Featured Post

End of an Era - Thoughts on uBeam Founder Stepping Down as CEO

Earlier today news was broken by Axios that uBeam founder Meredith Perry had "stepped down" as CEO to spend more time with her fa...

Monday, January 8, 2018

Tech Journalists: Questions for Energous at CES

Tech journalists can come under a lot of fire for failing to ask the difficult technical questions many in the field want answered, and sometimes let companies away with pretty egregious statements. Now, reporting aggressively can lose you access, but for the many journalists who want to do a good job and ask the right questions, how to do basic preparation when a topic can require years of study to truly get to grips with?

To help out those journalists going to CES and will be seeing Energous' new system in operation, I thought I'd give some handy helpful questions so there's no getting the most from your interview time. (Of course, I'd tell you to read all my blog posts on Energous too, but let's make it easy...)

Speak to a technical expert - don't take the company word at face value
First point - talk to other engineers or physicists like me who can help you - ask these questions of Energous. Seriously, you can get in touch with me here, I can put you in touch with others, and there are academics and industry experts who will help out. Don't take the initial answers the company gives, they'll try and dodge if you ask good questions. Notice where they get uncomfortable and press there. Get specifics, don't allow them to handwave. If you ask for a number and don't get it, but do get a wordy story, they're avoiding giving it to you. They have FCC data now, no excuses. Ask again and again until you get that number.

What is this thing?
Second - know what they're showing. They used to claim it will charge phones, they're a long way from that. Their FCC Part 18 approved device needs a safety cutoff because of international limits, to charge a device at around 100 to 200 mW at best, wastes at least 99% of the energy, has a tiny limited zone it can be used in, is a fraction of the performance of what was promised over the last few years, and those safety limits will likely prevent them increasing power or distance.

So here we go:

What's your use-case for this system? Who buys it? How long will it take to charge my phone? Can people use their devices while they charge? Do I have to stand in a limited area. Will moving affect charging? What's going to be the first product and when?
Alarm bells if they can't give you a clear answer or waffle on about chargeable clothing or the like. 

Are we, right now, operating under the same safety limits and other restrictions a consumer system would have to?
If not, why not? What's the difference? Am I safe? (Familiarize yourself with SAR - International safety limits)

Why do you need a keep-out-zone? Why is it at 50 centimeters? 

What size is that device that's being charged? IPhone X? Or Fitbit?
The dimensions matter. Ask how power would change with a much bigger or smaller device. Get numbers. If it's a wearable, ask about phones.

What much power is that device you are showing receiving?
Now you might get get the answer "it's really variable and depends on circumstances" to which the next question is:
OK, so how much power with this receiver under ideal circumstances of position and orientation?
Ask what those conditions are. Position. Distance. Orientation. In numbers. (See the very bottom for some comparison numbers)

Can you prove that, with a power meter? Don't let lighting LEDs wow you. Demand proof.

Is that within or outside the "keep-out" zone? Company statements last week indicated that there would be less than 200 mWatts received at the edge of the "keep-out-zone" of 50 cm. Are we exceeding international SAR limits right now? 

How long to charge this device at that rate?  How long would an iPhone take?

What happens if it rotates at an angle, or I move it further away? Maximum distance, and how power dips as the receiver rotates.

Is that RF energy received, or actually converted to power at the battery? Odds are it's a 60 to 70% conversion efficiency from one to the other, they'll want to give you the bigger of the two.

What's the efficiency? Is that calculated from the wall socket, or the transmit antenna? Efficiency is calculated with a power in, and a power out - make sure you know where those two powers are measured. You want wall socket to battery.

Your MS300a receiver: Why is it so much thicker than a phone? Does it have any batteries or charge storing capability? The FCC documents say 300 mW received, is that RF received or converted at the battery? At what distance does it receive that much? (Added 1/9/18)

Those are the initial questions to ask - finding out power versus distance, orientation of receiver, efficiency, and whether you're in the "keep out zone". Don't be put off by "oh that number depends on the circumstances" - press them with specific circumstances. Ask for "best case scenario" for a consumer, then ask what distance, orientation, are for those powers and efficiencies. Then ask about different circumstances of distance and orientation. Watch the wording carefully - slight differences in terminology matter.

Now the most important question:

Why isn't the system putting out more power? "FCC Part 18" is supposed to be unlimited power. Only charging at ~100 mW? Why not more? What's stopping you? Are you operating at the international SAR limit? If not, how far away from it are you? How will you get more powerful systems if this is a limit? If they are at these safety limits, it's indicative the power can never increased further in any future products. 

