EEVblog Electronics Community Forum
Products => Dodgy Technology => Topic started by: EEVblog on May 30, 2018, 11:58:25 pm
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Linus tested it:
But didn't us a power meter, no mention of system efficiency, or how the directional aspect works.
https://www.youtube.com/watch?v=YeNXRD8eziA (https://www.youtube.com/watch?v=YeNXRD8eziA)
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hey,
I just saw this and thought of the other wireless room charging we saw a while ago and i was wondering what you all think about this one. Real and practical or fake/unusable?
http://www.wi-charge.com/ (http://www.wi-charge.com/)
and an actual vid of it in action by a reputable source:
https://www.youtube.com/watch?v=YeNXRD8eziA (https://www.youtube.com/watch?v=YeNXRD8eziA)
Roy
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He mentioned something like 0.5W for the small phone case and 1.5W maximum for the larger receiver unit for the speaker. So not uselessly low but still significantly less than a traditional charger.
I can see niche use cases. Although the example given (cell phone chargers in coffee shop), could be achieved other ways. You could simply use a larger internally battery, and take the units to a charging dock at the end of the day for example. 1.5W * 10hr = 15WHr, not much more than a single 18650 lithium cell.
No mention of efficiency no, in the comments someone calculated around 20-30% optimal (photovoltaic efficiency combined with IR LED/laser efficiency).
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So pretty much 'Completely useless test, Holy Sh*t"
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Laser beamed IR does sent power to solar cells exactly as advertised. What they are not saying is that to get 1 watt out at the other side, you need a good 5-10 watts of optical power landing directly on the solar cell and the power efficiency of the laser to convert DC current into watts isn't also that accurate as well as aiming the beam directly on target, not to mention that they split the beam to multiple targets. And you need un-obstructed line of sight for only 1 watt of charging power, on phones today which are all display screen.
My whole point about all this tech is that Lithium-Nitrogen batteries are coming soon doubling the current battery size/mah capacity. Unless you don't sleep at all, many handheld devices will no longer need to be charged from day to day. A decade from now when Lithium Oxygen becomes available with over 3x the current capacity, not to mention the portable electronics drawing less current as well as more space for the battery as what final little streamlining there is which can be made, there will be no need to continuously charge our devices as we use them during the day.
This will be a temporary product seeing a limited use at best unless that solar cell can be hidden inside the LCD screen of a phone for near free, available on all phones being sold, it will be a fancy luxury product.
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No mention of efficiency no, in the comments someone calculated around 20-30% optimal (photovoltaic efficiency combined with IR LED/laser efficiency).
I've been talking to the marketing dude on Twitter:
(https://i.imgur.com/5OEH4O1.png)
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More, and it doesn't add up.
(https://i.imgur.com/KGurCNQ.png)
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Been going at this for 6 years and they won't release data ::)
But of course happy to target huge blogs for publicity that they know won't ask hard engineering questions - the usual story.
(https://i.imgur.com/1WTKxUY.png)
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Does anyone know how to find the FDA approval document / test results for this thing?
Asking for a friend ;)
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Tried searching here, but its all classifications: https://www.fda.gov/Radiation-EmittingProducts/default.htm (https://www.fda.gov/Radiation-EmittingProducts/default.htm)
Can only seem to look up medical devices, not radiation devices.
Is it possible the document is not public? and FDA is just saying to them, it falls within some classification and that is OK (ie power is less than xmW for a laser product).
http://www.wi-charge.com/press/wi-charge-secures-fda-approval-to-charge-all-your-devices-using-infrared-beams/ (http://www.wi-charge.com/press/wi-charge-secures-fda-approval-to-charge-all-your-devices-using-infrared-beams/)
Did some FCC searches but nothing either, probably way too early.
https://apps.fcc.gov/oetcf/eas/reports/GenericSearch.cfm (https://apps.fcc.gov/oetcf/eas/reports/GenericSearch.cfm)
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"End-to-end efficiency is comparable to an LED light."
