JRP3
Hyperactive Member
Especially not in the base model, since the larger pack options will far out do the Bolt in both capacity and range.
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Especially not in the base model, since the larger pack options will far out do the Bolt in both capacity and range.
Reciprocity
Active Member
@scaesare
"The larger cells actually represent the slightly lesser volume... but by the time you figure the amount of casing material as opposed to actual cell chemistry, overhead for cooling, other pack logistics, etc... it ends up a wash."
My point was that the new cells are clearly a much larger internal volume, unless the casing is MUCH thicker. I dont believe that to be the case. The higher volume of internal space would mean a lot more active materials and less weight when compared to the older cells/pack configuration.
Again, its very clear that there will be a dramatic increase in efficiency, Wh per Kg of battery pack. As an example, I point to PW1 vs PW2. It adds up to about 30% more KWh for the same weight and volume at the pack level.
This does not explain why they couldn't fit a 100KWh pack in the Model 3 or 120Kwh+ pack in S/X. Maybe the thought is that it just isn't necessary. My guess is that they will put the new cells in the S/X with a 100Kwh max and the range will be around 400 miles. They will then say that is good enough and turn their focus on making the cells less expensive and focus on improving the efficiency of the rest of the drive train. Not to say that they will stop improving batteries, but they will be doing so with the next models in mind. Roadster, Truck, Van, Bus and Semi. Maybe even a compact/sub-compact for the masses.
"The larger cells actually represent the slightly lesser volume... but by the time you figure the amount of casing material as opposed to actual cell chemistry, overhead for cooling, other pack logistics, etc... it ends up a wash."
My point was that the new cells are clearly a much larger internal volume, unless the casing is MUCH thicker. I dont believe that to be the case. The higher volume of internal space would mean a lot more active materials and less weight when compared to the older cells/pack configuration.
Again, its very clear that there will be a dramatic increase in efficiency, Wh per Kg of battery pack. As an example, I point to PW1 vs PW2. It adds up to about 30% more KWh for the same weight and volume at the pack level.
This does not explain why they couldn't fit a 100KWh pack in the Model 3 or 120Kwh+ pack in S/X. Maybe the thought is that it just isn't necessary. My guess is that they will put the new cells in the S/X with a 100Kwh max and the range will be around 400 miles. They will then say that is good enough and turn their focus on making the cells less expensive and focus on improving the efficiency of the rest of the drive train. Not to say that they will stop improving batteries, but they will be doing so with the next models in mind. Roadster, Truck, Van, Bus and Semi. Maybe even a compact/sub-compact for the masses.
Hi. I've just completed the most detailed battery size vs range calculation I have done so far. First, let me show you the results:
The calculation includes weight, drag coefficient and drag area. You can find all the details here. I've included all possible battery sizes so you can see what the EPA rated range would be if the Model 3 was released with that battery size. Especially people who are suggesting 80, 85, 90, 95 kWh packs for the Model 3, should look at these range numbers first because the Model 3 90D would have 353 mi and the Model 3 95D, 370 mi EPA rated range. That's a lot more than the Model S 100D. 90 or 95 kWh packs are not going to happen unless Tesla plans to release 110 or 120 kWh Model S versions before July 1, 2017. However, Elon said twice they won't do that:
16 Sep 2016: Elon Musk on Twitter Quote: Elon: I think we will probably stop at 100 kWh on battery size.
07 Feb 2017: Elon Musk on Twitter Quote: Elon: No plans to take X, S (or 3) above 100 kWh. Semi necessarily and pickup truck maybe will go above.
People sometimes assume that we don't know anything about the Model 3. Therefore everything is just a guess. This is not correct. We know a lot. For example, we know the dimensions of the Model 3 because Motor Trend has published that data. We also know the dimensions of the Model S and we know the weight of almost all Model S variants. Therefore, I was able to calculate the weight of different Model 3 variants. Here are the results:
Model 3 Curb weight
Model 3 55 1720 kg
Model 3 75 1809 kg
Model 3 55D 1777 kg
Model 3 75D 1866 kg
Model 3 P75D 1882 kg
To calculate that first I created a table that shows the weight of all Model S variants. Then I subtracted the weight of the following items.
