Predicting Battery Sizes

[ChiefRollo]

I believe there will be two battery sizes for the CT lineup, 200 KWH and 125 KWH for the top 3-motor tier and two bottom two-motor tiers respectively. Made of 4850 cells, Tesla will deliver as promised years ago, 500+ and 300+ miles for the two (battery-driven) tiers.

 

[scottf200]

Lot of discussion on fitting 4680 cells. And the physical space required to go from 125 up to 200 kWh.
Yours sounds like a gut feel

 

[AlanSubie4Life]

I had some questions in the other thread, this is probably a better place to answer them though:

I doubt we will get this answered today.
Launch is Imminent

125kW seems about right for 300-340 miles, depending on tire choice. Hopefully we’ll at least find that out but I doubt it.

No one will take the required picture. I wonder if the truck will have the energy screen? That’s all we need…

 

[ChiefRollo]

Lot of discussion on fitting 4680 cells. And the physical space required to go from 125 up to 200 kWh.
Yours sounds like a gut feel

As it has to do with mine, it’s a big gut feel.

 

[ChiefRollo]

I had some questions in the other thread, this is probably a better place to answer them though:

I doubt we will get this answered today.
Launch is Imminent

125kW seems about right for 300-340 miles, depending on tire choice. Hopefully we’ll at least find that out but I doubt it.

No one will take the required picture. I wonder if the truck will have the energy screen? That’s all we need…

Think we will…today. I’m not sure about the energy screen; I’ve become used to it on my S.

 

[AlanSubie4Life]

Nope, no info. 250kW max charging rate for now. Presumably will change.

 

[AlanSubie4Life]

So about 131kWh.

42.9kWh/100mi * 340mi * 0.9

 

[scottf200]

View attachment 995211
So about 131kWh.

42.9kWh/100mi * 340mi * 0.9

Where did that graphic come from? Presentation? Tesla site?
Is 131 kWh supposed to be total or usable. What is the 0.9 or 90% multiple for?

131 * 95% = 124.45
131 * 94% = 123.14
131 * 93% = 121.83
131 * 90% = 117.9

 

[AlanSubie4Life]

Where did that graphic come from? Presentation? Tesla site?

Tesla website if you dive into the fine print for their gas savings price reduction.

Is 131 kWh supposed to be total or usable.

Usable. Including buffer. So basically it is the pack size (I don’t know what total means here - they always run packs until they stop working. And Tesla doesn’t do any pack buffering to prevent actual range loss.)

What is the 0.9 or 90% multiple for?

Charging efficiency. Historically it has been about 0.88 or 0.89.

So maybe it is 128kWh! I just rounded to 0.9. I think it is unlikely it will be any less than 128kWh.

 

[scottf200]

Tesla website if you dive into the fine print for their gas savings price reduction.

Usable. Including buffer. So basically it is the pack size (I don’t know what total means here - they always run packs until they stop working. And Tesla doesn’t do any pack buffering to prevent actual range loss.)

Charging efficiency. Historically it has been about 0.88 or 0.89.

So maybe it is 128kWh! I just rounded to 0.9.

Thanks. I think I need some sleep. Getting close to 3am in Chicagoland.

Re: (42.9 kWh / 100) * (340 mi) * 0.9 = 131.274
I am confused what 'charging efficiency' (while charging your car from the grid) has anything to do with usage of a kWh to go a given distance?
I must be missing something simple.

I do see:
340/100 = 3.4
42.9 kWh * 3.4 = 145.86 kWh
145.86 * 90% = 131.274

 

[AlanSubie4Life]

I am confused what 'charging efficiency' (while charging your car from the grid) has anything to do with usage of a kWh to go a given distance?

When calculating gas savings, you have to include charging losses. So that is what Tesla quotes.

If you run this same basic calculation on most EVs, you’ll end up with the pack size. (Ford does not work, but try it with Rivian, Tesla (use 0.88 if you want.))

42.9kWh/100mi is wall to wheels. Those numbers in this context are always quoted as wall to wheels.

So that means it takes 146kWh to fill the pack.

So the pack is about 128kWh-131kWh.

 

[scottf200]

When calculating gas savings, you have to include charging losses. So that is what Tesla quotes.
If you run this same basic calculation on most EVs, you’ll end up with the pack size. (Ford does not work, but try it with Rivian, Tesla (use 0.88 if you want.))
42.9kWh/100mi is wall to wheels. Those numbers in this context are always quoted as wall to wheels.
So that means it takes 146kWh to fill the pack.
So the pack is about 128kWh-131kWh.

Oh gosh, when I read your first sentence it dawned on me. Plus I got some sleep! Seems obvious now. Thank you for your patience.

 

[AlanSubie4Life]

Oh gosh, when I read your first sentence it dawned on me. Plus I got some sleep! Seems obvious now. Thank you for your patience.

FWIW if you use 129kWh as the pack size (which would mean 88.4% efficiency), this means usable pack would be 123kWh (95.5%), as has been reported. (This was reported elsewhere by @gtg465x) So perhaps ~129kWh is the current best estimate for pack size.

However, range numbers are achieved with the 129kWh, so that is the number to use in your spreadsheet when calculating efficiency and comparing to other manufacturers (as long as the same definitions are being used everywhere, of course!).

 

[scottf200]

Oh gosh, when I read your first sentence it dawned on me. Plus I got some sleep! Seems obvious now. Thank you for your patience.

