Tesla's 85 kWh rating needs an asterisk (up to 81 kWh, with up to ~77 kWh usable)

[Cottonwood]

At full draw on a non-ludicrous 85 you are only drawing ~0.2A per cell. (And even in your hypothetical situation does it actually draw 1,300A continuously?)

So I doubt that it makes a significant difference in the amount of power you get out of the cells.

Right, the pack is in 96 parallel 74 series configuration. You divide total amperage by 74 to get individual cell numbers.

Almost correct @stopcrazypp. The configuration is 74 parallel, 96 series in an 85. As you correctly state, the car's total battery current gets divided by 74 to get the per cell current. To complete the puzzle, you divide the total pack Voltage by 96 to get the per cell Voltage.

That means that discharging towards the end of a "Launch" at 400 Volts and 1300 Amps gives per cell numbers of 400 Volts / 96 cells = 4.17 Volts per cell and 1,300 Amps / 74 cells = 17.6 Amps per cell. Charging at 360 Volts and 333 Amps gives 3.75 Volts per cell and 4.5 Amps per cell at the approximate maximum Supercharger charge power of 120 kW.

 

[OddB]

That is exactly the problem people have been having with this numbers. This is a ~1 year old car with 14048km (8729 miles, ~40-50 cycles) of wear on it. Under the same wear, NCR18650B cells would lose 5.8% of its capacity (unfortunately there is no official datasheet for NCR18650BE). That doesn't tell you what is reported for a car right off the assembly line, much less a pack or cell off the assembly line (before supposed QC related cycling and aging). If you back calculate with 5.8% loss, it would indicate a brand new pack (with cells not QC cycled by Tesla) would get 82.1 kWh + 4kWh = 86.1 kWh.

Also the "4kWh" (it should be 4kWh, not 4kW) is also never measured and not possible to measure inside a car.

Is there a difference in the size of the bricking protection when using Range Mode ? When you switch it on and off it looks like you gain almost 1 kWh....

 

[kennybobby]

...That means that discharging towards the end of a "Launch" at 400 Volts and 1300 Amps gives per cell numbers of 400 Volts / 96 cells = 4.17 Volts per cell and 1,300 Amps / 74 cells = 17.6 Amps per cell.

Except the pack voltage gets pulled down below 300 volts during a launch.

 

[stopcrazypp]

Almost correct @stopcrazypp. The configuration is 74 parallel, 96 series in an 85.

Good catch on that. I flipped parallel and series. Too bad edit time passed.

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Is there a difference in the size of the bricking protection when using Range Mode ? When you switch it on and off it looks like you gain almost 1 kWh....

No idea, that would be for the people with CAN bus access to answer. However, my point was there is no way to verify the brick protection capacity inside the car without modifications because the car won't let you access that (while the Roadster did).

 

[glhs272]

But I suspect that the car report numbers right at, or maybe above, rated capacity on the 60s and 70s. The fact is that Tesla uses a different rating calculation between models, which misleads people on what they are actually getting.

I wish somebody with a 60, 70, and 90 would get together with someone with a CAN logger so we could get some actual numbers.

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At full draw on a non-ludicrous 85 you are only drawing ~0.2A per cell. (And even in your hypothetical situation does it actually draw 1,300A continuously?)

So I doubt that it makes a significant difference in the amount of power you get out of the cells.

I ordered a CAN logger from EVTV. I have a 60. What info would be helpful to the community that we don't already know about the 60 pack?

 

[MP3Mike]

I ordered a CAN logger from EVTV. I have a 60. What info would be helpful to the community that we don't already know about the 60 pack?

I don't think we have seen any of the numbers yet: brick protection amount, usable kWh, or full pack kWh.

 

[glhs272]

I don't think we have seen any of the numbers yet: brick protection amount, usable kWh, or full pack kWh.

OK. I will see if I can get some info in this weekend.

 

[Pajda]

OK. I will see if I can get some info in this weekend.

It would be great if you can find this data for 60kWh pack: :smile:

View attachment 111297

 

[jpet]

I don't think we have seen any of the numbers yet: brick protection amount, usable kWh, or full pack kWh.

smac posted them when he received his logger 2 weeks ago:
Let the hacking begin... (Model S parts on the bench) - Page 84

A 60 kWh battery has 59.8 kWh available and an energy buffer of 2.8 kWh so the full pack is 62.6 kWh.

 

[FlatSix911]

One only needs to look at the front page to see which car is over/underrated.
All the info needed is and was there from day one.
Current situation:
- 70D: 240 epa miles for $76.200 : $317.50/mile
- 90D: 288 epa miles for $89.200 : $309.72/mile

90D is a better value (or under-rated) compared with 70D and vice-versa.

Incomplete data ... here is the full story:

- 70: 230 epa miles for $71.200 : $309.5/mile
- P90D: 270 epa miles for $109.200 : $404.4/mile
- P90D: 270 epa miles for $119.200 : $441.4/mile

Who cares. Buy a different car if you're bothered.

What difference does it make? The truth will set you free...

I understand that Tesla tries to present their cars in the best possible way by using the highest specs available.

Since this is a battery capacity centered thread, let's take a look at the specs for the Sanyo NCR18650GA cell.
This is the cell that is allegedly being used as the basis for the custom version of the Tesla cell in the "90 kWh" battery.

The NCR18650GA is being marketed as a 3500 mAh cell (see the title on the webpage).
3.5 Ah x 3.6V x 7104 = 89.510 kWh

The minimum capacity of this cell is 3350 mAh and the typical capacity is 3450 mAh.
Now let's take a look the the detailed spec sheet from Sanyo (Panasonic).
On page 7 of this document, you'll be able to find the rated capacity of 3300 mAh.