If we assume the same ratio for the Model 3, it should weigh 8.814*153.38= 1352 kg without motors and the battery. It is possible to argue that the Model 3 should weigh more per square meter because it will have a steel frame instead of aluminum. However, the Model 3 won't have a dashboard, no second computer to power the dashboard and only 1.5km wiring instead of 3km. So I think these will balance out the steel vs aluminum frame weight difference.
After that, I calculated and added back the pack weight for different size Model 3 packs. I have considered the fact that 2170 cells have more energy density (more kWh per kilogram). Also, I considered things like the weight of the pack housing vs the modules. WK057 said HERE the pack housing weighs 250 lb (114 kg). In addition, WK057's battery pack kWh numbers he mentioned here were also part of the calculation. In other words, I made this calculation as detailed as possible.
The calculation includes weight, drag coefficient and drag area. You can find all the details here. I've included all possible battery sizes so you can see what the EPA rated range would be if the Model 3 was released with that battery size. Especially people who are suggesting 80, 85, 90, 95 kWh packs for the Model 3, should look at these range numbers first because the Model 3 90D would have 353 mi and the Model 3 95D, 370 mi EPA rated range. That's a lot more than the Model S 100D. 90 or 95 kWh packs are not going to happen unless Tesla plans to release 110 or 120 kWh Model S versions before July 1, 2017. However, Elon said twice they won't do that:
16 Sep 2016: Elon Musk on Twitter Quote: Elon: I think we will probably stop at 100 kWh on battery size.
07 Feb 2017: Elon Musk on Twitter Quote: Elon: No plans to take X, S (or 3) above 100 kWh. Semi necessarily and pickup truck maybe will go above.
People sometimes assume that we don't know anything about the Model 3. Therefore everything is just a guess. This is not correct. We know a lot. For example, we know the dimensions of the Model 3 because Motor Trend has published that data. We also know the dimensions of the Model S and we know the weight of almost all Model S variants. Therefore, I was able to calculate the weight of different Model 3 variants. Here are the results:
Model 3 Curb weight
Model 3 55 1720 kg
Model 3 75 1809 kg
Model 3 55D 1777 kg
Model 3 75D 1866 kg
Model 3 P75D 1882 kg
To calculate that first I created a table that shows the weight of all Model S variants. Then I subtracted the weight of the following items.
- rear motor,
- front motor, front inverter, front gear box
- battery pack
If we assume the same ratio for the Model 3, it should weigh 8.814*153.38= 1352 kg without motors and the battery. It is possible to argue that the Model 3 should weigh more per square meter because it will have a steel frame instead of aluminum. However, the Model 3 won't have a dashboard, no second computer to power the dashboard and only 1.5km wiring instead of 3km. So I think these will balance out the steel vs aluminum frame weight difference.
After that, I calculated and added back the pack weight for different size Model 3 packs. I have considered the fact that 2170 cells have more energy density (more kWh per kilogram). Also, I considered things like the weight of the pack housing vs the modules. WK057 said HERE the pack housing weighs 250 lb (114 kg). In addition, WK057's battery pack kWh numbers he mentioned here were also part of the calculation. In other words, I made this calculation as detailed as possible.
JRP3
Hyperactive Member
Doesn't seem correct that you get the same rating for the Model 3 as the EPA for the taller, poor cd Bolt.
Where did you get your numbers for energy density?
That assumes that the Model 3 can't have a higher range than a Model S. Which is just completely unjustified.
Thank you kindly
Well yeah. They are larger, of course they represent more volume. Nobody is disputing that. By footprint alone (not height), the 21mm cells represent 36% additional volume over an 18mm cell. That was stated in my post.
