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[enaef]

https://www.bennetts.co.uk/bikesocial/news-and-views/news/2019/december/bmw-electric-bike-wireless-charging

ZeroMark has asked for something like this five years ago:
https://www.electricmotorcycleforum.com/boards/index.php?topic=6314.msg48647#msg48647

[BrianTRice@gmail.com]

I can think of some really basic critiques that suggest that this fun and clever patent will never see production:

• Aiming to park so that the kickstand lands squarely in the center of a mat every day seems tiresome. Plugging in a cord that you can leave coiled up somewhere in your garage seems easier. (for outdoor stations, the effort seems quite similar)
• The conductors which might fit in a sidestand are not going to admit much current, so it's limited to trickle/slow charging.
• Inducing a current in the kickstand seems like it might accelerate fatigue in this structural component. It could detract from longevity.
• Fault tolerance and servicing seems harder to manage than for an electrical plug inlet.

[Richard230]

Maybe your bike will be able to be recharged from a traffic sensing loop while you are waiting for a traffic signal to change.   

[ESokoloff]

According to this....
https://www.google.com/search?q=inductance+wireless+charging+efficiency&ie=UTF-8&oe=UTF-8&hl=en-us&client=safari
wireless charging is currently (pun) only 75-80% efficient so I don't see this as a viable solution.

[Crissa]

The current probably doesn't go through the kickstand, Brian.

I always park in the same spot, so I'm tempted to put a stand on the wall there

-Crissa

[BrianTRice@gmail.com]

Electromagnetic induction meets only reluctance. The kickstand isn’t magically protected even if it’s isolated electrically.

[Doug S]

I'm with Brian. Someone had a "good idea" that's never going to work very well in practice. Not only would you have to have massive wires running through the kickstand, you'd have to have a ludicrously large bottom pad on the kickstand to get any kind of an efficient coil in there.  The kickstand would look like a piece of a baseball bat with a concrete paver stuck on the end. And come on now, how difficult is it to plug in? We've been "plugging in" our ICE vehicles forever when they need refueling.

[DonTom]

Not only sounds very flaky to me, it is also a solution to a problem that doesn't exist, IMO.


-Don-  Turlock, CA (RV-- almost home)

[enaef]

Without being an engineer I also had my doubts if such a wireless charging 'solution' really was an answer to a non-existent problem, as DonTom has put it.

Then a heretical thought crossed my mind and I asked myself if it was possible that a company would go for a patent only to confuse competitors ?

[Crissa]

The size of coil is directly related to the range, not the current.

And the diagram doesn't show the moving parts of the kickstand being part of the conductor, it shows a wire there.

You could also use the shape of the kickstand to be part of the loop.  But the loop itself never contains the entire current at any single point until the far end where it comes out.

-Crissa

[Doug S]

The size of coil is directly related to the range, not the current.

You're oversimplifying. Think about it. The full induced current has to be supported by the wire in the pickup coil as well as the wires leading from the coil to the charging circuitry (the current is identically the same throughout the whole loop). To achieve any sort of charging power, that current has to be massive. You can't use tiny magnet wire. You have to use some giant wires.

To achieve any sort of coupling efficiency between the coils, you have to use lots of turns of that high-current wire, as well as a good iron or ferrite core on both sides.

The wireless cell phone charging people struggle to pass 5 watts of charging through an area if a few square inches. Scale that up by a thousand.

[Crissa]

Only the cord leaving the coil needs to support the entire current.  The receiving coil holds only a fraction of it.  This is how inductance works; it's spread over a wide surface.

So it would be like having one of our cables strapped to the kickstand and a disk capacitor there.  It wouldn't be any bigger than a soda can or probably the '13-'19 Zero kickstand.

I'm a little surprised this isn't considered an obvious use of a prior patent, tho.

-Crissa

[wavelet]

Not only sounds very flaky to me, it is also a solution to a problem that doesn't exist, IMO.


-Don-  Turlock, CA (RV-- almost home)

IMO, that's it in a nutshell. I used to work for a VC, and maybe 80% of the entrepreneurs we met had ideas that failed that basic point. Now, sometimes a solution is developed for a need people didn't know they had (text messaging), but that's fairly rare.
There's no reason to think that this is a problem.
Incidentally, I think wireless charging for BEV cars is mostly a similar issue; it requires a lot of standardization to work.
There are niche applications where people might not be handling the charging cables themselves (very heavy cables to charge ferries, for example, are used in Scandinavia), but in those a robotic charger works well.

[Crissa]

A problem that doesn't exist for us is not the same as a problem that exists for the vast majority who don't yet use what we do.

-Crissa

[Doug S]

Only the cord leaving the coil needs to support the entire current.  The receiving coil holds only a fraction of it.  This is how inductance works; it's spread over a wide surface.

No, that's just completely wrong. It's a very well-known principle in Electronics that the current in any closed loop (only two nodes, one at each end) is identical at every point in that loop. Current is nothing but the flow of electrons, and electrons can neither be created or destroyed. It's like a closed loop of road with cars circulating around it -- unless you're somehow adding or subtracting cars, the average "car flux" is equal at every single point around the loop. They have to come from somewhere, and they have to go somewhere, just like electrons. Look up "loop analysis" if you'd like to learn more.

Mutual inductance uses a magnetic coupling between two coils of wire to create a voltage on the secondary coil proportional to the voltage on the primary coil, but all that does is push electrons around the secondary coil. There's no magic electron creation or destruction going on, and loop analysis principles still apply. Kirkhoff's laws state that the sum of the voltage drops around any loop is always exactly zero, and the sum of the currents into/out of any node is also always equal to zero.