They might as well say that the efficiency is comparable to a push-bike, except that would actually make more sense!
Perhaps they're just referring to the round white light as being as efficient as a LED bulb, because it is a LED bulb!
The intensity in their beams must be many 1000's of times that of sunlight, and yet the video cameras never pick up any dot or speck anywhere.
"Nearly 100% link efficiency." http://www.wi-charge.com/technology/ (http://www.wi-charge.com/technology/)
So now we know the efficiency, although they don't say power efficiency.LOL
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Are there cheap high power LEDs in the >1400nm range? Because I don't think I want to look into that thing and have the light reach my retina.
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The company's website shows these chargers being installed in a coffee shop. Who leaves their expensive phone on the table in plain sight in a crowded public coffee shop just so it may charge?
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"End-to-end efficiency is comparable to an LED light."
They might as well say that the efficiency is comparable to a push-bike, except that would actually make more sense!
Perhaps they're just referring to the round white light as being as efficient as a LED bulb, because it is a LED bulb!
The intensity in their beams must be many 1000's of times that of sunlight, and yet the video cameras never pick up any dot or speck anywhere.
"Nearly 100% link efficiency." http://www.wi-charge.com/technology/ (http://www.wi-charge.com/technology/)
So now we know the efficiency, although they don't say power efficiency.LOL
Calculating best case system efficiency is not rocket science:
(https://www.eevblog.com/forum/reviews/wi-charge-infrared-wireless-charging/?action=dlattach;attach=447535;image)
References:
http://www.semiconductor-today.com/news_items/2014/JAN/EPISTAR_080114.shtml (http://www.semiconductor-today.com/news_items/2014/JAN/EPISTAR_080114.shtml)
https://www.extremetech.com/extreme/252295-layered-solar-cell-can-capture-wavelengths-solar-spectrum (https://www.extremetech.com/extreme/252295-layered-solar-cell-can-capture-wavelengths-solar-spectrum)
http://brolis-semicon.com/near-infrared-components-systems/ (http://brolis-semicon.com/near-infrared-components-systems/)
I'm corresponding with them on this and have asked them to comment on my numbers.
Will do a video when they reply and see if they still want to stand behind their efficiency claim
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They just replied and are implying zero loss in the capture area because (presumably) the entire IR dot is small enough to be fully enclosed within the solar panel area.
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They have come back and said that system efficiency is "greater than 5% and lower than 27%" (the 27% figure I got from assuming no capture area loss).
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They have come back and said that system efficiency is "greater than 5% and lower than 27%" (the 27% figure I got from assuming no capture area loss).
So, its 6%. Maybe 5.5% on a bad day. :)
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They have come back and said that system efficiency is "greater than 5% and lower than 27%" (the 27% figure I got from assuming no capture area loss).
So, its 6%. Maybe 5.5% on a bad day. :)
My guess would be 10% if they can hit the target 100%
I wonder how well they track the trains in that demo. I need to get data on those trains, but you probably only have to hit a small percentage of the time with a high energy short pulse to keep the train going.
Something like a phone on a desk might need some sort of feedback to "dial in" the laser. i.e. it measures the solar cell energy output and feeds back that data as the beam hunts round.
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Does anyone know how to find the FDA approval document / test results for this thing?
Asking for a friend ;)
It's not a medical device so the FDA has no involvement. (If it were then all the correspondence between the manufacturer and the FDA would be publicly accessible though heavily redacted).
e.g., https://www.accessdata.fda.gov/drugsatfda_docs/nda/2006/021254s000toc.cfm (https://www.accessdata.fda.gov/drugsatfda_docs/nda/2006/021254s000toc.cfm) (my baby!)
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Looking at the second half of this article, if they are using the right solar cell tuned to the laser diode, the solar cell will have close to 100% efficient power recovery: http://blog.innovation4e.de/en/2016/09/12/power-by-light/ (http://blog.innovation4e.de/en/2016/09/12/power-by-light/) Though I find it doubtful that they are making their own silicon solar cells.