However because each cell is larger, there are fewer of them. That roughly cancels out within the pack enclosure to end up with about he same volume of cell material for a given pack footprint.
Now if we want to be even more exact and consider the amount of volume attributable to casing, the surface area of a cell is a function of it's diameter and height. If we ignore height differences, then:
(21mm*3.14)/(18mm*3.14) = 17% more casing material for the larger cells, despite 36% more volume (assuming identical cell heights and casing thickness). So the larger cells are slightly more efficient from that standpoint also.
The PW chemistry is not the same as the automotive cell chemistry, so we don't know what the gains will be, but indeed JB has referred to ~30% gain over original Model S chemistry (not the most recent chemistry step)
The pack not being big enough explains that. That's what Elon says, and it's the simplest explanation.
100kWh doesn't deliver 400 miles in S/X today. Why would it with 100kWh delivered via different cells[/QUOTE]
Ok my speculation 
If you look at reveal it shows 8 big modules. If it true then its no longer current 14 + 2 configuration, so the reason why it can't have big battery because it has to fit in area which is smaller than current 75 kWh pack. Now the reasoning why 8 different size modules versus current 14 or 16:
current setup lower pack is only 12,5% smaller, but it is too small percentage diffence, so they need 2 different size modules, it cost slightly more but that way they can use same motor config (same voltage)
faster supercharging at low SOC if chemistry is capable.
If you look at reveal it shows 8 big modules. If it true then its no longer current 14 + 2 configuration, so the reason why it can't have big battery because it has to fit in area which is smaller than current 75 kWh pack. Now the reasoning why 8 different size modules versus current 14 or 16:
current setup lower pack is only 12,5% smaller, but it is too small percentage diffence, so they need 2 different size modules, it cost slightly more but that way they can use same motor config (same voltage)
faster supercharging at low SOC if chemistry is capable.
Reciprocity
Active Member
@scaesare
"100kWh doesn't deliver 400 miles in S/X today. Why would it with 100kWh delivered via different cells"
Because its 30% lighter for the same KWh, and I know this because PW1 vs PW2 were its easy to calculate that 2x KWh for a slightly heavier and larger package. Really surprised that very few people see that weight is almost as important as KWh in determining range. The pack is by far the heaviest component in the car.
"Well yeah. They are larger, of course they represent more volume. Nobody is disputing that. By footprint alone (not height), the 21mm cells represent 36% additional volume over an 18mm cell. That was stated in my post."
I am not talking about individual cells volume, that is obvious. I am talking about your image that clearly shows the lower number of cells has more internal volume then the larger number of cells in the same space. Your original post said that there was actually less volume from the larger cells when you put them into a module as compared to a larger number of smaller cells in a module that is the same size.
"The pack not being big enough explains that. That's what Elon says, and it's the simplest explanation."
Elon said that in relation to the 3 and shorter wheelbase/width, not the S/X. He just said that they wouldn't go above 100 in the S/X.
"100kWh doesn't deliver 400 miles in S/X today. Why would it with 100kWh delivered via different cells"
Because its 30% lighter for the same KWh, and I know this because PW1 vs PW2 were its easy to calculate that 2x KWh for a slightly heavier and larger package. Really surprised that very few people see that weight is almost as important as KWh in determining range. The pack is by far the heaviest component in the car.
"Well yeah. They are larger, of course they represent more volume. Nobody is disputing that. By footprint alone (not height), the 21mm cells represent 36% additional volume over an 18mm cell. That was stated in my post."
I am not talking about individual cells volume, that is obvious. I am talking about your image that clearly shows the lower number of cells has more internal volume then the larger number of cells in the same space. Your original post said that there was actually less volume from the larger cells when you put them into a module as compared to a larger number of smaller cells in a module that is the same size.
