A little spreadsheet trying to explain/conceptualize why things are the way they are

[No2DinosaurFuel]

Since the unveil I've heard so many people disappointed with;

• Slow supercharging of the 3
• Lower than expected performance values for the 3
• Expensive options for the 3

etc. etc.

So trying to understand what they made with the 3 I plotted a spreadsheet explaining cells, pack architecture they used and supercharging speeds. We already know about the old S and X packs and their supercharging speeds. And last week we found out there were 4416 cells with the range version of the 3. Rest is all speculation but I think it makes sense. Correct me if I'm wrong or you have anything to add. I just love geeking out on technicalities like this. Here's the spreadsheet for your liking;


Notes;

• As you can see standard Model 3 will have a very low voltage pack. Whereas most packs have 400V and 75 pack has 350V right now. Standard Model 3 pack will have a 300V pack. Meaning the same amperage when charging and driving will yield less kW i.e. power.
• That is why I think the spreadsheet shows the standard 3 to be slightly less efficient than the range one. I believe under acceleration packs will feed around 750-800Amps to the inverter. However because Tesla didn't want a slower than 6 sec. 0-60 car on the standard one they need more amps with standard due to less voltage. This might make it less efficient.
• This also explains why they're coming out with the 400V pack first. More time to test the 300V system as it is the first time they're building something with this low voltage.
• As for supercharging. You can see this past 4 years Tesla (up to 50%) had 1.05-1.1C supercharging with their chemistry. Figuring out the numbers from what we are given shows the same C rates for the 3. I would expect less since 2170, due to geometry, suffers from a less efficient heat dissepation. Yet apparently Tesla has made the pack cooling better with their new architecture, sustaining the same C rates. If anything they're pushing the standard pack to its limits. (I got the supercharging average power from various supercharging graph and videos I found online. They seem to check out.)
• I'm so glad Tesla gave up on faux battery labeling. This has been discussed thoroughly but it is very clear old 85 and 90 packs are not 85 and 90. New 75, 100 packs give what they promised. Hell a 3 year old 85 can have the same capacity as a brand new 75 now even.
• It astonishes me how much easier and cheaper pack building must have become with new cell geometry. ~2600 less needed for same capacity. For both terminals this means 5200 less holding or PCBs or whatever they're doing. Must have decreased the dead weight in pack as well.

So to sum it all up I don't think Tesla is purposefully throttling Supercharging speed with the 3 to make S better value. If anything they're giving it their most. Also it will be very interesting if 75 indeed turns out to be more efficient than 55. OR 75 won't have 316 EPA but ~300 EPA. (Since they advertise standard to be 220mi EPA yet 310 mi non EPA for range pack)


Thoughts?

long range model 3 can't be more efficient than the short range version. Something is definitely wrong. It's a heavier car. Unless Tesla purposely made the short range less efficient which i highly doubt.

If you like the 55KWh for the short range tesla, then it has to be 80KWh or 85KWh pack. I suspect it will be the 85KWh they are using in the software limited Model S75D. But if it's 85KWh, then it is most likely a 60KWh.

 

[Ulmo]

Someone from the inside reported that 4416 cells were going to be used with the 3 in terms of geometry. However we know they made the whole gigafactory based on 2170 geometry and 4416 cell would be a pancake cell, rendering all of Tesla's experience with 100s of thousands of S-X invaluable. Just makes zero sense.

Then, someone genious tested the idea that there can be 4416 cells. Math checks out incredibly well with capacity and range. It is in no way confirmed but would be more surprising if it was something different.

English is far from that precise; I bet the information being passed around that you caught hold of was from foreigners, because no English speaker would read "4416 cells" and think 44x16; they'd think it was a count, because of reasonable interpretations. Other languages can define what they're saying more precisely. It's a part of why it takes twice as long to explain something in Spanish than English, for instance; the concepts are identical, but the language is much more precise and means something totally different.

 

[emir-t]

English is far from that precise; I bet the information being passed around that you caught hold of was from foreigners, because no English speaker would read "4416 cells" and think 44x16; they'd think it was a count, because of reasonable interpretations. Other languages can define what they're saying more precisely. It's a part of why it takes twice as long to explain something in Spanish than English, for instance; the concepts are identical, but the language is much more precise and means something totally different.

Yeah but if your case is a battery electric vehicle manufacturer then you might think 44-16. (Forty four, sixteen). Just like you 18650 and 2170. Calculations check ournperfectly too. Yet I don't know about the three module remarks from few. I guess we're going to have to wait and see.

 

[LargeHamCollider]

It's pretty clear from range figures and the C and D comment that the ratio of capacities is 3/2 with the big pack being ~75kWh and the small pack being ~50kWh. The more interesting question is voltages.

Also there's a 0% probability that Tesla is using 44160 cells! Zero percent! If anyone would like to place a small wager on this I'm willing to bet.

