EEVblog #945 - Thermal Powered Smartwatches Are GIMMICKS

[Mr.TalkingMachine]

You've missed the point. Even if you have an infinitely capable phone, the fact that you need to get the phone out of your pocket to use it adds a lot of friction.

Well, now I get it, thanks mate.

[Fungus]

Even if these people manage to build something better than anyone else has built, it will only provide about 4x the power output of a run-of-the-mill peltier device. And let's be honest: that watch almost certainly has only 1/4 of the surface area, i.e. all those gains are immediately lost.

Yes, the area and radiator is going to be small and inefficient.

This is probably where it all breaks down. They're depending on a temperature difference across the watch for ti to work. I bet that difference is mostly close to zero in real life. There will only be big bursts of energy where you go indoors->outside on cold days, etc., but the rest will be tiny because the watch will mostly be at the same temperature as your wrist.

eg. My (solar-powered) Casio has a built-in thermometer but to read the ambient temperature accurately you're supposed to take it off your wrist for 20 minutes.

[AndyC_772]

Has anyone calculated the likely power outputs of the various ways to power an electronic watch that don't just involve using a battery?

I've been wearing a Seiko Kinetic watch for years. These are amazing pieces of engineering, using a rotating weight to power a tiny generator. I'm sure this type of device must be able to generate more useful power from an active wearer than a device relying solely on temperature difference.

[PeterL]

Hi group,

In the video Dave talks about the time to charge a flat battery as 2.6 years. The opposite is also true, if they ship the watch to backers with a charged battery, it will run for a while.

740mWh in the battery / 20uW = 37000 hours

4.2 years, too late for a refund.

Kind of like the LED flash lights that you shake with a lithium cell in them.

Regards,

Jay_Diddy_B

My thoughts as well, anything more than 10mWh in the battery is overkill if you ask me. (providing everything works as good as they say).

[Mosaic]

Thermal efficiency is an elusive thing. Especially energy transfer across different materials.
From the electronics POV most of the time we want to remove heat generated as a lossy byproduct of electricity use.
I did some of my own testing versus manufacturer 'claim' viz. thermal transfer PADS etc. Found that SIL pads  need serious clamping force to achieve spec sheet data, this distorts the pads and makes them not reusable as far as meeting spec.

Ended up making my own solution for 'throwaway' pads that meet real world specs for the average DIY project or repair that is superior to most other products.
https://www.tindie.com/products/Protofabtt/mylar-05mil-thermal-pads-to220--to247218-to-3/?pt=full_prod_search

As engineers we have to be careful how we interpret these 'spec sheets' there are lots of caveats and gotchas for young players that makes Uncle Bob upset.

[helge]

I'm pretty confident the watch will work in winter 
http://lab.futuretech.in/content/teg/index.html video at the end of the link

[Dr. Frank]

Dave,

on your video, I only have to criticize only your "quivering" exercise.
You have to get your butt much lower to do it effectively.   
My old basketball trainer would have punished me for that kind of execution.

Or do you still have problems to do deep knee bends, after your surgery?

Concerning this gimmick watch, I agree.
That design and product is over-engineered, overpriced, and completely inefficient, for all these three categories in relation to the supposed 'saving of earth's resources'.

What me disturbed most, was the advertising of saving energy (big energy plants!!) and to avoid waste of tons of big (!) batteries.

The inventors of such products all seem not to able to make proper calculations of energy and resource in/out balances.

In this sense, that's another completely useless product.

Frank

[nuclearcat]

Is there any battery that can have 200mah in such size, and same time wont have self-discharge >5%/month (with 200mah it is comparable with energy generated per month)?

[derGoldstein]

Is there any battery that can have 200mah in such size, and same time wont have self-discharge >5%/month (with 200mah it is comparable with energy generated per month)?

You could use a panasonic CR3032 in there, which is a 500mAh+, 30mm x 3.2mm cell. The screen of the watch is 1.2 inches, so there's certainly room for one of those in there. Now you're up to almost 7 years of use for this watch using a $4 (retail) battery...

[nuclearcat]

Sorry, i forgot to mention that i am trying to analyze what kind of battery they are using in this watch, so it means rechargeable battery.
And thats why i am concerned - their charging is extremely slow, and it means self-discharge might have significant impact on whole energy balance.

[EEVblog]

eg. My (solar-powered) Casio has a built-in thermometer but to read the ambient temperature accurately you're supposed to take it off your wrist for 20 minutes.

When developing my uWatch, the first prototype had a temp sensor on board. It wasn't anywhere near the wrist and on top of the board, and still it was pretty useless so I dropped it. The radiant/conducted heat from the wrist was just too much for it.

[imidis]

I could have sworn there was a watch that was completely human powered, you had to remember to wind it, but it didn't use any batteries. 

[Mr.B]

I could have sworn there was a watch that was completely human powered, you had to remember to wind it, but it didn't use any batteries. 

100% human powered.
It has been on my wrist for 30 years.

[rs20]

100% human powered.
It has been on my wrist for 30 years.

Do you also frequent motorbike enthusiast forums, adding random comments about your "human-powered bicycle that's never needed refueling in 30 years"?

[Mr.B]

Yes

[derGoldstein]

Don't listen to the nay-sayers.  "They" just WANT you to complacemently believe that human powered thermoelectrics don't really work.  They want your complacency.  They want your disbelief.

I know why you're here, Neo. I know what you've been doing... why you hardly sleep, why you live alone, and why night after night, you sit by your computer. You're looking for him. I know because I was once looking for the same thing. And when he found me, he told me I wasn't really looking for him. I was looking for an answer. It's the question that drives us, Neo. It's the question that brought you here. You know the question, just as I did.
Neo: What is the Matrix?
Trinity: The answer is out there, Neo. It's looking for you, and it will find you if you want it to.

It was actually the machines that used human body heat to power their world. By wearing their watch you're staying *inside* the matrix, not breaking out of it. Breaking out of it, in this context, is probably buying a different watch.

[rrinker]

 By wearing the watch you are powering the Matrix for the universe that exists inside the watch electronics.

[f4eru]

With this watch.  Then Apple will make one like it with Siri.

Nope.
You can power a basic watch with a TEG. Doing anything "smart" with it does not work, due to physical limitations of the power source.

[Halcyon]

I have an analog wristwatch somewhere which doesn't use any batteries but instead it has a rotating generator (similar to a flywheel I guess). It's designed to charge a capacitor as you move around. If left for a few days completely motionless, the arms will stop moving but will continue to count the time internally for some time. After you pick it up again and give it a shake, the arms would "fast forward" to whatever the correct time was. Worked very well actually.

[rrinker]

With this watch.  Then Apple will make one like it with Siri.

Nope.
You can power a basic watch with a TEG. Doing anything "smart" with it does not work, due to physical limitations of the power source.

 And therein lies the rub. The technology isn't phony, it really does work. The problem is, not for the current levels required by even the most frugal of smart watches.

[Mosaic]

It appears that marketing is the most important 'pitch' for inventors....
http://www.inventionstatistics.com/Innovation_Risk_Taking_Inventors.html

[f4eru]

a panasonic CR3032 in there......  a $4 (retail) battery...

interestingly, I worked at a place where we would produce a HUGE LOT of products with these panasonic CR2032 (in the millions per year)

In that sort of quantity, the purchase cost for one CR2032 was .......
.....
.....
.....
.....
8 euro cents !!!!
0,08 Euro !!