 91,96 kWh capacity
We all know it is 85 kWh of which not all are accessible.
Much worse here:
265 mi * 38 kWh/100 mi = 100.7
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AMPUP
Member
Isn't every 4 wheel drive vehicle less efficient than 2? There are two drives requiring power, no matter if the software balances this somehow, I find it hard to believe that it's not going to consume more power and thus reduce overall range.
An electric motor offers nearly zero resistance when spinning. So 2 motors don't really hurt compared to one. When cruising, you might use 20 hp. 2 motors producing 10 hp each uses nearly identical energy as 20 from a single motor. The extra motor requires a tiny amount of extra energy - so small as to be zero in any calculation.
Now - extra weight is worth something but 2% comes to mind (far more in city, close to zero in highway). Then you have the improved efficiency by gearing the 2 motors differently so one is optimal at 30 mph and one is optimal at 60 mph. This is perhaps worth 5% in overall efficiency.
So net is +3% give or take - with up to 5% in highway and 1% in city. Just rough numbers. Remember the new EPA sticker probably has 21 inch rims instead of 19 with the efficiency numbers.
So it isn't just software, it is optimizing 2 systems for 2 different speeds. This trumps any loses in efficiency.
An ICE system is a totally different beast as it just adds weight and extra resistance with no improvements to counter it.
The whole concept of 2 motors is like having a 2 speed transmission instead of one. In an ICE world, that would represent 20% improved efficiency (if not more).
Now - extra weight is worth something but 2% comes to mind (far more in city, close to zero in highway). Then you have the improved efficiency by gearing the 2 motors differently so one is optimal at 30 mph and one is optimal at 60 mph. This is perhaps worth 5% in overall efficiency.
So net is +3% give or take - with up to 5% in highway and 1% in city. Just rough numbers. Remember the new EPA sticker probably has 21 inch rims instead of 19 with the efficiency numbers.
So it isn't just software, it is optimizing 2 systems for 2 different speeds. This trumps any loses in efficiency.
An ICE system is a totally different beast as it just adds weight and extra resistance with no improvements to counter it.
The whole concept of 2 motors is like having a 2 speed transmission instead of one. In an ICE world, that would represent 20% improved efficiency (if not more).
ArtInCT
Always Learning
No matter what you do to alter the acceleration rate, the overall weight of a vehicle and its total payload is
very important to MPG or MPGe, acceleration and stopping distance. I do believe that I read that the P85D may be a couple of hundred pounds
heavier than the P85+, mostly due to the second engine and differential and some other odd bits like the seats.
Of note is the EV Trip Planner software wants to know the added payload of the car (total passenger weight and luggage, etc)
in order to do its calculations as "accurate" as possible.
Last time I looked the Tesla model S spec sheet did not really differentiate the various model S variants well at all, perhaps
that will be updated soon. Well I just check the Tesla Motors Design Studio and the online spec sheet is indeed still
out of date. It does not mention the dual motors in the Powertrain sub-section.
very important to MPG or MPGe, acceleration and stopping distance. I do believe that I read that the P85D may be a couple of hundred pounds
heavier than the P85+, mostly due to the second engine and differential and some other odd bits like the seats.
Of note is the EV Trip Planner software wants to know the added payload of the car (total passenger weight and luggage, etc)
in order to do its calculations as "accurate" as possible.
Last time I looked the Tesla model S spec sheet did not really differentiate the various model S variants well at all, perhaps
that will be updated soon. Well I just check the Tesla Motors Design Studio and the online spec sheet is indeed still
out of date. It does not mention the dual motors in the Powertrain sub-section.
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dennis
Model S Plaid
Can you please cite a reference that states that range is now calculated as the average of 100% and 80% charges? I don't remember seeing any such citation, including @breser's thorough search for the definition of the current test procedures.
Can someone help me with the math?
38 kWh for 100 mi
242 mi range
Battery needs 2.42*38 = 91,96 kWh capacity
We all know it is 85 kWh of which not all are accessible.
Much worse here:
265 mi * 38 kWh/100 mi = 100.7
Those numbers are measured from the wall, and therefore include charging losses.
The fact that the totals are so different even though the efficiency numbers are the same is a big clue to what is going on here - quite clearly the new rating is based on having less energy on the battery pack - which since the pack is the same size must be a product of the rules about 'normal' and 'range' charging.
Walter
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