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Well, if the cooling tech is the same as in the 100 pack, there will be a smaller cooling to cell ratio. How many more 2170 cells might fit if we assume the cooling hoses are NOT scale up for bigger cells? I bet you can get an extra row, maybe 2, into the same pack. Ignoring the fact that it needs to happen within each of 16 modules, of course.
It was explained early on that the larger form factor would get less aluminium can material to contain more internals. I did the math on it recently, with typical sheet thinkness, etc, and came to 3% increase of density by floor space for cells alone. A smaller percentage of the floor being taken up by cooling might bump that a few more ticks. And then the 10-15% chemistry and 7.7% head space on top.
If Tesla cares, 125kWh will be reality soon enough. With such a big pack, a somewhat lower C rate doesn't really matter anymore.
Why? because the taper will be further ? So it can charge with no taper till 100kWh?
Cars have Cd quoted for them all over the place, but the Cd of any object changes quite a bit with the Reynolds Number and the Reynolds Number varies with velocity.
Additionally people often quote .24 or .25 for the Cd of the Model S. All those numbers pre-date the refresh in 2016. The range of the Model S went up a bit with the refresh which does indicate the probability that the actual drag of the current Model S is lower than the original. I suspect the new nosecone improves airflow over the entire car thus improving range a bit.
My degree is in Electronic Engineering, but we were required to take a number of Mechanical Engineering courses and aerodynamics was part of the Physics curriculum. I was also an Aeronautical Engineering major for a short time. I didn't have to get too deep into all the factors that affect aerodynamics and drag but I saw enough to know it isn't anywhere near as simple as people claim.
Even seasoned Aeronautical Engineers get it wrong sometimes. When I was at Boeing they were working on a new series of 737s (the original 737 flew in the late 1960s but they have extensively refreshed the design twice since, once in the late 80s and again in the last 10 years). They already had the longer body 737 in production and were working on a shortened version of the same model. When they put the shortened fuselage in a wind tunnel, things went horribly wrong. Just shortening the fuselage made the plane dangerously unstable because the airflow became wildly turbulent in unexpected ways and they had to go back and make changes to stabilize it.
Aerodynamics is a very complex thing. You need to look at a large number of different factors. Cars don't generally need to worry about aerodynamic stability like aircraft do, but there are many factors that affect drag and little things can have a big impact. I still think the Model 3 will have about 10-15% better range over the Model S for the same battery capacity.
In any case, getting back to the point of this thread, I see someone has ferreted out that the 4416 is actually the number of cells, which makes a lot more sense.
It gets more complicated with higher velocity. The velocities experienced in a car are pretty easy to work with. The formulas used aren't 100% accurate, but they are sufficiently accurate. It's a bit like using Newtonian physics vs relativistic physics. Usually Newtonian physics is more than accurate enough.
I think that number is too high. Even assuming no improvement in chemistry from the current cells in the Model S/X, that implies a pack of approximately 82.1 kWh gross, 78.1-79.7 kWh net. I suppose it's possible Tesla has gone backwards with regards to energy density, but I think it's odd. Of course, maybe Tesla has sacrificed energy density for charging speed, cost cutting, or something like that.
One thing can be said, and that is that 4416 is divisible with both 96 and 8. That speaks for this being a possibility. You'd have a 96s46p architecture, and potentially modules with 552 cells. This is a scenario that's a lot more probable than the cell format being 4416.
I guess we just have to wonder if this person is in the loop or not.
Ignoring the fact that there are 16 modules is a mistake, looking at circle packing - you will be able to cover a smaller area of a rectangle with larger circles. With 16 rectangles, a lot of space will be wasted along the sides. Though, assuming they redesign the pack entirely with regards to number of modules, it may be possible to fit in some more cells. (This could of course also be done with 18650-cells.)
JeffK
Well-Known Member
Although, if everyone followed the standard then we wouldn't have confusion either...
SageBrush
REJECT Fascism
I mean, a theoretical 4416 battery is actually a pancake...
I think whoever came up with 4416 being cell count is a genius and makes me think that on Friday only large battery options will be available. I love battery speculation so here goes my calculations;
2170 cell: 3.7V nominal as always, 4600mAh (mAh capacity of the new cell will be important)
For a 400V pack we need 96 cells in series. In Model S this is 6 groups of 16 modules. If you rewatch the original reveal where Model 3 was revealed from ground up showing battery, chassis, body etc. you can almost see there are 8 modules. Meaning they will have 12 groups in series in each module. So 4416/96 (12*8) = 46 cells in parallel per group. So like Model S' 74p6s16s, Model 3 will be 46p12s8s
46p = 4600mAh x 46 = 211Ah.
3.7V * 96 in series makes the nominal voltage 355V.
211Ah * 355V = 74,9kWh with 72,5kWh usable. Yielding 285mi EPA.
