Tesla BMS

[circuit]

Anyone seen it? Zero info on the internetz... As if it does not exist.

 

[Teh Stork]

Second this.

I do think it is because many BMS patents are probably being infringed upon by Tesla - so by not sharing that they use some techniques, they will probably get away with it. I happen to know this since I've got a BMS idea that is patentable, and Innovation Norway funded the prestudy for this patent. (I'd like to add that I find patents frustrating). The number of patents on batteries are quite astounding.

I know that the Tesla battery sub-modules are outfitted with a microprocessor that samples voltage and temperature, but if this voltage is cell-level or module-level? I don't know. Speculation around the web quickly degrades into BMS/no-BMS and Series/parallell discussions.

 

[Dauntless]

Anyone seen it? Zero info on the internetz... As if it does not exist.

Literally, no, there's a lot of info. Maybe not the info you're after. What ARE you after?

http://www.freepatentsonline.com/8536825.pdf

The Roadster has 99 cells in series which means that the BMS monitors 99 individual voltages, no matter how many cells are in parallel.

We know that each cell is individually fused. My thought, from what I've read, is that they can't turn off a single cell but they can turn off a small group of cells (way less than a sheet).

. . . .they balance to the "brick" level, each of which has 69 18650 cells. 9 of these bricks are rolled up into a "sheet", of which there are 11.

In this configuration each "brick" has 69 cells wired in parallel. Voltage range of each brick ~3.0-4.1V.
9 bricks are then wired into series to form a sheet. Voltage range each sheet is ~27.0-36.9V.
11 sheets are then wired into series to form a pack. Voltage range each pack is ~297-406V.

The 85 kWh Model S probably has more cells in each brick. The 60 kWh Model S appears to have a lower voltage by looking at 60 kWh pack SuperCharger voltage reports - I'd bet they use fewer sheets than the 85 kWh Model S.

 

[circuit]

That is great, I have not seen that patent earlier.
But I am more interested in actual BMS on schemotechnical level, I mean how it is arranged and connected to cells, if it is split up in groups with common communication line, what kind of balancing and at what current it is running, etc... A picture of whole thing would be very nice, and a hi-res picture of actual PCB would be super.