"The pack not being big enough explains that. That's what Elon says, and it's the simplest explanation."
Elon said that in relation to the 3 and shorter wheelbase/width, not the S/X. He just said that they wouldn't go above 100 in the S/X.
Hi, @JRP3. The short answer is, EPA tests are performed at 32 mph average speed. Therefore air drag has very little effect.
I have added the Chevy Bolt to column B here. The Bolt weighs 1624 kg (source) and has 0.32 drag coefficient (source). I have left the frontal area the same as the Model 3. The Bolt has 238 mi EPA rated range. The model I'm using now (I've updated this after your message) shows 236 mi. That's pretty close. Therefore, I will assume that it is accurate. Here are the new range numbers. These are slightly different than what my previous message shows:
Here is what happened: I have two variables that I need to adjust until the calculated Model S range numbers match the actual Model S EPA rated range numbers. These variables are speed and road friction. What I did was, I entered 64 mph to speed and then I adjusted the road friction until the calculated range matched the EPA range. The problem was, EPA tests are performed at much lower speeds.
After a little research, I found the speed numbers HERE, under the test details tab. EPA uses 5 different test cycles. The average speed in each cycle is as follows:
21.20 mph
48.30 mph
48.40 mph
21.20 mph
21.20 mph
The average of all 5 cycles is 32.1 mph. I was using 64 mph. After I changed speed to 32.1 mph, I adjusted the road friction variable and suddenly Bolt's calculated range increased from 197 to 236 miles. That means the current model looks OK to me. Look at cells B3:C20 to make sure I'm not cheating. I'm using all the same variables for the Model 3 and Chevy Bolt except Bolt's actual weight and drag coefficient. The sheet correctly calculates all Model S range numbers and the Chevy Bolt range number to match the actual EPA range. There are 3 sets of road friction numbers: One for the single motor, one for dual motor and one for performance. This variable includes things like motor efficiency. Basically, when the calculation closes for all single motor Model S variants, I take the road friction variable and use it for the Model 3 single motor versions. That's why I entered lots of Model S data.
I have added the Chevy Bolt to column B here. The Bolt weighs 1624 kg (source) and has 0.32 drag coefficient (source). I have left the frontal area the same as the Model 3. The Bolt has 238 mi EPA rated range. The model I'm using now (I've updated this after your message) shows 236 mi. That's pretty close. Therefore, I will assume that it is accurate. Here are the new range numbers. These are slightly different than what my previous message shows:
Here is what happened: I have two variables that I need to adjust until the calculated Model S range numbers match the actual Model S EPA rated range numbers. These variables are speed and road friction. What I did was, I entered 64 mph to speed and then I adjusted the road friction until the calculated range matched the EPA range. The problem was, EPA tests are performed at much lower speeds.
After a little research, I found the speed numbers HERE, under the test details tab. EPA uses 5 different test cycles. The average speed in each cycle is as follows:
21.20 mph
48.30 mph
48.40 mph
21.20 mph
21.20 mph
The average of all 5 cycles is 32.1 mph. I was using 64 mph. After I changed speed to 32.1 mph, I adjusted the road friction variable and suddenly Bolt's calculated range increased from 197 to 236 miles. That means the current model looks OK to me. Look at cells B3:C20 to make sure I'm not cheating. I'm using all the same variables for the Model 3 and Chevy Bolt except Bolt's actual weight and drag coefficient. The sheet correctly calculates all Model S range numbers and the Chevy Bolt range number to match the actual EPA range. There are 3 sets of road friction numbers: One for the single motor, one for dual motor and one for performance. This variable includes things like motor efficiency. Basically, when the calculation closes for all single motor Model S variants, I take the road friction variable and use it for the Model 3 single motor versions. That's why I entered lots of Model S data.
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alseTrick
Active Member
What difference does it matter if it has a 55kWh battery and a range of 220 miles? If people don't like it, they can go buy something else.