And for the smaller pack they can just remove two modules. This will reduce the voltage a lot as every module in this setup is 44V unlike 22V of Model S. So 46p12s6s would be 56,3kWh however @265V nominal. 303V when @100%. ~270V supercharging voltage @250-300Amps would be 70kW. That is slow in mph but in relative terms, waiting time will be the same for same %. Only with a faster supercharging pack you will get more miles per time yet same % per time. I think this makes sense as it would further differentiate Model 3 with Model S. Also 5.6 second acceleration is quite possible with 230kW power I think if my i3 can do <7 secs with 125kW. To get 230kW it would need 900-1000amps under acceleration. Considering Tesla has been feeding 1762Amps to P100D, 1000Amps should be piece of cake.
Let's see if I'm correct on Friday! I was correct with guessing the architecture of the new 100kWh pack.
2170 cell: 3.7V nominal as always, 4600mAh (mAh capacity of the new cell will be important)
For a 400V pack we need 96 cells in series. In Model S this is 6 groups of 16 modules. If you rewatch the original reveal where Model 3 was revealed from ground up showing battery, chassis, body etc. you can almost see there are 8 modules. Meaning they will have 12 groups in series in each module. So 4416/96 (12*8) = 46 cells in parallel per group. So like Model S' 74p6s16s, Model 3 will be 46p12s8s
46p = 4600mAh x 46 = 211Ah.
3.7V * 96 in series makes the nominal voltage 355V.
211Ah * 355V = 74,9kWh with 72,5kWh usable. Yielding 285mi EPA.
And for the smaller pack they can just remove two modules. This will reduce the voltage a lot as every module in this setup is 44V unlike 22V of Model S. So 46p12s6s would be 56,3kWh however @265V nominal. 303V when @100%. ~270V supercharging voltage @250-300Amps would be 70kW. That is slow in mph but in relative terms, waiting time will be the same for same %. Only with a faster supercharging pack you will get more miles per time yet same % per time. I think this makes sense as it would further differentiate Model 3 with Model S. Also 5.6 second acceleration is quite possible with 230kW power I think if my i3 can do <7 secs with 125kW. To get 230kW it would need 900-1000amps under acceleration. Considering Tesla has been feeding 1762Amps to P100D, 1000Amps should be piece of cake.
Let's see if I'm correct on Friday! I was correct with guessing the architecture of the new 100kWh pack.
Or remove one module, leaving a 65kwh (63kwh usable) pack, for a (Bolt-beating) 249 miles EPA.
JeffK
Well-Known Member
I cannot imagine their 2170 has a lower capacity than samsung's 21700s at 4750 mAh, especially with Elon boasting about having the highest energy density cell.
18650's were 3400 or 3500mAh? 2170's are said to be 5750-6000mAh. 4600mAh seems like a small step up for a bigger step up in size?
In case of steel, the density increase from the larger form factor would only be more signficant.
All the sources I could find (including this site) offer aluminium, steel is never mentioned as a component. What is your source, if I may ask?
In case of steel, the density increase from the larger form factor would only be more signficant.
Original Model S cells were around 3000-3100mAh
90D packs got to 3300mAh and 100 pack uses the same 3300-3350mAh cells in a different config.
I believe the most we'll get out of the new cells would be 4800mAh. Only volume increase to existing chemistry will be 4600mAh. However they might pull back on 7% yearly density improvements because they want less heat, less IR with this cell as new geometry makes it slightly slower to cool down.
Recalculation for 4700mAh makes it 76,7kWh. Which would be a ~73kWh usable. A theoretical Model 3 75D can cruise on the highway at 120km/h-130km/h, with less surface area, smaller footprint and better aero 180Wh/km isn't a dream. 73kWh/180Wh = 400km on the highway. That would be incredible. Coming from my poor 19kWh i3 I drool over that idea.
For comparison a 3 year old Model S 85 usually has 74-75kWh usable energy because of the 85kWh labeling fail that no one likes mentioning. And at 130kph a Model S would consume at least 220Wh/km. 74000/220 = 335km on the highway. 300km comfortable before reaching the 'red' battery levels. Versus a Model 3 75D's 360-370km comfortable highway speed range. If anything the 180Wh/km figure I used is conservative. New Hyundai Ioniq EV roughly the same size as Model 3 gets as low as 140Wh/km on the highway. That would be 520km highway range with the Model 3! Also Model 3 can be more efficient than the Ioniq. Very eager to see results.
Hi, @wdolson. If you want, feel free to enter your EPA rated range estimate for the longest range Model 3 here. This is for the AWD, larger battery version that is expected to begin production in January. @Yggdrasill has already voted in that poll. Also, that poll is part of a larger predictions competition. The thread about that is here: Tesla Predictions Competition
By the way, I agree with the idea that 4416 is probably the cell count. I have done the calculations and it makes sense. Tesla has been working on the ideal form factor for years. Elon said they have done lots of modeling to come up with the ideal cell size. Listen here after 26:25.
By the way, I agree with the idea that 4416 is probably the cell count. I have done the calculations and it makes sense. Tesla has been working on the ideal form factor for years. Elon said they have done lots of modeling to come up with the ideal cell size. Listen here after 26:25.
A 65 versus 75 kWh version doesn't seem to offer much in the way of range differentiation.
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