EEVblog #1092 - Wi-Charge IR Wireless Charging - Fact or Fiction?  - Page 1
Forum section: electronics / general

author: Barny
author_rank: Frequent Contributor
timestamp: June 06, 2018, 07:13:26 am
content: Running the numbers on the W-Charge Infrared laser wireless charging system, does it work?, is it practical?, what is the efficiency?, how much power can it deliver?, is it dangerous?And the laser power is HOW MUCH?!CORRECTION: The laser output power was stated incorrectly, it was assuming the input power to the laser when it should have been the optical output power. The correct number for a 45% solar cell and zero other losses is 11.1W laser power, not 18W. Still the same class of laser and just as dangerous.In response to the Linus Tech Tips demonstration.Also some talk on the Energous RF Wireless energy boondoggle.

author: Barny
author_rank: Frequent Contributor
timestamp: June 06, 2018, 07:18:46 am
content: I hope this charge-system gets available for a good price here in Europe.It starts to get really hard to get other laser then simple laser pointer as a private person thanks to some idiots which decides to point them to landing / starting planes.The lasers and laser driver in the charger would be nice to cut & engrave wood and perhaps thin sheets of steel.

author: janekm
author_rank: Unknown
timestamp: June 06, 2018, 08:09:38 am
content: Quote from: Barny on June 06, 2018, 07:18:46 amAll that's needed to transform this gadget into a whole-room engraver is a firmware modification

author: Barny
author_rank: Frequent Contributor
timestamp: June 06, 2018, 08:20:29 am
content: I don't think so.It would extreme hard to focus the beam longer then a few mm.But if they switch to UV-Laser, it could be used for mask less exposure of PCB's

author: G7PSK
author_rank: Super Contributor
timestamp: June 06, 2018, 08:30:37 am
content: I am waiting for BMW to upgrade this for there car charging system, just think power on the go while driving down the motor way. All delivered via a weapons grade laseror

author: fls
author_rank: Contributor
timestamp: June 06, 2018, 09:56:26 am
content: Maybe stupid question, but does the unit contains one '20W' power diode or maybe several smaller ones?Marketing talk still holds the '5W delivered power' if you have 5 devices charged by 5 diodes (or maybe even 10 diodes?)It does not mention that the 5W is per device by 1 diode.Or am I missing something?

author: Psi
author_rank: Super Contributor
timestamp: June 06, 2018, 10:08:54 am
content: Unlike with visible laser diodes, extremely high power IR laser diodes are relatively affordable.$300 can get you a 10W solid state IR laser diode and ive seen well over 50W available.They aresuperdangerous though, you get no warnings or 2nd chances, one reflection and you are blind.. for the rest of your life.https://www.aliexpress.com/item/Industrial-Design-10W-10000mw-808nm-laser-diode-module-Brass-18mm-C-mount-IR-laser/32868308008.htmlhttps://www.alibaba.com/product-detail/fiber-laser-50w-100w-high-power_60490362832.htmlhttps://www.aliexpress.com/item/100W-oflaser-machines-Diode-Side-Pump-laser-module-for-sale/32859195813.html

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: June 06, 2018, 10:18:09 am
content: Direct sunlight in the best case delivers 1kW/m2 that's 0.1W per square centimeter IIANM. This thingy say 5W into what, 5 square centimeters or so? That's 1W/cm2 or about ten times as much? Or is that 5W figure after the receiver conversion losses? If so it's perhaps not tens but hundreds of times more powerful than the sun /cm2 !﻿

author: Barny
author_rank: Frequent Contributor
timestamp: June 06, 2018, 11:13:28 am
content: Quote from: Psi on June 06, 2018, 10:08:54 amThe problem isn't the price.The problem is to get them through the import customs.The block nearly all laser and periodically even LED's which are coming from china.(Specially here in Austria & Germany.)Till now England was a way to get parts which otherwise get blocked at customs.But they decided to don't play with us anymore.

author: janekm
author_rank: Unknown
timestamp: June 06, 2018, 11:20:42 am
content: Quote from: fls on June 06, 2018, 09:56:26 amI did a little skimming of the patents, which are very interesting. According to the patents, is not using a regular laser diode at all but rather a "freespace" lasing system, that is the laser cavity is formed between the transmitter and the receiver (both of which have retroreflectors).Remembering that "laser" stands for "light amplification by stimulated emission of radiation", that is in this system, light emitted from the transmitter is reflected by the receiver, then reflected & amplified by the transmitter, repeatedly.This is a very smart idea since it means that anything interrupting the beam stops the lasing directly. Additionally they can use it with some adaptive optics to focus / track the receiver.Theoretically multiple transmitters could be employed, afaict, since retroreflection would allow each to operate independently (though I wonder about interference?).The biggest issue of course is if some proportion of the light is scattered or reflected away from the intended optical path.Like Dave pointed out it all seems a little overkill for charging mobile phones, but there are likely real applications in other fields (sensor networks? micro-satellites?).

