SageBrush
REJECT Fascism
Those numbers are for usable energy. Presuming a minimal 2 kWh reserve to prevent bricking puts the pack at ~ 80 kWh
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[Spoiler Alert + Mild Speculation] Tesla has created a monster!
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- Model 3
stopcrazypp
Well-Known Member
Well he actually said this.
"The shorter wheelbase only allows for a 75 kWh pack in Model 3 at current cell/module energy densities".
Elon Musk on Twitter
However, what does he mean by "75 kWh pack" still gives a lot of leeway. 75kWh usable, 75kWh nominal (conventional), 75kWh nominal (Tesla marketing, where it can have significantly more or less than this amount as subject in other threads).
He could have simply meant a pack that if they used the old scheme (instead of calling it "long range") would be advertised as "75kWh".
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The current believe based on the EPA data is that it's about 78 usable and over 80 total. I was worried about the 3 range compared to my current Model S when Elon made the original 75kWh statement, but now it looks like it might actually have more battery capacity than my S85. However, for some reason my reaction is pure delight, not some sort of strange anger. If anything, I think it was kind of slimy to have called the original pack an 85kWh. I'd much prefer they talk about usable capacity and round down.
Is that 87% is the product of battery round trip efficiency and onboard charger efficiency?
SageBrush
REJECT Fascism
Wall to battery
Background:
Agencies like the EPA fill up the car battery and then drive the car until it cannot continue whatever test cycle it is on. The car is then charged to 100% of manufacturer allowed by an L2 EVSE. This energy to fill the battery to full is the only well metered quantity.
The battery charging efficiency is derived. The EPA has reported in the past a presumed efficiency that is good enough for government work but not car specific. Car companies can report actual energy consumed out of the battery (using on-board coulomb counters, etc) while performing the range test although I don't know if this is required for EPA certification. Tesla reported ~ 78 kWh for the Model 3 LR. We came up with 12.5% charging efficiency here by dividing the Tesla supplied 78 kWh (in the car) into the EPA measured 89 kWh (from the wall.) Numbers rounded due to my poor memory.
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Yeah, agreed.
I was illustrating that the total could be "closer to 80" as @apacheguy stated and the usable at about 75 as Elon had referenced.
It's looks like this is spreading through the normal news outlets.
Tesla Model 3 Makes 258 HP, EPA Filing Reveals - Motor Trend
It's a shame InsideEVs, or whoever tipped off InsideEVs isn't placing credit where credit's due (TMC), but I guess that's normal in the news biz.
Tesla Model 3 Makes 258 HP, EPA Filing Reveals - Motor Trend
It's a shame InsideEVs, or whoever tipped off InsideEVs isn't placing credit where credit's due (TMC), but I guess that's normal in the news biz.
Damn, we've gotten sucked into the vortex of capacity analysis, again. Folks! Pull up!
It's not about the capacity. It's about how far you can go for normal driving scenarios. (And also maybe a bit about the overall efficiency of wall-to-rubber power conversion to distance... but only if you're still not convinced EV cars are WAY MORE efficient than ICE and cheaper on fuel.)
I don't care if they shaved back the number of cells to make it *whatever* (kind of) capacity imagined or real, so long as it goes the distance as promised.
The question at hand here for model 3 is, what kind of motor/s has it got? And can they really call it a Tesla if it's got a PM motor.
Will you be driving a Tesla inspired Model 3 from a company who originally used Tesla designs and logo derived from such a motor, and now all it is is a crappy Model 3 "something" motor.. and, well, goes further than any other Tesla and OMG why did I spend $100K on a car that needs to stop at every supercharger when Model 3s are lapping me, hell ya, I'm getting a model 3 even if they aren't as fast. One day they will be just as fast, but not too soon, because Tesla. I think I just had a realization.
It's not about the capacity. It's about how far you can go for normal driving scenarios. (And also maybe a bit about the overall efficiency of wall-to-rubber power conversion to distance... but only if you're still not convinced EV cars are WAY MORE efficient than ICE and cheaper on fuel.)
I don't care if they shaved back the number of cells to make it *whatever* (kind of) capacity imagined or real, so long as it goes the distance as promised.
The question at hand here for model 3 is, what kind of motor/s has it got? And can they really call it a Tesla if it's got a PM motor.
Will you be driving a Tesla inspired Model 3 from a company who originally used Tesla designs and logo derived from such a motor, and now all it is is a crappy Model 3 "something" motor.. and, well, goes further than any other Tesla and OMG why did I spend $100K on a car that needs to stop at every supercharger when Model 3s are lapping me, hell ya, I'm getting a model 3 even if they aren't as fast. One day they will be just as fast, but not too soon, because Tesla. I think I just had a realization.
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SageBrush
REJECT Fascism
It wasn't TMC, it was you!
Best find of the year. By the way, how did you track it down ? I still cannot find the source
The only problem is that the EPA can't access the bricking buffer. As you posted above, 75.4 kWh usable would imply a charging efficiency of only 84%. That seems too low since the current gen is close to 90% efficient.
The EPA data seem to imply that the *usable* energy is closer to 80 kWh than 75 kWh.
