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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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Wireshark! That's hilarious.

 

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At any rate, if I were a manufacturer, you just have a slot on your assembly line attaching the BMS slave modules to batteries out of a bucket of preconfigured ones with the node number on them, slap a sticker with the module #, and send it down to be dropped into the pack. This would save oodles of time.

Edit: scratch that, just label the preconfigured bms slaves and attach them to a pack with the modules already in them. Still...

Now they just need to invent wireless bus bars.

 

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My thoughts exactly. What do you gain from wireless? There's really not a lot of wires in a BMS master-slave network, not sure what GM is on about. This seems to be more of a "use big technological words to impress customer" type video.

No I think you missed the point entirely. There is no need for current flow between the cell and a central BMS. You only need the coordinating BMS master to tell something at the cells to discharge, and read the voltage at the cell itself. How that communication occurs (as long as it's reliable) is irrelevant. So what you gain from wireless is a gain of some amount of time saved assembling the battery if you're making 20 thousand vehicles, and X modules * Y cars * Z length of copper wiring which ain't nothing for a company which for which cost optimizing is a way of life. For the DIYers it may be a couple dozen bucks, but multiplied times all the vehicles and multiplied times the other areas they are engineering to save a few adds up real quick.

For us DIYers it'd be pure convenience in wiring, again, if reliable and not complicated for us to interface to. Personally, given my experience in the rest of my career, I'll trade money for wires but that's not to say this is a bad idea. I think it's a great one for the industry.

 

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No, we are on the same page. I'm familiar with how it works in most OEM vehicles currently. Obviously wireless cell taps would be very much impossible (wireless electricity)! I just don't think there would really be any cost savings. 22awg wires for CAN communication with balance boards is a cheap and simple solution. Wireless is not as simple, and I can't imagine it's as cheap (although I'm not sure).

I need to learn more about it though for sure.

Most definitely cheaper. 22awg is cheap, sure, but a battery pack is ~4x5 ft? Just guessing, but if you have say and I'm just doing back of the napkin here, 96 cells, then you still have to run 1 22awg wire between each cell tap and a perfectly centered BMS about 32in, with copper 22awg copper at 514 ft/lb means about 2lb of copper, at 4.3$ a lb at the time of this post, so ~$9 of copper before you price in the creation of the small wiring, sheathing, and upcharge for creating the wiring. Then add the cost of connectors per module, tacking on per supplier profits, etc, and again, adding up. Then the connectors on the BMS master and the many many additional traces on the PCB and overall size increase that result.

The components on the PCB, even looking at it, are a handful of surface mount components and a small cheap IC. The wireless bits are cheap too. And no long distance high cost copper wiring. My guess is that even in material cost they're 2x ahead of a wired BMS setup at scale.

But this is all back of the napkin material cost. The real cost is that they're saving some fraction of human time on an assembly line. Each of these connections to each battery module takes time * wage cost, plus perhaps quality control, which I'm guessing is at or above the material cost.

 

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reckoning for the just in time manufacturing model

Bingo. JIT only works when everything is running smoothly and demand is predictable. The last couple of years have been the exact opposite.

Edit: it also boggles my mind to think about how many steps there are for any given product, including electronic components. And a fault in any one of them piles up like an icy Florida highway.