This does not speak to the efficiency of the laser led, optics, focus and aiming though...
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Man, I´ve already made a post for it down below same forum! |O
I do not think it´s a laser, I suspect something like a LED matrix through a planoconcave gallium arsenide lens.
The tracker shouldn´t be something more than a beacon mechanism, they target the receivers lighting up separate segments of the matrix.
The lens should also help with tracking, get fewer sense elements for larger area.
If you can see in the video, Linus is powering up at some point 2 trains and a speaker, multiple devices.
If they were not using a LED matrix and they were using a laser, they would just lose so much power output even with good and fast galvos.
Plus solar panels tend to get quite sensitive with shadows, a laser would only create a flat spot effectively making the rest of the panel look
like a shaded area.
Regards, Lefteris
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Looking at the second half of this article, if they are using the right solar cell tuned to the laser diode, the solar cell will have close to 100% efficient power recovery:
If they were getting that efficiency I think they might have mentioned it!
I'd guesstimated it at 20-30% X 20-30% which = 6%.
The TX in the test video can power up to 4 clients / trains :), which sounds like 4 lasers, we still don't know how the finding of clients works, and I still don't know why any of the very intense IR doesn't appear on the video.
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A lens filter of some sort maybe?
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They have come back and said that system efficiency is "greater than 5% and lower than 27%" (the 27% figure I got from assuming no capture area loss).
So, its 6%. Maybe 5.5% on a bad day. :)
My guess would be 10% if they can hit the target 100%
I wonder how well they track the trains in that demo. I need to get data on those trains, but you probably only have to hit a small percentage of the time with a high energy short pulse to keep the train going.
Something like a phone on a desk might need some sort of feedback to "dial in" the laser. i.e. it measures the solar cell energy output and feeds back that data as the beam hunts round.
Probably only when the line of sight is only perpendicular. What do you think happens at sheer angles?
For a wireless system, no one will always be directly beneath the transmitter, especially when transmitting to 4 devices simultaneously, devices which may be hand-held.
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All these efficiency calcs seem to ignore the power required by the scanner and control electronics. Wanna bet those draw more than 1-5 watts? That addition cuts the system efficiency down to nubbins.
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So now we know it's a laser, it pretty much has to be 1450nm ... lower and it fries your retina, higher and it fries your cornea, of course putting a couple watt inside your eyeball still isn't healthy but better than the alternatives. That's probably 1000$ worth of laser diode in there.
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That's probably 1000$ worth of laser diode in there.
Less than 300$ if they buy 1 as a time.
Less than half that in quantity.
Even less if they buy the laser die bar or chip and mount the chip on their own heatsink.
Even less if they don't need communication grade stability and uniformity along the entire laser die bar. (Sort of like accepting the B-Grade rejects as for optical power delivery charging, a 1 or 2 defective elements on the laser bar die is still acceptable.)
My guess is that they are paying around 50$ for their laser once they build in quantity. Any more and their product will be economically unviable except for the super rich.
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These aren't communication diodes, nor are bars convenient.
PS. well not fibre optic communication diodes at any rate, free space optic communication maybe ... but that's a lot more boutique.
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it pretty much has to be 1450nm ... lower and it fries your retina, higher and it fries your cornea, of course putting a couple watt inside your eyeball still isn't healthy but better than the alternatives.
Normal digital cameras and videos seem to stretch to only 1100nm-1200nm, could that be why there's no sign of the laser dot in the videos.
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it pretty much has to be 1450nm ... lower and it fries your retina, higher and it fries your cornea, of course putting a couple watt inside your eyeball still isn't healthy but better than the alternatives.
Normal digital cameras and videos seem to stretch to only 1100nm-1200nm, could that be why there's no sign of the laser dot in the videos.
That and Id expect the RED camera that LTT use for studio work to have a very good IR cut filter. You can't have a pro camera with purple halos around flames and live effects.
