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Discussion Starter #1 (Edited by Moderator)
There is a new YouTube video discussing GM's new battery pack plan and universal platform for their next generation of all-electric vehicles. It's actually fairly informative and touts the advantages of a new wireless battery management system.
https://youtu.be/rEyS47PyXEU

 

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Thanks, some new and interesting Ultium battery details.
 

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wireless battery technology, that's a new one, would make for a safer battery, not having wires from each cell to the battery management system.
makes me wonder what will happen when someone installs a ham radio and starts transmitting at 1 kw of power into a non matched antenna
CQ...……..CQ, can you hear me now
 

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My guess is a few integrated circuits for regulation and communication are imbedded in the pack. Maybe sort of a micro wifi network, which already has security and parity.
 

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Standardized packs among all vehicles, fewer wires, less battery weight, easier swapping of bad packs, being able to mix in newer battery packs of different chemistry all seem pretty cool assuming the wireless chips are reliable.

Sounds like GM also has million mile prototypes in the lab.
 

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wireless battery technology, that's a new one, would make for a safer battery, not having wires from each cell to the battery management system.
makes me wonder what will happen when someone installs a ham radio and starts transmitting at 1 kw of power into a non matched antenna
CQ...……..CQ, can you hear me now
There are enough electronics and networking in cars now that it's already likely a challenge to have a Kilowatt transmitter in a vehicle. Likely something fails in the power amplifier fails if the impedance matching isn't reasonable.

I'm guessing there aren't too many mobile ham rigs running a kilowatt.
 

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wireless battery technology, that's a new one, would make for a safer battery, not having wires from each cell to the battery management system.
makes me wonder what will happen when someone installs a ham radio and starts transmitting at 1 kw of power into a non matched antenna
CQ...……..CQ, can you hear me now
With SAW filters and Bluetooth likely frequency range only VHF/UHF transceivers would potentially cause problems. The ham radio would have to be really dirty to generate enough IM or harmonics to cause problems. The pack radios would also be very close to each other inside the battery enclosure and the 3rd order intercept point of the receiver portion could be designed high.
Jack Rickard and Colin are using Bluetooth in their designs with success. Sounds like a great idea to me.
Just don't use Bluetooth for (really) high quality audio transfer...it sux.
 

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As I understand it, if a transmitter isn't properly matched to an antenna a portion of the transmitted power is reflected back into the transmitter and creates unwanted heat, which could start a fire. So if the transmitter was part of a battery module, could it cause the entire battery to go up in flames?

I took the "wireless" communications in the video to mean something like Bluetooth which transmits at very low RF levels, around 2.4 mw which is is really low power. I would also expect the transmissions to be short digital bursts so the duty cycle would lower the average power even more. I don't know but my guess is the battery management hardware polls the modules one at a time, they then respond one at a time with a brief status message. So the battery modules would transmit very little of the time and at power levels that are very low. For example if it takes 3 minutes to heat a bowl of soup in a 1000 watt microwave oven, it would take a Bluetooth transmitter over 2 years of continuous transmission to generate the same amount of power, and that doesn't take into account the duty cycle. So I think the danger of fire from RF transmissions if something like Bluetooth is used is very low.

Using a wireless architecture for battery management sounds like a good idea, we'll just have to see how it works out.
 

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so, everyone is saying, not to up date modules wireless, should be done connected
but lets control the whole battery management system that way
a bit ironic, I say
 

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As I understand it, if a transmitter isn't properly matched to an antenna a portion of the transmitted power is reflected back into the transmitter and creates unwanted heat, which could start a fire. So if the transmitter was part of a battery module, could it cause the entire battery to go up in flames?

I took the "wireless" communications in the video to mean something like Bluetooth which transmits at very low RF levels, around 2.4 mw which is is really low power. I would also expect the transmissions to be short digital bursts so the duty cycle would lower the average power even more. I don't know but my guess is the battery management hardware polls the modules one at a time, they then respond one at a time with a brief status message. So the battery modules would transmit very little of the time and at power levels that are very low. For example if it takes 3 minutes to heat a bowl of soup in a 1000 watt microwave oven, it would take a Bluetooth transmitter over 2 years of continuous transmission to generate the same amount of power, and that doesn't take into account the duty cycle. So I think the danger of fire from RF transmissions if something like Bluetooth is used is very low.

Using a wireless architecture for battery management sounds like a good idea, we'll just have to see how it works out.
The heat issue and stray rf,etc. is with the 1 Kw ham transmitter. I concur the wireless battery communication is likely in the milliwatt range and not a heating danger.
 

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The heat issue and stray rf,etc. is with the 1 Kw ham transmitter. I concur the wireless battery communication is likely in the milliwatt range and not a heating danger.
I expect GM to have taken into account potential interference issues, etc. with the wireless battery management system. This isn't a hobbyist project after all. The new battery would appear to be a lynchpin for many future vehicles. They have a lot riding on it.
 

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With SAW filters and Bluetooth likely frequency range only VHF/UHF transceivers would potentially cause problems. The ham radio would have to be really dirty to generate enough IM or harmonics to cause problems. The pack radios would also be very close to each other inside the battery enclosure and the 3rd order intercept point of the receiver portion could be designed high.
Jack Rickard and Colin are using Bluetooth in their designs with success. Sounds like a great idea to me.
Just don't use Bluetooth for (really) high quality audio transfer...it sux.
"Wireless" may not mean "radio".

One of the problems with Battery Management Systems, is that while the voltage of every cell in the pack is monitored to about 5mv (or less), being able to monitor the cells at the most positive end of the pack using the same circuit as monitoring the cell at the most negative end of the pack means that the voltages between those cells could be several hundred volts apart. It's not easy to measure <5mv in a pack spanning 400V (about a 100,000:1 ratio).

Wireless may mean optical fibers between each module and the pack controller, easily mooting high voltage issues outside every module.

On the other hand, perhaps there is something like Bluetooth running around inside the pack (supchrgamx) pointed to a video by Texas Intruments apparently running such a network.
 

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"Wireless" may not mean "radio".

One of the problems with Battery Management Systems, is that while the voltage of every cell in the pack is monitored to about 5mv (or less), being able to monitor the cells at the most positive end of the pack using the same circuit as monitoring the cell at the most negative end of the pack means that the voltages between those cells could be several hundred volts apart. It's not easy to measure <5mv in a pack spanning 400V (about a 100,000:1 ratio).

Wireless may mean optical fibers between each module and the pack controller, easily mooting high voltage issues outside every module.

On the other hand, perhaps there is something like Bluetooth running around inside the pack (supchrgamx) pointed to a video by Texas Intruments apparently running such a network.
Simple math and lookup table stuff from data sent from all of the modules. The system might also be a MESH network similar to "smart" meters. The individual modules only need to tend to their own cells. The module data would be handed off to a master processor likely. We will have to wait and see if anything leaks out of engineering. I would bet someone developed an ASIC solution that will be used on all systems going forward which would cost next to nothing with quantities in the millions.
 

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I would bet someone developed an ASIC solution that will be used on all systems going forward which would cost next to nothing with quantities in the millions.
An application-specific integrated circuit is an integrated circuit (IC) chip customized for a particular use, rather than intended for general-purpose use
 
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