 

[calisnow]

English is far from that precise; I bet the information being passed around that you caught hold of was from foreigners, because no English speaker would read "4416 cells" and think 44x16; they'd think it was a count, because of reasonable interpretations. Other languages can define what they're saying more precisely. It's a part of why it takes twice as long to explain something in Spanish than English, for instance; the concepts are identical, but the language is much more precise and means something totally different.

There have been numerous other posts saying that in fact this rumored "4416" cell is 44X16. This is not a case of the OP or other "foreigners" not understanding the English language. I believe this rumor started with Teslanomics and then was printed by Teslarati:

Tesla could be using a "4416" battery cell in Model 3 and next-gen S, X fleet

"The news comes to us from Ben Sullins at Teslanomics who received an insider tip that Tesla has produced a significantly larger cylindrical battery cell that’s roughly 44mm in diameter and 160mm in height"

 

[Yggdrasill]

Any thoughts on this statement from Car & Driver?

"The battery pack has three modules instead of the 16 present in the Model S."

Stand and Deliver: Elon Musk Hands Off First Tesla Model 3 Production Cars

Three and two modules works pretty well, capacity wise.

With the larger pack being something like 237 Wh/mile x 310 miles + 4.0 kWh = 77.5 kWh, the smaller pack would be 77.5 kWh x 2 / 3 = 51.7 kWh.

With an unavailable margin of 2.4 kWh, that leaves 49.3 kWh available. Over 220 miles, that results in 224 Wh/mile, or 5.5% lower consumption than the assumed consumption of the larger pack.

Does this make sense?

Well, the aero should be identical, but the base version will be lighter. Long range version is specified at 3814 lb and the base is specified at 3549 lb. If we add 180 lb for the driver, that's a 6.7% reduction in weight. It's certainly in the ballpark.

 

[SageBrush]

Well, the aero should be identical, but the base version will be lighter. Long range version is specified at 3814 lb and the base is specified at 3549 lb. If we add 180 lb for the driver, that's a 6.7% reduction in weight. It's certainly in the ballpark.

Both cars would presumably have a driver.
The Gross weight difference of 120 Kg works out to 10.5 N in a car that has ~ 400 N at highway forces and about half that amount at city speeds.

 

[No2DinosaurFuel]

Here is my numbers all based on Tesla's advertising of 1 hour charging and how far the model 3 will go.

Short range Model 3:
Volt: 240V
Amp: 32A
Hour: 1 hour
range gained: 30 miles
wh/mile: 256 wh/mile
charging efficiency: 90%
driving efficiency: 230.4 wh/mile
total Range: 220
usable KWh: 50.7KWh
Likely KWh: 53.2KWh

Long range Model 3:
Volt: 240V
Amp: 40A
Hour: 1 hour
range gained: 37 miles
wh/mile: 259.5 wh/mile
charging efficiency: 90%
driving efficiency: 233.5 wh/mile
total Range: 310
usable KWh: 72.4KWh
Likely KWh: 74.9KWh

Just some more info for food for thoughts:
KWh difference between the 2 model: 21.7KWh

Price for KWh of lithium battery according to electrek:
$227/kwh as of Jan 30th.
21.7KWh = $4925.90

So there is a $4000 mark up if you are using January's number. I suspect it is more since Tesla's cost is probably lower and this is July vs Jan.

 

[LargeHamCollider]

Three and two modules works pretty well, capacity wise.

With the larger pack being something like 237 Wh/mile x 310 miles + 4.0 kWh = 77.5 kWh, the smaller pack would be 77.5 kWh x 2 / 3 = 51.7 kWh.

With an unavailable margin of 2.4 kWh, that leaves 49.3 kWh available. Over 220 miles, that results in 224 Wh/mile, or 5.5% lower consumption than the assumed consumption of the larger pack.

Does this make sense?

Well, the aero should be identical, but the base version will be lighter. Long range version is specified at 3814 lb and the base is specified at 3549 lb. If we add 180 lb for the driver, that's a 6.7% reduction in weight. It's certainly in the ballpark.

I think this is right, also I suspect Tesla is sandbagging the range of the long range model. That would explain the somewhat high efficiency delta and the "315 miles" that showed on the screen of one of the newly delivered M3s.

 

[Troy]

wh/mile: 256 wh/mile

Where does the 256 Wh/mi number come from?

 

[No2DinosaurFuel]

Where does the 256 Wh/mi number come from?

Got it from taking 240V * 32A and getting wh. Tesla has stated that will get the model 3 to 30 miles.

240*32= 7.68Kwh
7.68kwh/30 = 256wh/mile.

 

[Electroman]

I don't believe the longer range will really have an EPA of 315. These range numbers are guesstimates and Tesla is over promising on the range..