So here we are, 1 cell and 4 numbers...
Want to know the real capacity an owner of a 90D or P90D will be able to experience?
Let me take an educated guess: 3.3 Ah x 3.6V x 7104 = 84.396 kWh with 80.396 kWh available for driving after removing the 4 kWh energy buffer (brick protection).
My take is that Tesla's specs are OK but, as wk057 indicates, they should come with an asterisk indicating typical usable capacity when new.

smac posted them when he received his logger 2 weeks ago:
Let the hacking begin... (Model S parts on the bench) - Page 84
A 60 kWh battery has 59.8 kWh available and an energy buffer of 2.8 kWh so the full pack is 62.6 kWh.

So your calculations show the 90D has a 84.4kWh battery and the 60 has a 62.6 kWh?

 

[jpet]

So your calculations show the 90D has a 84.4kWh battery and the 60 has a 62.6 kWh?

For the 60 the number is based on the CAN bus so those are the "calculations" from Tesla. :wink:
We yet have to find a 70 and a 90 to get the CAN data from but I already got my educated guess for the 90 confirmed by an owner.

 

[stopcrazypp]

For the 60 the number is based on the CAN bus so those are the "calculations" from Tesla. :wink:
We yet have to find a 70 and a 90 to get the CAN data from but I already got my educated guess for the 90 confirmed by an owner.

The CAN never reports a composite capacity number, so those are calculations done by the user based on assumptions of what those fields mean.

 

[jpet]

The CAN never reports a composite capacity number, so those are calculations done by the user based on assumptions of what those fields mean.

Fine, if calculations bother you, let's stick with 77.6 kWh as the reported available capacity for a typical 85 kWh pack and 59.8 kWh for a typical 60 kWh pack.

As more and more cars get CAN logged we will see how much variance there is in these figures. I hope to get my car back from the body shop this week so that I can finally start using my CAN logger as well. I want to research if the BMS_nominalFullPackEnergy number changes over time after e.g. balancing or re-calibrating the BMS.

 

[pupik]

Fine, if calculations bother you, let's stick with 77.6 kWh as the reported available capacity for a typical 85 kWh pack and 59.8 kWh for a typical 60 kWh pack.

As more and more cars get CAN logged we will see how much variance there is in these figures. I hope to get my car back from the body shop this week so that I can finally start using my CAN logger as well. I want to research if the BMS_nominalFullPackEnergy number changes over time after e.g. balancing or re-calibrating the BMS.

58.9kWh for 60kWh pack
look here :wink:

 

[jpet]

58.9kWh for 60kWh pack
look here :wink:

Peer review is good. Thanks pupik!

 

[pupik]

Here is a graphic illustration, how great it works BMS. Some time ago I tested discharging for SOC < 0% and I small tortured my battery pack... :wink:
Attention!!! Do not try... "Tow Mode Unavailable" It is standard for this state
mirror story here my result same / small difference -> my 12V battery was fit 13.9V :smile:

SOC 0% + drive 5-10miles (3-4kWh) = "Car Shutting Down" = "Game Over" = "Tesla is Brick"
current 0A main battery

SOC 100% charge 22kW (charging off on 98%)

 

[kennybobby]

It looks like CELL or brick #54 is just under 2.9 at 0%--i wonder if that is the low voltage fault setting in the main BMS?

Didn't you drive further and use up the 4kW anti-bricking reserve--How did you override the anti-brick to allow further driving?

And so your pack is fine after the torture test--and no cells hold at 4.2 for 100% soc?

 

[jpet]

It looks like CELL or brick #54 is just under 2.9 at 0%--i wonder if that is the low voltage fault setting in the main BMS?

Didn't you drive further and use up the 4kW anti-bricking reserve--How did you override the anti-brick to allow further driving?

And so your pack is fine after the torture test--and no cells hold at 4.2 for 100% soc?

Do you happen to have the last frame of the SuC log on lolachampcar's car?
If I'm not mistaken we did not see exactly 4.2V there either.

 

[kennybobby]

Do you happen to have the last frame of the SuC log on lolachampcar's car?
If I'm not mistaken we did not see exactly 4.2V there either.

Howdy Jan, yes you are correct.

 

[stopcrazypp]

It looks like CELL or brick #54 is just under 2.9 at 0%--i wonder if that is the low voltage fault setting in the main BMS?

Didn't you drive further and use up the 4kW anti-bricking reserve--How did you override the anti-brick to allow further driving?

And so your pack is fine after the torture test--and no cells hold at 4.2 for 100% soc?

If that graph is representative of the numbers after the "torture test," then the pack has never reached true zero (looks like lowest was about 2.9V). Doesn't the BMS disconnect the pack when it reaches brick protection (so you only have 12V from the lead acid battery)?

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Do you happen to have the last frame of the SuC log on lolachampcar's car?
If I'm not mistaken we did not see exactly 4.2V there either.

I presume this is because the trickle charge portion is not fully done. If it is on the slower home charger perhaps it will reach full 4.2V.

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58.9kWh for 60kWh pack
look here :wink:

Peer review is good. Thanks pupik!

This kind of mistake is why I say these are not calculations from Tesla (and this doesn't even involve the anti-brick section yet).

And from that thread, it seems the latest number in less than 2 weeks dropped to 58.1 kWh. That is a 1.4% variance from the 58.9 kWh number. Once again, when we are hand-wringing over a 5% discrepancy, finding out what causes those variances is very important (temperature, charging, discharging, software update, bugs, etc), so that you know if you are really measuring the max capacity of the pack.