author: Psi
author_rank: Super Contributor
timestamp: June 06, 2018, 11:56:41 am
content: Quote from: Barny on June 06, 2018, 11:13:28 amThey block laser pointers, not products that contain lasers.Otherwise you wouldn't be able to buy any DVD / Blueray writers which contain 400mW lasers. Or superfast laser printers with high power diodes.

author: Barny
author_rank: Frequent Contributor
timestamp: June 06, 2018, 12:40:04 pm
content: Yes.But why should I buy a complete laser cutter / engraver when I only need the laser unit for my millAns good luck, getting a complete laser cutter with all its paper work as a private person through imort customs.A button cell is enough to refuse import.(µCurrent fom Dave get hit from this stupide rule too.)@janekm :Isn't a exact matching length between the mirrors needed for the laser to work?

author: apis
author_rank: Super Contributor
timestamp: June 06, 2018, 01:14:01 pm
content: Even if they can make this safe and usable, it won't be cheap enough to become mainstream.I can't even think of a niche application for it but maybe there is one.Nice gimmick though.

author: maxwell3e10
author_rank: Frequent Contributor
timestamp: June 06, 2018, 01:22:45 pm
content: Quote from: janekm on June 06, 2018, 11:20:42 amThis is hard to believe, both because the receiver looks like a simple solar cell and because it would be extremely difficult to maintain alignment of the laser cavity, especially on the moving train demo.If I were to built a system like that, I would have a low-power flashing IR photodiode, like they use in remote controls, installed in the receiver. The base unit detects this light and uses it both to align the IR laser and as a safety feature. If the IR modulated signal gets blocked, the laser is immediately shut down. This could be done in less than 1 microsecond and so would prevent somewhat the laser getting scattered when something shiny blocks its path.

author: StillTrying
author_rank: Super Contributor
timestamp: June 06, 2018, 03:26:07 pm
content: Quote from: maxwell3e10 on June 06, 2018, 01:22:45 pmMy previous reply to that part was quite simple!https://www.eevblog.com/forum/chat/infrared-laser-wireless-charging/msg1292229/#msg1292229QuoteYou could be right! The IR could be coded so that you don't get burnt fingers every time you change TV channels.Good #1092 video, problem is there's now 6 separate threads on this thing.

author: madires
author_rank: Super Contributor
timestamp: June 06, 2018, 03:34:18 pm
content: I'd assume that "total power delivered" means the total power delivered across the complete lit area. For safety reasons they have to widen the beam anyway. Laser class 1 and 1M are fine for consumer stuff, but any higher class would involve a lot of safety regulations. Still, as nearer you get to the laser source as narrow the beam will become. With tracking the receiver to send a narrow beam for maximum power transfer they would exceed Class 1(M) anyway. I have strong doubts that they may sell the Wi-Charge to consumers, and also about the efficiency. If my assumption about the delivered power is right we would be talking about <0.1%.

author: grythumn
author_rank: Contributor
timestamp: June 06, 2018, 03:36:45 pm
content: If they can get the power up a bit higher than 5W, it might be useful for long endurance personal mini drone cameras. Run it off a small ultracap, and make them tiny. Right now some of the nano drones run around the 10-30W range.-Bob

author: bitwelder
author_rank: Super Contributor
timestamp: June 06, 2018, 07:33:18 pm
content: Quote from: janekm on June 06, 2018, 08:09:38 amBecause why not, I'm pretty sure soon or later this gadget will get its own internet connection, there will be a good chance to have a remotely hacked device totally out of control (and because it's IR, nobody would notice it)

author: Barny
author_rank: Frequent Contributor
timestamp: June 06, 2018, 08:10:25 pm
content: This Charger would be the ultimative "TV b gone"Imagine a charger like this in an consumer electronic market.

author: hans
author_rank: Super Contributor
timestamp: June 06, 2018, 10:22:29 pm
content: Class 2 laser classification is drawn at 1mW. Even at that power level, it assumed that the blinking reflex of the eye prevents long exposure. When you suppress that reflex then damage could appear. Unfortunately the eye reflex doesn't work for infrared, so you're directly exposed. I wouldn't though any infrared laser without a good pair of laser glasses.If they are transmitting a couple of Watts of light continuously out and 1mW is the safety threshold, then just a reflection of 1:1000 power is enough for some serious trouble. Basically anything that does not create a diffuse reflection is a problem.Maybe they use the most diffuse laser beam they can get away with, but I highly doubt given the very small area of the device light panels.I agree with the argument in the video. This seems to be an excessively expensive, complex and potentially dangerous solution that is solved with a 20$ powerbank and a simple charging routine. Or just put a freaking outlet where you need power.

