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Discussion Starter · #1 ·
Those ultium packs have a completely wireless BMS in them, meaning all the modules have a BMS slave with a 2.4ghz connection to a master unit which does all the calculations.


I assumed this was all super proprietary stuff and we wouldn't be able to touch it till Hummer EVs star crashing but now I'm not so sure....

It seems Ti has.... something? It keeps coming up in videos of theirs and they have a demo unit. I'm guessing they don't sell to consumers, although there's a dev kit supposedly? Interesting stuff


Sure as hell would simplify packaging, this makes splitting packs a lot more feasible and battery boxes don't need to size for wire looms all over
 

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I noticed that one from TI as well and am thinking about using it if I can ever get my battery config and layout to settle down. I believe it's a catalog part

All the fanboys gloat about Tesla's battery management tech...I believe that also came from TI.

So, no...not ghetto.

Problem is RF can't get through a metal module case, so need to work around that. Not difficult, but nothing is free.
 

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The entire system is inside a faraday cage - the metal battery box. It's also very near field, meaning next to no power on the transmit side.

The passives component count, though, seems huge, so it's not exactly a slam dunk and most of the wiring is still there inside the module afaik.
 

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Discussion Starter · #7 ·
I would also be skeptical of the hurdles if this wasn't like, a major calling card of GM's new battery architecture they're going to be using for the next N years, and Ti didn't have a product they're showing off. So presumably the more obvious problems like internal radio reflectance are solved, at least I hope.

But yes this would all be inside the battery box, with the master unit being the only wired thing on the outside (likely sitting on the CANbus)

I'm actually down to try out this Ti dev kit BUT I'm not sure if it's an all on one locked BMS, or if it's just a data relay and you need a proper BMS doing the thinking (like an Orion)
 

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I don't know what drove GM to this level of complication to avoid some wire length... perhaps isolation issues within the pack with their battery voltage of up to 800 V while charging?
 

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Dumb question: How do these balance cells? Do the individual boards drain individually? Otherwise pretty brilliant actually. Short range wireless is easy as heck and low power, and for the manufacturers, saving assembly time is probably a big draw.
 

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Discussion Starter · #13 ·
Standardization and reduction of manufacture. You'd be shocked how much a lot of BMS wires cost in terms of production when you're at hyper mega massive scale. Not just the wire raw cost but the cost of making all those looms and the time cost of installing and running and plugging in all those connectors on the factory floor

Wireless also likes you standardize like crazy. Got 6 modules instead of 12?
With wiring, uh oh! Time to redesign your harness and make a new part number, change your manufacturing flow a little which means slightly different training for people on the line etc etc.
With wireless bms? Ok, change a line in the BMS master configurator, you just stamp out Ultium modules like nuts and literally don't care where they end up in.

basically all that annoying shit in an EV conversion? annoying shit at 20k cars a year is a lot of wasted money and time

Logistics, baby!
 

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Dumb question: How do these balance cells? Do the individual boards drain individually?
Presumably yes. Although more sophisticated systems are possible, it appears that BMS balancing is normally based on discharging individual cells through bypass resistors, so there's no need for current to flow between the cell and a central BMS device. It is common for modules to be equipped with "slave" BMS units which handle this themselves, only using their connections to the BMS master for coordinating communication; that makes a wireless network a straightforward (although unnecessary) variation on the usual wired network between BMS master and slaves.
 

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Dumb question: How do these balance cells? Do the individual boards drain individually? Otherwise pretty brilliant actually. Short range wireless is easy as heck and low power, and for the manufacturers, saving assembly time is probably a big draw.
This is how most OEM modules work. The balancing circuitry is attached to each module, and a main BMS controller of sorts communicates with this circuitry. Helps reduce wiring complexity and points of failure.
 

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With wireless bms? Ok, change a line in the BMS master configurator, you just stamp out Ultium modules like nuts and literally don't care where they end up in.
That part about the module is true whether the module's BMS slave is wired or wireless. Arguably wireless is worse for module complexity, because each module must be configured to a specific position in the system (by a configuration switch or setup process), rather than just plugged into a BMS master port which implies the position. But it's a minor detail either way.
 

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Yes. We used to lurk in these kinds of user ghettos for ideas and perspective, though a video takes a few weeks to get produced and signed off so not in this case.

I almost got fired for producing one of the first app videos in the semiconductor industry to go on a website. Group-hug company never did anything first, lol. I also worked for a company mentioned in this thread for a bit 🤓
 
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