Wanted: Information about Tesla Pack Modules

[MitchJi]

Hi,

Since they are either available now or will be available soon, from wrecking yards, I'd like to find out more about them.

This is all I could turn up on web, not even the capacity numbers match (85 / 16 = 5.3).

The 85 kW·h battery pack contains 7,104 lithium-ion battery cells in 16 modules wired in series (14 in the flat section with two additional modules stacked on the front). Each module contains six groups of 74 cells wired in parallel; the six groups are then wired in series within the module.

http://www.plugincars.com/all-family-tesla-battery-packs-solarcity-backup-systems-129025.html

The company, which specializes in solar leasing, is headed by Elon Musk’s cousin, Lyndon Rive, and it was Musk—also the company’s chairman and major investor—who first suggested that Rive and his brother, Peter (now the chief technology officer), get into solar.

So who’s surprised that SolarCity’s new “smart energy storage system” combines photovoltaics with Tesla battery packs? “It’s the exact same battery pack,” CEO Lyndon Rive told me. “The Tesla pack is modular in 10-kilowatt-hour buckets, so we can make it any size we want.”...

For now, a small 8-kWh wall-mounted Tesla energy storage unit is offered with a 10-year warranty.

Questions: Voltage and ah, weight and dimensions. Structure. BMS (is it built into the individual modules?). Electrical connections etc....?

In other words are the modules usable, or are they best used as groups of parallel, or :cringe: individual 18650 cells?

 

[Hillhater]

Have you seen the "S" pack internals ?..
http://www.teslamotorsclub.com/showthread.php/21850-NHTSA-Opened-Up-the-Model-S-Battery-Pack-Pics

There is much debate over exactly how many 18650's there are in a pack, but most agree they are arranged as 68p and 98s

....You can see that it is in 2 halves, each half has 7 little bays, each bay has 7 rows of cells, and each row (this is where the counting gets tricky) seems to have 68 cells each.
2x7x7x68=6,664 cells.

http://www.teslamotorsclub.com/showthread.php/17590-Model-S-Battery-Pack-Cost-Per-kWh-Estimate/page49

So nominal voltage would appear to be 98 x 3.6v =353 volts ( full capacity of 98x 4.2v ? = 411volts ?)
Capacity is reported at 85kWhr for the bigger pack, which would suggest that the cells are around 3.4 Ahr each.?

 

[Hillhater]

Just to add to the confusion !...
take a detailed look at this Tesla patent. It is for the Ballistic shield for the pack, but it does describe in detail the make up of the cell modules in a " preferred embodiment" layout.
https://www.google.com/patents/US8393427?dq=Battery+++inassignee:%22Tesla+Motors,+Inc.%22&hl=en&sa=X&ei=mSLUUpzIJ4zU4wTl8oHgDA&ved=0CGgQ6wEwBzgK
Inbrief , it states that there are 16 modules, each containing 370 individual cells, for a total of 5920 cells.
Most likely the 60 kWhr pack. ?
It still shows each module has 7 strings of parallel cells, implying a 112S ( 403volt) configuration ?
BUT, the 370 cell count in a 7s module doesnt give an even number of cells in each string ??
Note: .. it has been stated else ware that there are "blank" sections in some modules.

So , i would suggest that there are more than one configuration of these "Model S" packs, with different numbers of cells in some modules, and possibly even different number of modules in some packs !

Weight.??
According to this review, the 85kWhr pack weight is 1323lbs (600kg)...
http://www.caranddriver.com/reviews/2013-tesla-model-s-test-review

 

[MitchJi]

Hi,

Have you seen the "S" pack internals ?..

There is much debate over exactly how many 18650's there are in a pack, but most agree they are arranged as 68p and 98s

....You can see that it is in 2 halves, each half has 7 little bays, each bay has 7 rows of cells, and each row (this is where the counting gets tricky) seems to have 68 cells each.

No I didn't. Thanks for posting the photo's and the link to the discussion thread! Maybe you can remove the picture since these copies are formatted better (the orininals don't display well in firefox)?


I am more interested in the "modules" than the total pack (Leaf modules are more useful to many of us than the entire pack). It looks to me like seven "modules" (sections separated by dividers), with 7 strings of about 32 or 33 cells. Someone speculated that the strings have two layers so each string has 64-66 cells. That is the only way I can think of that the pack totals for the number of cells and ah come close to being 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):

But we can see 7 strings of parallel cells in each module in the pictures.

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:

Charging voltage shows evidence of there being 14 modules (or equivalent) in the 60kWh pack:
60kWh 352.8V (14 modules in series *7 series group per module*3.6V)
85kWh 403.2V (16 modules in series *7 series group per module*3.6V)

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.

Page A-7 of the Indicant Test report shows the 60kWh sticker [for the pictured pack].

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.

Weight.??
According to this review, the 85kWhr pack weight is 1323lbs (600kg)...
http://www.caranddriver.com/reviews/2013-tesla-model-s-test-review

That means each module weighs about 83 lbs 1323 lbs / 16.

And I think each module is about 726mm (29in) long (32-33 cells x 20-22mm {18mm plus some space for cooling etc.}), and the width is about 154mm (6in) (7 x 20-22mm).

The nominal voltage is 7 x 3.6 = 25.2 and the ah is roughly 64 x 3ah (not sure of the exact ah of the Tesla cells but 3 is probably close) 192ah. It might be relatively easy to divide the strings in the middle for a 50.4v 96ah module.

So 25.2V x 192ah = 4,838 wh.

I think it's a safe assumption that it would be fairly easy to remove the modules intact from the pack since they would not assemble them in place.

 

[MitchJi]

Hi,

More information:
http://www.teslamotorsclub.com/showthread.php/13121-Inside-the-Tesla-battery-pack

Here's some Tesla battery "secret sauce" for your enjoyment:

Here you can see the bare 18650 laptop cells. They are interwoven with an aluminum channel (golden color) that carries coolant to each cell. Looks to me like a good 25% of each cell is in contact with this. (via way of a thermal pad and kapton electrical insulator)

This is the top of a module, each cell is connected to it's buss via a tiny single wire, which helps distribute current and acts like a fuse in the event of a cell fault.

How is the plate the wire connects to held against the cell? If someone copied ( :wink: err reverse engineered) those pieces they could corner the market on solderless 18650 cell holders.

It might not be too hard to separate those and easily build solderless packs with the exact number of parallel cells and the exact number of series strings you want.

 

[fechter]

There doesn't seem to be much information available on these. Maybe because it's a $85,000 car and it has one of these:

Wooses. I know Tesla is pretty good about taking care of any battery issues under warranty so not many folks have had a reason to crack one open.

 

[Hillhater]

The individual cell connect wire is ultrasonic ly welded to the cell cap.
Please be aware also that the pictures you have showing the close up of the cooling tubes and cell connects, are from the pack for a Toyota ERav4 which uses a different tesla built pack configuration.
As I mentioned, there is much conjecture as to the precise configuration of each of these different Tesla packs...
96 , 98, or 114 in series ?
63, 66, 68, 69, ...in each parallel string ?
14, 16, modules ?
Some strings and modules are even said to have blank sections in them ?
And we certainly know that tesla have used different capacity cells from several different suppliers at times.