NHTSA Opened Up the Model S Battery Pack - Pics

[EarlyAdopter]

I don't think I've seen this posted anywhere here, but if you dig through the report documentation from the NHTSA crash testing of the Model S after the pole side-impact test they opened up the traction pack for examination and included photos in the report. These are the first I've seen of a wide open Model S battery pack. Note the minor denting on the driver's side middle of the pack from the impact with the pole.

 

[vfx]

OK, start countin!

 

[yobigd20]

it looks like there are some missing batteries

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hard to tell, but I see about 31 cells in each row, 14 rows per section, and 7 sections. 31x14x7=3038 batteries. Are they double stacked or am I blind?

 

[JRP3]

OK, start countin!

LOL, my first thoughts as well :biggrin:

Looks like 32 or 33 in each row to me, still not enough.

 

[aronth5]

it looks like there are some missing batteries

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hard to tell, but I see about 31 cells in each row, 14 rows per section, and 7 sections. 31x14x7=3038 batteries. Are they double stacked or am I blind?

No you are not blind just don't tell anyone but those are the new 6.2Ah top secret batteries:smile:

 

[brianman]

If you compare the first picture (figure 13) with the other 2 (figures 15*), there are two blocks of the ones that yobigd20 was counting.

Also, I count 32-33.

So figuring that...
2*32*14*7 = 6272

 

[Wattson]

In figure 15A, you can see the exposed area is just half of the pack. See the butterfly construction, there's another mirrored side. Multiply your counts by two.

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Replied at the same time. Brianman beat me to it.

 

[JRP3]

Still substantially below the 7000+ cells we've been told and have calculated are needed to build an 85kWh pack. Even if we use 33 cells per row that gives us 6468.
If that number is correct then Tesla would need to use a 3.65 ah cell to get 85kWh, assuming a 3.6 nominal voltage.

 

[PV4EV]

Still substantially below the 7000+ cells we've been told and have calculated are needed to build an 85kWh pack. Even if we use 33 cells per row that gives us 6468.
If that number is correct then Tesla would need to use a 3.65 ah cell to get 85kWh, assuming a 3.6 nominal voltage.

Looking through the NHTSA documents, one of the photos shows the car is a 60kWh. Does the smaller MS ESS have less 18650s ? Did they keep overall vehicle weight and dynamics the same using ballast of some sort ?

 

[jthompson]

Thank you, Early Adopter, for posting this! This is the kind of stuff I love to learn about my Model S!!!

 

[yobigd20]

If you compare the first picture (figure 13) with the other 2 (figures 15*), there are two blocks of the ones that yobigd20 was counting.

Also, I count 32-33.

So figuring that...
2*32*14*7 = 6272

Yes! If you look at the "empty battery" areas between the two photos they are different! Nice catch.

 

[AnOutsider]

OK, start countin!

That's what I was thinking. I'm also wondering what the damage would have been if the pole had hit at a midpoint between those support bars. A couple cells ruptured? I also wonder if, like the fixed headrests, Tesla designed those supports at the exact position for the tests.

 

[scaesare]

No pictures of the taller front "nose" of the pack. I've seen various claims about that portion of the pack: 2 more battery sheets stacked atop each other, a reservoir for the battery coolant, or the active electronics module for the pack.

They indeed mention 14 battery sections "sheets" within the pack, and that it's a 60KWh pack... so I wonder if they missed 2 up front, or if that's correct.

 

[jthompson]

Page A-7 of the Indicant Test report shows the 60kWh sticker.

 

[JRP3]

They indeed mention 14 battery sections "sheets" within the pack, and that it's a 60KWh pack... so I wonder if they missed 2 up front, or if that's correct.

I've never thought that was correct.

 

[stopcrazypp]

I've never thought that was correct.

The information I have so far shows evidence of 16 modules for the 85kWh and likely 14 modules for the 60kWh.

We know from the diagnosis screen that the 85kWh pack has 16 modules with 6 groups in series (so 96 groups in series):
https://lh5.googleusercontent.com/-...AAAATUE/Ngjz-jlZMYc/w702-h498-no/IMG_0876.JPG

We know the pack is structured with 14 modules in the flat section and 2 modules stacked in the front where the coolant connectors are:
http://www.teslamotorsclub.com/showthread.php/16535-Battery-facts?p=333846&viewfull=1#post333846

Charging voltage shows evidence of there being 14 modules (or equivalent) in the 60kWh pack:
60kWh 352V (14 modules in series *6 series group per module*4.19V)
85kWh 402V (16 modules in series *6 series group per module*4.19V)
http://www.teslamotorsclub.com/show...-and-P85/page3?p=445256&viewfull=1#post445256

The NHTSA test data (page 6) seems to match this for the 60kWh pack:

Minimum Operating Voltage 210
Maximum Operating Voltage 350

The propulsion battery encompasses fourteen (14) battery modules, each of which
consists of six (6) cells

We had a previous guess of 7104 cells for the 85kWh (16*6*74), 14 modules for 60kWh means 6216 cells (14*6*74).

Of course, the capacity math (85 vs 60) does not really work out using 16 and 14 modules, so that's the weird bit (maybe different capacity cells)

 

[JRP3]

Interesting, somehow I missed that graphic showing the front modules.

 

[rrosenbl]

How did you get into that diagnostic mode screen? I'd like to snoop around behind the curtain while waiting to charge or if bored...

 

[vfx]

At the original Tesla Factory opening an engineer told me there were batteries in the upper section "because they had room".

Later JB said they could make a 500 mile car but they had to stop somewhere. I assume weight diminishing returns on that.

 

[scaesare]

stopcrazypp-

Yeah, that's the graphic I remember and the discussion of the two additional sheets in the pack "nose".

i wonder if that space is simply empty in the 60KWh pack then... probably so.

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Later JB said they could make a 500 mile car but they had to stop somewhere. I assume weight diminishing returns on that.

Yeah.. that and cost.