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If this thing really was as good as in the Linus video, safe, approved, efficient, miles ahead of ubeam, they wouldn't still be begging for partners.
www.wi-charge.com/press/wi-charge-6-months-of-industry-recognition-in-review/ (http://www.wi-charge.com/press/wi-charge-6-months-of-industry-recognition-in-review/)
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It is better than Ubean, since it actually works. But it is still super ineffecient and worthless.
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Efficiency 20%.
https://twitter.com/TheChargeGuy/status/1057298664316694529
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Efficiency 20%.
https://twitter.com/TheChargeGuy/status/1057298664316694529
Don't they use solar panels for the receiver? How are they getting 20% if most panels themselves are roughly there? Are they using something cutting edge? Does it fall under the concentrated PV umbrella? But even those are only around 30-40%.
Hmm
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I wonder if they'll have to use a very bright white light in addition to the laser to trigger blink reflex.
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Don't they use solar panels for the receiver? How are they getting 20% if most panels themselves are roughly there? Are they using something cutting edge? Does it fall under the concentrated PV umbrella? But even those are only around 30-40%.
Hmm
As a very first guesstimate of the power efficiency from emitter and receiver I usually go for 30% X 30% which is only 9%, doubling the efficiency of one of them still isn't enough to get 20%.
They claim all the energy is in a very narrow IR beam, so it's well into the CPV density levels and needing very special PV cells, I don't think they've mentioned that!
They claim 100% link efficiency, but ~50% of the intensity would be lost just getting through the IR cover.
The figures/guesstimates don't add up, I think it's mostly fake, following in the wake of uBeen.
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The figures/guesstimates don't add up, I think it's mostly fake, following in the wake of uBeen.
Exactly. It doesn't pass the sniff test.
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Efficiency for solar radiation isn't the same as efficiency for a laser (https://en.wikipedia.org/wiki/Wireless_power_transfer#Lasers).
PS. that doesn't necessarily make the link estimate realistic, but Domagoj T said the cell state of the art was 20%, which it isn't in this niche.
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PS. that doesn't necessarily make the link estimate realistic, but Domagoj T said the cell state of the art was 20%, which it isn't in this niche.
Not quite what I said, but doesn't matter.
This abstract
https://ieeexplore.ieee.org/document/4922910?arnumber=4922910
says the best they achieved with lasers and solar panels was 53,4%, which is still not enough to reach 20% when we take into consideration the efficiency of lasers.
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With a 35% efficiency laser (http://dilas.com/assets/media/products/DILAS_SB_1470nm_TD.pdf) (page 3) you can almost get to 20% with no further losses. This is COTS, though not commodity.
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They just replied and are implying zero loss in the capture area because (presumably) the entire IR dot is small enough to be fully enclosed within the solar panel area.
What if the IR "dot" accidentally gets onto your eyes? Is that safe?
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Eye safe lasers won't immediately destroy anything, because they dump power inside the volume of your eye rather than the 2D surfaces of the retina or cornea, but it's probably enough power to do damage to the lens quite quickly.
That's why I theorized about the bright white light, a blink reflex might be sufficient to make it safe.
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With a 35% efficiency laser (http://dilas.com/assets/media/products/DILAS_SB_1470nm_TD.pdf) (page 3) you can almost get to 20% with no further losses. This is COTS, though not commodity.
Add two SMPS (one on transmitter side, one on receiver) with a generous 97% efficiency and you're at 17,5%, which is not 20%.
But all that is assuming they are using the perfect laboratory condition 53,4% efficient panels. I am hesitant to assume that.
They claim near 100% link efficiency, which I am interpreting that (nearly) all the energy that leaves the laser hits the solar panel. I may be wrong, but I would guess that a laser dot is circular, while solar panels shown in Linus Tech Tips video are rectangular. It follows that the laser dot does not cover the entire surface of the panel. My question is how does this affect the power generation when we know that, with standard solar panels, partial shade disproportionately reduces panel power?
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Sectioned panels with diodes help a lot and given the power density you can make the sections quite small in this case. If you make it custom you could even have active circuits selecting the lit sections.