Update 14th Jan: It looks like Energous are trying to pre-empt SAR questions by stating their system "transmits at well below the SAR for phones" but not stating what the limit is or what they are transmitting at. Journalists, ask for numbers for both! Their response here indicates they are sensitive to this question.

How much power is the transmitter sending out? Is that conducted power? ERP? EIRP? Ask them to be very specific, those terms matter. (I expect for this device it's 10 Watts transmitted, 30W ERP, 50W EIRP - see how different they are?) Once you get conducted power, ask for the wall socket power. They do know it.

How large are your "pockets" of power? Dimensions please. Your FCC SAR Report shows them as at least 50 centimeters across (half power). Why so big?

How well does the power track the receiver? Are the highest regions of power always on the receiver? The FCC SAR report shows that maximum power isn't always at the receiver. Why not? 

In January 2015 here at CES you gave demos and said "up to 12 devices, up to 15 feet, up to 4 Watts". So what are those numbers for this system? How long until you get to those 2015 numbers? How close will you get? What's stopping you getting there?

In January 2016 here at CES you showed antenna receiving power at 1.6 Watts. Why can't you do that now? What's the difference?

Earlier this year you said this would work with the WattUp Mini. That's 5.8GHz and contact charging, this is 0.913 GHz. Will they operate together? Why not? Will they ever? What changed? Did the FCC deny you certification at 5.8 and 2.4 GHz?

The FCC Approval says your safety system won't detect inanimate objects. What happens if someone falls unconscious in the keep out zone and just their head is in there. Will the system start working again after 30 seconds and expose the person to dangerous energy? What happens if the sensors get blocked? Under what other circumstances might it fail?

What technology does the safety detection system use? IR/Radar? What frequency? Is it close to 913 MHz? Shouldn't it use the same energy as the power transmission? Why did you design a safety system for motion, not presence of people or pets?

Why did the executives and so many big shareholders sell large amounts of their stock last week?  Aren't they confident of where the company will be moving forward?

How did you get the FCC Chairman to tweet about Energous? Isn't that against government rules to single out companies like that?

Finally, a question for me. Do you use the same type of antenna on send as receive? What type are they? Half-wave dipole, patch, or something else?

That'll do to begin with - I'll add more as I think of them. And to repeat - talk to someone who understands the technology, this is a tricky subject, and Energous are very polished in giving vague answers!

Power numbers
1 Watt (W) is 1000 milliWatts (mW) which itself is 1000 microWatts (uW). So 1 Watt is 1 million microWatts
An iPhone needs between 500 and 1000 milliWatts (mW) to start charging. So that's 0.5 to 1 Watts.
Qi charging/AirPower in the latest iPhone is 7.5 Watts. It will likely fully charge the phone in 2 to 3 hours.100 mW is 75 times slower than this, 30 mW is 250 times slower than this.
Apple AirPods have a 1.5 Wh battery, so around 15 hours to a day to charge at 100mW. If you stand still in a tiny charge zone.

Update 1/8/18: Looks like they're hiding their technology from most, so only tame journalists are likely to get to see it. Still, now they've no excuses for not asking the right questions in their article. Hear that David PogueFrom their press release:

Energous will be taking private meetings and demos at the Venetian, alongside Dialog, on an appointment-only basis, at CES 2018, the world's largest consumer electronics show, January 9-12 in Las Vegas, NV


  1. It's only January 8th and already you're off the Energous 2018 Christmas Card list. I'm sure Energous management are reading this page (Hi there!) and thinking "fuuuuuuuuuck that guy" ;-)

    1. From the coverage so far, it seems no journalists bothered to read any of these questions, so perhaps they weren't so worried...

  2. bah, those energous guys. i've been working with wireless charging for awhile and their claims are all wrong. btw, i've got real efficiency #'s if you're interested. hint, even your numbers are way high.....

    1. I'm always interested in a healthy discussion about technology, if you've got some calculations I'd be interested in seeing.

      As for my numbers being high - I always try to work giving the most advantageous interpretations, so I can't be accused of deliberately going for worst case. When even generous assumptions show it's a fool's errand, it makes the point all the more obvious.

  3. Hiya. Would be interested to get in touch with you for a newspaper piece I'm writing on this subject... Possible? My email address link is at the bottom of this page: http://rhodri.info – thanks in advance.