author: nctnico
author_rank: Super Contributor
timestamp: June 06, 2018, 10:42:52 pm
content: Couldn't resist...

author: EEVblog
author_rank: Unknown
timestamp: June 07, 2018, 01:21:13 am
content: Quote from: hans on June 06, 2018, 10:22:29 pmTheyhaveto be doing that to deliver 5W continuously, it's a basic law of physics. In fact it's likely in the order of 20W optical power at least. They have basically admitted to me it'sat least11W optical.

author: EEVblog
author_rank: Unknown
timestamp: June 07, 2018, 01:26:50 am
content: Quote from: maxwell3e10 on June 06, 2018, 01:22:45 pmAnd that's another thing I forgot to mention in the video.The patent mentions retroreflectors, and a previous prototype does that, but I'm not sure if the latest one does.Their entire concept from day one was doing away with one mirror in the traditional laser cavity and using the retroreflector in the receiver to complete the cavity. i.e. it becomes an "external cavity" laser.The idea is that if you break that external cavity beam, the laser effectively automagically shuts of instantly.Scatter is still a major danger though.

author: maxwell3e10
author_rank: Frequent Contributor
timestamp: June 07, 2018, 01:50:25 am
content: Quote from: EEVblog on June 07, 2018, 01:26:50 amSemiconductor lasers have a large intrinsic gain so they would emit a lot of spontaneous emission light even without a cavity and even if they have a very high quality anti-reflection coating on the output facet. One would only get a factor of 3-5 reduction in power when the retroreflector is blocked, not much more.

author: StillTrying
author_rank: Super Contributor
timestamp: June 07, 2018, 02:29:04 am
content: Quote from: EEVblog on June 07, 2018, 01:26:50 amI don't think anyone believes an "external cavity" laser exists, I certainly don't.I've watched the linus vid again closely, I think there's a chance it's faked!

author: SMB784
author_rank: Frequent Contributor
timestamp: June 07, 2018, 07:53:01 am
content: Quote from: EEVblog on June 07, 2018, 01:26:50 amHowdy Dave,Your point about safety is in fact the most salient reason why this device cannot ever come to market, and likely doesn't actually exist.I did a couple of back of the envelope calculations (that I will show tomorrow) that demonstrate that this thing would far outshine the sun if it hit any surface, and it wouldn't even be visible due to the NIR nature of the laser, so you would have no idea that you were going blind until it had already happened.I wouldn't even be able to get safety clearance for this device in my laser lab; there is no way this device is FDA cleared for anything other than some R&D environment, and if the video is actually a real prototype at the stated specifications, the poor man in the video is now almost certainly blind.

author: G7PSK
author_rank: Super Contributor
timestamp: June 07, 2018, 08:48:05 am
content: A 5 KW laser will cut through 25mm of steel (https://www.msslasers.com/used-lasers-for-sale/trumpf-5030-fiber) so what damage will 20 watts do, it should be able to cut tin foil.

author: EEVblog
author_rank: Unknown
timestamp: June 07, 2018, 09:05:13 am
content: Quote from: StillTrying on June 07, 2018, 02:29:04 amI greatly doubt it's fake, but it's almost certainly a highly engineered demo, likely one that needs some potential massaging to get working.In fact it's not new, they have had the speaker and train demos for a long time now.

author: janekm
author_rank: Unknown
timestamp: June 07, 2018, 09:26:33 am
content: This blog which is linked as the official blog from the wi-charge site has a curious article today:https://chargeguy.blogspot.com/2018/06/is-line-of-sight-required-for-wireless.htmlSuggesting that using reflections off random surfaces in the environment to overcome obstructions would be practical for the wi-charge solutions seems a little odd (though it would kind of mesh with the free-space laser concept, but hard to imagine that would work bounced off of other surfaces, not to mention the issue of scattering...)

author: apis
author_rank: Super Contributor
timestamp: June 07, 2018, 10:25:58 am
content: What if you put a small reflective object, like a needle, onto the receiver while it is charging. Instant blindness (from the reflections)?

author: madires
author_rank: Super Contributor
timestamp: June 07, 2018, 11:00:47 am
content: Using reflection would decrease the efficiency dramatically more. The surfaces of your furniture and walls have different reflection factors (from absorbing up to full reflection) and the reflected IR will be spread even more, i.e. less power per area. Some people think that they can ignore basic physics.