FYI, I've been watching videos and multiple state 123 kWh. I'm not sure how to 'reconcile' this ... which matters for the calculations.
miles/kWh *** Wh / mile *** kWh/ 100 mi

Marques Brownlee/ Title: Driving Tesla Cybertruck: Everything You Need to Know! [link to YT location below]

 

[AlanSubie4Life]

FYI, I've been watching videos and multiple state 123 kWh.

Marques Brownlee/ Title: Driving Tesla Cybertruck: Everything You Need to Know! [link to YT location below]

Yes. And that is potentially consistent with 129kWh.

I think it would be a mistake to use 123kWh to calculate efficiency numbers since that would imply very inefficient charging (84.3%).

Of course one has to be consistent across manufacturers. I think it is good to use the fueleconomy.gov numbers as a crosscheck to make sure everything is in the right ballpark (these numbers seem very wrong for the Lightning FYI).

 

[AlanSubie4Life]

which matters for the calculations.

So definitely use 42.9kWh/100miles as the starting point, which means 0.884 * 42.9kWh/100mi = 37.9kWh/100mi

Which means 379Wh/mi at CURRENT published numbers for Tesla. (Need to 1) wait for official numbers and 2) determine tires used)

If you follow this same formula for Model 3 or whatever, you’ll get the right result for capacity.

For example, Model 3 Performance:
33705Wh/Ge / 113MPGe = 298Wh/mi. (This is to get extra sig fig instead of using 30kWh/100mi.)

298Wh/mi*315mi*0.884 = 83kWh

(A little high, but pretty close to “correct” ~82kWh extracted in EPA test - I haven’t looked at the document but I recall well one version of this battery got over 82kWh out in the test). “Usable” is 77-78kWh when new but not relevant here.

There may be minor error here caused by different city/hwy weight but I don’t think so. Would have to go through all the calculations to make sure.

 

[AlanSubie4Life]

Lots of talk in videos about 1366 4680 cells, does not make sense. Am I missing something? Misheard? Not divisible properly unless I am missing something…
1366/2 =683…which is prime. Not good.

7:30 here:

Also posted on Twitter by Baglino that for 400V, pack is split in half. Must keep balance!

https://x.com/baglino/status/1730391023799386480?s=20

Background:
I don’t think anyone ever worked out the WAY underperforming 67kWh Model Y AWD 4680 pack.

Summary post: '2022 Model Y 4680 Structural Pack is "Amazing", Says Munro & Associates'
2022 Model Y 4680 Structural Pack is "Amazing", Says Munro & Associates
Apparently 92s9p, 67kWh pack capacity. Depop 1 out of 9? No one knows (pack not light enough for that?) Only 81Wh per 4680 if fully populated; terrible, or software limited. Info needed here since 81Wh is lower than expected (91Wh might be better?).

I can think of a few configurations close to 1366, but there are limitations due to bandolier structure and module structure, on what is actually possible. Have not accounted for all that below:

1376 = 2*8*86 (361V/722V (max voltages, not how they will be referred to, seems to be about 86%, so 310V/620V))
Would require 94Wh per 4680
86 not divisible by 4…no idea module count…

1344 = 2*7*96 (402V/804V aka 350V/700V) same as Model 3 voltage.
96Wh per 4680
Maybe. How would it be built though? Depopulate bandoliers?

1344 = 2*8*84

1656 - 2*9*92 - two Model Y packs using same structure. Way too big. If it had Model Y terrible density it would be close, 135kWh. But still too big.

Anyway. If anyone has seen this worked out, please post.

What is bandolier size?

 

[scottf200]

So definitely use 42.9kWh/100miles as the starting point, which means 0.884 * 42.9kWh/100mi = 37.9kWh/100mi

Which means 379Wh/mi at CURRENT published numbers for Tesla. (Need to 1) wait for official numbers and 2) determine tires used)

If you follow this same formula for Model 3 or whatever, you’ll get the right result for capacity.

For example, Model 3 Performance:
33705Wh/Ge / 113MPGe = 298Wh/mi. (This is to get extra sig fig instead of using 30kWh/100mi.)

298Wh/mi*315mi*0.884 = 83kWh

(A little high, but pretty close to “correct” ~82kWh extracted in EPA test - I haven’t looked at the document but I recall well one version of this battery got over 82kWh out in the test). “Usable” is 77-78kWh when new but not relevant here.

There may be minor error here caused by different city/hwy weight but I don’t think so. Would have to go through all the calculations to make sure.

View attachment 995537

Not ignoring your help and clarity ... just had a busy day doing some non-EV things
I'll dig back in soon.

 

[scottf200]

So definitely use 42.9kWh/100miles as the starting point, which means 0.884 * 42.9kWh/100mi = 37.9kWh/100mi
Which means 379Wh/mi at CURRENT published numbers for Tesla. (Need to 1) wait for official numbers and 2) determine tires used)
...

Really valuable help and input. Thanks a bunch. Really helps see how the Tesla number 42.9 kWh/100miles gets to 123 kWh publicized *everywhere* pencils out.
CT part of chart below. Full chart here.

 

[AlanSubie4Life]

Really valuable help and input. Thanks a bunch. Really helps see how the Tesla number 42.9 kWh/100miles gets to 123 kWh publicized *everywhere* pencils out.
CT part of chart below. Full chart here.

We’ll see if it holds up!

Would be nice to have pack details. Only have Camissa video saying 1366 cells, which is wrong, unless some of those are blank cells (since it is only 2x683 and has no further factors).