Tesla only makes money when consumers buy Tesla.
No, you really don't. Unless you have disassembled one from each generation, you don't know what's in there, nor what version of the cells were being used. If 2170s had nearly twice the energy density of current 18650s, it would be a huge deal, and Tesla would be taking advantage of it.
It doesn't though. They are only different by a few percent (and in the other direction). The picture is not of a scale where that would be visible. Do the actual math.
Generally the solution for packing relatively small cylinders in a rectangle is understood, and density doesn't vary much based on cylinder size.
He also said that they had used all the available room. They could add more in the frunk, but that is what he was disclaiming.
Thank you kindly.
alseTrick
Active Member
All I know is it would be a bad look if the 3 offered the same battery as the Bolt but the Bolt had a larger range.
Reciprocity
Active Member
"No, you really don't. Unless you have disassembled one from each generation, you don't know what's in there, nor what version of the cells were being used. If 2170s had nearly twice the energy density of current 18650s, it would be a huge deal, and Tesla would be taking advantage of it."
First, I never said, nearly twice. The specs for the PW1 and PW2 are public information. 7KWh vs 13.5KWh. Dimensions are known, weight is known. Unless PW1 was made partially of inert led, PW2 is 30% more Wh per kg. Yes, I am making some assumptions, but unless you do tear apart the packs and individual units, we are all just speculating. I am pretty sure they did not make PW1 extra heavy for no reason and PW2 extra light because of magic.
First, I never said, nearly twice. The specs for the PW1 and PW2 are public information. 7KWh vs 13.5KWh. Dimensions are known, weight is known. Unless PW1 was made partially of inert led, PW2 is 30% more Wh per kg. Yes, I am making some assumptions, but unless you do tear apart the packs and individual units, we are all just speculating. I am pretty sure they did not make PW1 extra heavy for no reason and PW2 extra light because of magic.
Reciprocity
Active Member
"All I know is it would be a bad look if the 3 offered the same battery as the Bolt but the Bolt had a larger range."
Not really, the bolt is small and ugly. Can the bolt supercharge? Can the bolt get you date? Maybe, but not likely. Bolts are available now, there are not 400,000+ people waiting for them. Also, there is no upgrade for the bolt battery and we have no idea what the endurance of that pack will be.
Not really, the bolt is small and ugly. Can the bolt supercharge? Can the bolt get you date? Maybe, but not likely. Bolts are available now, there are not 400,000+ people waiting for them. Also, there is no upgrade for the bolt battery and we have no idea what the endurance of that pack will be.
No, you said:
Care to enlighten us on those easy calculations instead. Because that sure looks like 'nearly twice' to me.
Not magic, engineering.
And you still don't know which generations of battery you are comparing.
Thank you kindly.
JRP3
Hyperactive Member
Different cell chemistry than used in vehicles, so no correlation is possible.
Height increase highly increases energy density at pack level, think of massive pack area it remains the same only height increases by 5mm. But I have no idea how much might cell caps weight so can't calculate increases for height, but my guess would be less then 5% at cell level.
Edit: somebody needs dissasambled current Tesla cell and weight its parts to make more precise gravimetric density calculations posssibly
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This is an awkward, out-of-order, posting style, so I'm not going to try to disassemble it, I'll just respond to points within it:
- Impact of weight on range: If you think a few hundred pounds less of pack mass (the batteries only make up a little more than half of the pack weight) is going to add another ~20% more range, I believe you are sorely mistaken. The difference between my driving my S 85 by myself, and with another 800 lbs of additional passengers and luggage is almost indiscernible in mixed driving. I'll give you maybe a couple of percent, but that's it.
- Cell volume: I provided the numbers. Total packing has the two sizes within 2% of each other.
- Max Model 3 Pack size: I was responding to this direct quote from you: "This does not explain why they couldn't fit a 100KWh pack in the Model 3". Elon did explain why: pack size constraints.
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