author: Psi
author_rank: Super Contributor
timestamp: June 08, 2018, 08:50:13 am
content: Quote from: EEVblog on June 07, 2018, 09:05:13 amYeah, i made a thread recently showing just how efficient you can get precious metal brushed DC motors.12VDC motors that have enough starting torque from 65mV input.https://www.eevblog.com/forum/chat/post-a-guess-on-the-min-starting-voltage-for-this-brushed-dc-motor/msg1560541/#msg1560541I'm sure you could make a train using those kind of motors combined with really high quality ball bearings on the wheels.You'd end up with a train that moves from a really small amount of energy, compared to a normal toy train, but at ridiculous cost.

author: lem_ix
author_rank: Regular Contributor
timestamp: June 08, 2018, 11:07:25 am
content: Power and lasers, what could possibly go wrongBlinding people aside, I wonder if this tech will end up in a completely different field.

author: fatboy77
author_rank: Newbie
timestamp: June 09, 2018, 02:08:06 am
content: Yeah i find the trains in all videos i saw are too stable considering they have no batteries inside...The testers should show us IR glasses view or PIR or somethingKeep up the good job!

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 09, 2018, 03:50:35 am
content: What if the light source is not a laser but a conventional light source like LEDs or even incandescent bulbs? 250W heat lamps are easy to get off the shelf and are relatively safe to use.

author: SebastianCurefab
author_rank: Newbie
timestamp: November 15, 2018, 12:56:11 am
content: Hi all,released in September or October 2018 there are some papers with actual numbers and graphs for tech-savvy people.The end-to-end-efficiency is about 10%-20% with an additional 4W-5W lost (if I interpret them correctly). Not bad!https://arxiv.org/pdf/1801.03835.pdf(Fig. 23)https://arxiv.org/pdf/1802.01570.pdf(Fig. 4)https://arxiv.org/pdf/1809.09364.pdf(Fig. 11)The actual optical window of the receiver is just 15x15x6 mm in size, the rest is electronics (e.g. voltage conversion).Source:http://www.wi-charge.com/sep-2018-webinar-on-integrating-wireless-charging/A photovoltaic cell is used below a diffusor below the output beam of the receiving mirror. So the complete area of the PV cell is used.The technology can be improved with better PV cells, greater distance, faster switching (they state it activates in 2s, but can be much improved).What if they use a wavelength which goes through the body?Best regards,Sebastian

author: StillTrying
author_rank: Super Contributor
timestamp: November 15, 2018, 04:12:52 pm
content: https://arxiv.org/pdf/1801.03835.pdf(Fig. 23)https://arxiv.org/pdf/1802.01570.pdf(Fig. 4)https://arxiv.org/pdf/1809.09364.pdf(Fig. 11)All them graphs and calculations haven'tconvincedfooled me!"What if they use a wavelength which goes through the body?"Beamed X-rays could allow non-line-of-sight charging.

author: EEVblog
author_rank: Unknown
timestamp: November 30, 2018, 01:09:27 pm
content: They have a new dev kit, I wonder if they'll send me one?https://www.netans.com/2018/11/19/wi-charge/

author: StillTrying
author_rank: Super Contributor
timestamp: November 30, 2018, 02:54:46 pm
content: There must be all kinds ofinteresting tech stuffinvolved in their high power Open Cavity Scanning Laser, but it never gets mentioned anywhere, I don't think they realize or know what's involved!I'm afraid I still think it's faked with just PV cells.

author: EEVblog
author_rank: Unknown
timestamp: June 25, 2019, 03:32:12 am
content: It's back again, with an article on All About Circuits:https://www.allaboutcircuits.com/news/future-of-power-infrared-beams-next-step-in-wireless-charging/

author: volkspolizist
author_rank: Newbie
timestamp: July 07, 2024, 05:37:55 pm
content: Yesterday Linus talked about this on the WAN show, you may want to take a look at this;https://youtu.be/WgwQDQD6dII?t=7094He said "there is nothing to debunk"

author: thm_w
author_rank: Super Contributor
timestamp: July 10, 2024, 12:56:52 am
content: Quote from: volkspolizist on July 07, 2024, 05:37:55 pmThe needed context here being "it has many limitations, number of devices and power draw".There is nothing to debunk because he tested it and it worked. That doesn't mean it is useful.

author: EEVblog
author_rank: Unknown
timestamp: July 10, 2024, 06:47:36 am
content: Quote from: thm_w on July 10, 2024, 12:56:52 amThat applies to almost everything I have ever debunked. They all "work".