[gunrunnerjohn]

Gee, you're not posting any new information on the actual topic being discussed. Making your own charger is not answering the question, I'm not going to rip the charger out of my Sorento and replace it with a coil of wire there! Also, simply coupling a signal between two coils is not proving anything, the question is why can't we wirelessly charge through an aluminum case.

If it were one or even two of the chargers that was affected, I'd point the finger at the chargers. The fact that ALL the wireless chargers I happen to have ready access to, including the one that's built into the car, fail with a sheet of aluminum foil between the phone and the charger. BTW, I just found a couple more in a box that were of a different manufacturer, so now it's six for six that fail to charge through a single sheet of aluminum foil.

I don't pretend to understand in copious detail the in's and out's of how cellphone wireless charging is done or exactly why they won't work through any kind of metallic backing. I actually sort of see that your argument seems on the surface to make sense. However, the plain facts are, wireless charging as it's currently implimented in virtually all phones, if not really all phones, does not work through aluminum foil. I tried an iPhone 11, the Galaxy S20, and my older Galaxy S8+, exact same result with all of them, they don't notice the wireless charger at all. The chargers either alternate between sensing and a brief pulse of charging status or just sit there and visibly do nothing with their status LED, depending on the specific manufacturer of the charger.

It's also telling that Google had to cut a hole in their aluminum shell to allow the wireless charging to function. What I don't understand is why you think you're smarter than all the engineers that have worked on this problem and have not come up with a workable solution! I'm pretty sure someone has to have analyzed this issue to death, and probably somewhere there is a rational explanation of why this doesn't work. What I know for certain is, with the current generation of cellphones and chargers, it doesn't work!

 

[ecanderson]

I'm pretty sure someone has to have analyzed this issue to death, and probably somewhere there is a rational explanation of why this doesn't work. What I know for certain is, with the current generation of cellphones and chargers, it doesn't work!

When someone actually publishes something sensible (that article quoted was weak - or OK - just plain incorrect in a critical assumption made by the author), I'm looking forward to hearing what the challenge really is with this current crop of induction chargers was, too.

All I was ever refuting was that there is something inherent in aluminum (or any other low permeability material) that is capable of blocking a magnetic field. I could imagine a design review where it was decided that risks to having other objects placed in the field (e.g., metal, and unidentifiable as a chargable device) might be reason for a charger shutdown. If these chargers are responding to non-ferrous metallic objects for some legitimate design reason, and shutting down as a result, that's another thing altogether.

Remember how I got into this discussion. It was due to this statement:

"Metal case = faraday cage = no magnetic waves = no inductive charging "

 

[gunrunnerjohn]

Well, you can quibble about one statement, but the bottom line question was: Why doesn't wireless charging work through metal cases. That's the question I'm working on.

 

[ecanderson]

As I say - just a guess, but it's possible that there's a design requirement that prevents the charger from operating in the event that some foreign metallic material is placed on a charger of the currently popular design. That would certainly explain it. And from what I could tell from the Qualcomm article, they seem to be looking for a way around that.

 

[gunrunnerjohn]

It seems the charger is actually sensing the foil is there as they react when just the foil is placed there. So, obviously, there is some kind of "load" that is being sensed just with the aluminum foil. Since every charger I have does a similar thing, I suspect there's something about the intervening metal that they don't like. There isn't much information about the true technical details of the charging process anywhere I have found.

One detail that may explain the issue is the fact that for maximum power transfer the resonant frequency of the charging and receiving coil have to be the same, I wonder if the tinfoil is skewing the resonant frequency of the charger and it's detecting the problem?

Here's a slightly more informative article on wireless charging that seems to explain the tinfoil effect. Wireless charging explained: What is it and how does it work? Apparently, it's detected as a "foreign object".

 

[ron1004]

Eddy currents generated in the aluminum act like a short circuit secondary coil of a transformer and this in turn overloads the primary coil, in this case the primary coil being the cell phone induction charger.

 

[ecanderson]

Interesting article. Clear and concise.

Just had a look at the Qi spec itself. I think I see where the problem is -- not in power transfer, but in communication:

"Regulation of the output voltage is provided by a digital control loop where the power receiver communicates with the power transmitter and requests more or less power. Communication is unidirectional from the power receiver to the power transmitter via backscatter modulation."

