On 9/24/2020 9:49 AM, moskowitz via EV wrote:
https://www.designnews.com/automotive-engineering/general-motors-slashes-battery-wiring-90-percent
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General Motors Slashes Battery Wiring by 90 Percent
[Dan Carney](https://www.designnews.com/author/Dan-Carney)| Sep 10, 2020
As[General Motors
Co](https://www.designnews.com/electronics-test/general-motors-sees-future-zero-crashes-zero-emissions-zero-congestion).
gets closer to the[production launch of electric
vehicles](https://www.designnews.com/automotive-engineering/cadillac-lyriq-reveals-new-details-gms-ultium-battery-technology)employing
the company’s[next-generation Ultium
batteries](https://www.designnews.com/automotive-engineering/cadillac-lyriq-reveals-new-details-gms-ultium-battery-technology),
it is revealing additional technical details about these upcoming batteries.
The latest revelation is GM’s partnership with Analog Devices, Inc., to
incorporate a wireless battery management system into the Ultium battery packs.
This solution not only eliminates 90 percent of the wiring in the packs, it
also provides for increased efficiency and flexibility of those packs.
Additionally, because eliminating wires in packs leaves more space inside for
additional cells, it can create additional driving range. An important factor
is that not only does the wiring occupy space, but its installation and
connection is a manual process, and there has to be space provided for workers
to do the installation, pointed out Analog Devices technical director for
automotive, Gina Aquilano. “Thereis manual assembly where you have to leave
room for someone to go in and make the connections,” she said.
The ability to install additional cells in the same size battery pack is an
example of “a tangible outcome for the end-user,” of the use of wireless
management technology, Aquilano continued.
Range also benefits because the wireless management system can better optimize
the usage of individual cells, which also increases driving range. “Your pack
is only as good as your weakest battery,” she observed. “This allows testing
cells in more of an automated way for better matching.”
This monitoring is done by more accurate sensors, which not only aids in
managing Ultium’s Nickel-Cobalt-Manganese-Aluminum cells but will provide the
precision necessary for the future, even more, finicky chemistries such as
lithium iron phosphate, Aquilano added. “Having the sensors you need for more
sustainable battery chemistries is important,” she said.
As GM has described previously, having the intelligence built into each pack
means that not only can future chemistries be managed using this same
technology, but that those future packs will be backward compatible with
today’s technology. That will let Ultium-powered EVs swap in more advanced
batteries later if they need a battery replacement at some time in their lives.
This modularity lets the packs be connected in series or parallel, in whatever
number the application requires, from six to twenty-four packs, explained GM’s
director for global battery cells and electrification, Tim Grewe. “That’s what
this wireless tech enables,” he said. “You can do any voltage or parallel
combination you want to do. There is no practical limitation on how many you
can put in series or parallel.”
The elimination of wiring from the management circuitry has another advantage:
it isn’t subject to wiring failures. “One of the huge benefits is the fault
management,” Grew explained. “On wired systems, a hard short is a big problem.
A wireless system will reconfigure so it gets information from the unaffected
nodes in the pack.”
But doesn’t wired communication provide resistance to electromagnetic
interference? “There’s a lot of [electromagnetic] noise out there,” Grewe
acknowledged. “It jumps over to a frequency that doesn’t have the noise.”
When Analog Devices proposed its wireless technology as a potential solution
for GM, “we were very inquisitive about those same questions,” he recalled.
“The nature of it is that you can switch frequencies,” Grewe said. “It provides
avoidance capabilities that were surprising to me. It will just jump to a
channel where the interference doesn’t exist.”
Just as importantly, the system documents its adjustments, providing engineers
a better understanding of the system’s performance. “It also gives you the
reports along the way to say what happened,” he said. “It has really got a lot
of capabilities that are fully validated per GM standards.”
It was these capabilities in its SmartMesh IP wireless network products for
industrial applications that led Analog Devices to mull steering the technology
into battery management for vehicles, according to Aquilano. “It has five nines
(99.999 percent) reliability, so they were very interested in applying this to
the battery pack,” she recalled.