Eh, I'm OK with TMC being referenced. Nothing at all is kind of annoying.
In terms of the info, it's all on the EPA website. When I was poking around the CA ARB site and found the Executive Order for the 3 LR, I noticed that they used the same test group numbers the EPA used. After reading TEG's post, I decided to do a little more digging. I initially looked for documents in the EPA's otaqpub, but I didn't find anything. The CSI is available now when you search for Tesla, but it wasn't available Saturday, probably because it hadn't been indexed yet.
Basic Search | Document Index System | US EPA
So.... I started to poke around on other parts of the EPA website, and found this page on certification, which is similar in format to the page the EPA has for fuel economy data. Luckily for me, the EPA had added the 3 to the spreadsheet of certified vehicles for 2017, so I knew they had received data from Tesla for certification.
Annual Certification Data for Vehicles and Engines | US EPA
I tried a *youknowwho* search with that test group, but naturally nothing came up. Then I tried searching for it using the EPA's search box, and hit gold.
On the plus side, it looks like all the certification pdfs use the same format, so once we have the test group number from the CA ARB, we can just check the EPA site with the new group number periodically, at least until the EPA restricts web access and/or changes their website directory structure.
Something else that will show up after the CSI, probably when Tesla starts selling the 3 to current owners, is the request for certificate of conformity, which will have even more solid info on the 3 and should look similar to what was submitted for the S/X.
https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=38162&flag=1
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Kind of off topic, but interesting nonetheless is the EPA data from the Rimac.
https://www3.epa.gov/otaq/datafiles/CSI-HRMAV0.00MDP.PDF
The power this car makes is nuts, but the range is pretty awful even though it has a larger pack than the 3 LR.
https://www3.epa.gov/otaq/datafiles/CSI-HRMAV0.00MDP.PDF
The power this car makes is nuts, but the range is pretty awful even though it has a larger pack than the 3 LR.
SageBrush
REJECT Fascism
I think the EPA certificate information lets us calculate the Monroney City and Highway MPGe in conjunction with the 126 MPGe combined fuel economy found elsewhere:
Combined is 55% city and 45% Highway
Cert UDDS is 495 miles
Cert Highway is 454.6 miles
So starting from the final MPGe of city = 1.22x of highway,
0.45x + 0.55*1.22*x = 126
Results in
113 MPGe Highway
138 MPGe City
Combined is 55% city and 45% Highway
Cert UDDS is 495 miles
Cert Highway is 454.6 miles
So starting from the final MPGe of city = 1.22x of highway,
0.45x + 0.55*1.22*x = 126
Results in
113 MPGe Highway
138 MPGe City
I agree that the EPA's numbers would indicate a max battery size of 80.5kWh but,weirdly Tesla's official numbers indicate that the battery sizes are ~54kWh and ~75kWh
The calculation to get there is charging at 240v and 40 amp (9600 Watts) provides 37 miles of charging per hour. With a range of 310 miles the total energy that we have to pull from the wall is 9600*310/37 = 80.4kWh. However the battery is not 100% efficient.
According to TeslaFi my efficiency when charging is 90% which I thing is about what Tesla uses.
This gives is a usable battery capacity of 72.3kWh. With a 2.7kWh buffer the battery is 75kWh.
For the low range we have 240V, 32Amp, 30miles/hour charge, 220 range giving a usable battery size of 50.7kWh. Adding a buffer gives ~53.5kWh.
The calculation to get there is charging at 240v and 40 amp (9600 Watts) provides 37 miles of charging per hour. With a range of 310 miles the total energy that we have to pull from the wall is 9600*310/37 = 80.4kWh. However the battery is not 100% efficient.
According to TeslaFi my efficiency when charging is 90% which I thing is about what Tesla uses.
This gives is a usable battery capacity of 72.3kWh. With a 2.7kWh buffer the battery is 75kWh.
For the low range we have 240V, 32Amp, 30miles/hour charge, 220 range giving a usable battery size of 50.7kWh. Adding a buffer gives ~53.5kWh.
SageBrush
REJECT Fascism
Errr ...
I should have written 12.5% charging losses, so 87.5% charging efficiency.
Yeah, the electrek article was updated with these disclaimers from Tesla.
New Tesla Model 3 details revealed by EPA: ~80 kWh battery pack, 258 hp, and more
I can see why they would reject the numbers they submitted to the EPA, since they're trying to maintain a balance between building the best possible mass market EV while also trying to encourage sales of the S/X. At the same time, unless they're going to submit different numbers for the 3 when they start selling to current owners, my feeling is those numbers are the closest we'll get to the truth with a capital t in terms of vehicle performance.
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SageBrush
REJECT Fascism
"Update: Tesla says that those numbers were for the EPA’s tests and our calculations doesn’t represent pack capacity."
I cannot even begin to parse this.
I cannot even begin to parse this.
I'm pretty sure that you can't use one battery for the EPA and another for the production car. It's not like Tesla is a German car company!
The battery must be 78kWh which means that some of the other numbers are wrong. Perhaps the miles per hour of charging assume no battery loss or there's actually an 8kWh buffer.
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