The phone designers that used aluminum cases probably considered only the fundamental physics without realizing that this part of the specification was going to break the design.

 

[gunrunnerjohn]

Yep, I thought that was finally the article that explained why the charger just shuts down under the foil. The interesting thing is, even with no phone near it, it still knows the aluminum is there, so there is some loading effect of the aluminum or they wouldn't know it was there. Also, a chunk of lead or a chunk of steel on the plate elicits exactly the same response from the charging status lights. Even a small piece of aluminum foil befuddles the charging sensing circuit. I cut a 1" square, it's enough to annoy the charging pad.

 

[ecanderson]

Weird. That video only comes up as a 1 second thing.

 

[gunrunnerjohn]

It was only a 2 second video to show the charger blinking between charge and looking for the phone with the little 1" piece of aluminum foil on it.

 

[octavian_kia]

Looks like some 2020 Hyundai models are getting wireless Android Auto on a recent update (that did not have it prior):

Software update for non-nav infotainment system - fixes...

There is a software update to the non-navigation infotainment system. This update is specifically geared towards fixing wireless connectivity issues with Apple CarPlay and Android Auto. Here's the link: Notice | Official Hyundai Motors Navigation Update Website (note: the 2020+ Sonata use the...

www.hyundai-forums.com

I think the modem/chip in the 2020 has a module that supports wireless connections, but who knows if other requirements are met (ie. a wifi antenna, etc).

Without getting too excited, I do think it's worth keeping an eye on. I couldn't confirm if our 2020s had the right chip for it but from my googl-ing earlier this winter the needed chips have been available for a while, and it appears my car has a wifi module of some sort.

 

[mike_pl]

This update is for a non-navigation units and it fixes wireless connectionţ. Not adding. Fixing.

Or am I wrong?

 

[octavian_kia]

This update is for a non-navigation units and it fixes wireless connectionţ. Not adding. Fixing.

Or am I wrong?

It's fixing the issue on units that were shipped with the feature on, and enabled it on others. Some people in the thread had to force the update in the engineering mode area which is something I wouldn't do atm.

 

[mike_pl]

Ok, but it's still only for non-navigation infotainment system. Sorento MQ4 non-navigation infotainment system already has wireless AA.

Don't get me wrong - I really want to have wireless AA on my Bose infotainment system. But imo this Hyundai update doesn't mean anything to us.

 

[octavian_kia]

Ok, but it's still only for non-navigation infotainment system. Sorento MQ4 non-navigation infotainment system already has wireless AA.

Don't get me wrong - I really want to have wireless AA on my Bose infotainment system. But imo this Hyundai update doesn't mean anything to us.

Understood And yes, you could be right but I want to keep an eye on it and see how it works out. I think we have the hardware for it.

 

[mike_pl]

Also, the same update is live for KIA: Notice | Official Kia Motors Navigation Update Website

But as I mentioned, it's not meant for Bose infotainment system which is Gen5.

 

[mike_pl]

 

[mike_pl]

Understood And yes, you could be right but I want to keep an eye on it and see how it works out. I think we have the hardware for it.

Yes, we have hardware for it.

According to the engineering menu, the 10.25" head unit is equipped with BCM89359 5G WiFi/Bluetooth Smart 2X2 MIMO Combo Chip with RSDB Support. Its key features are:

• Optimized for seamless interaction with enhanced wireless applications and feature-rich systems like Apple CarPlay and Google Auto Link, the BCM89359 device is the first WLAN combo architected specifically for multi-band concurrent automotive infotainment and telematics operation.
• RSDB support enables simultaneous connectivity to the 5 GHz and 2.4 GHz bands, improving throughput and latency when using multiple applications.
• Integrated 5G WiFi technology provides the bandwidth required for multiple high resolution in-car displays, allowing uncongested 5GHz video to coexist concurrently with Wi-Fi Internet access and 2.4GHz Bluetooth hands-free audio.
• 2x2 MIMO technology delivers twice the Wi-Fi performance of any other solution on the market today, providing the highest throughput in-car network possible for multiple user experiences.
• A dedicated Bluetooth antenna enables concurrent operation of Bluetooth and WLAN applications and employs advanced coexistence algorithms to maximize voice quality and data access speed in simultaneous operation.