[HN Gopher] New battery-free technology can power devices using ...
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New battery-free technology can power devices using ambient RF
signals
Author : ohjeez
Score : 60 points
Date : 2025-03-02 17:25 UTC (5 hours ago)
(HTM) web link (news.nus.edu.sg)
(TXT) w3m dump (news.nus.edu.sg)
| amelius wrote:
| Is this going to drain __my__ phone battery more?
| tejtm wrote:
| you transmit, it receives. To avoid draining battery, don't
| transmit.
|
| that said I expect "feed me" attacks eventually. emit small
| signals that induce a big response
|
| ... hey maybe I can finally get something useful from
| advertising.
| snovv_crash wrote:
| Sounds like DDoS amplification attacks but in RF instead of
| network.
|
| I always find it crazy when the information world leaks back
| into the physical world.
| debian3 wrote:
| https://www.eevblog.com/2023/03/01/eevblog-1532-another-2-8m...
| WorldPeas wrote:
| Reminds me of the old low power stuff from make magazine like the
| joule thief. I wonder how it'd stack up...
| blobbers wrote:
| Are we basically trying to build cold blooded animals? Sit in the
| sun, absorb heat, now they can move.
| tsol wrote:
| Cold blooded animals generally use less energy than warm
| blooded animals because they use environmental heat instead of
| producing their own. So in a way that's one possible method to
| making something more energy efficient
| HPsquared wrote:
| Unlike plants, cold-blooded animals aren't solar powered.
| thangalin wrote:
| I've been looking to swap in a rechargeable battery for a
| 3-Button Mini Remote Control (LiftMaster 890MAX). The remote
| control's case 60 mm x 35 mm, the device pulls 3V at 225mAh, and
| I'd like to replace the 3V CR2023 with an RJD2032C1 rechargeable
| coin cell battery from CDE.
|
| The idea is to affix a thin, lightweight, high-efficiency 3V - 5V
| solar cell to the back of the case that can trickle-charge the
| battery, such as the SM141K06TFV from ANYSOLAR ($10.98, 184 mW,
| 58.6 mA, 4.15 V, 45 mm x 22 mm x 1.5 mm).
|
| Ideally, the remote control would be battery-free, but not having
| to swap the battery more than once a decade would work. Any ideas
| on how to accomplish this?
| Neywiny wrote:
| 3v 225 mAh is not what it pulls. That's the battery rating.
| "Pulls" refers to the current at a voltage. For example, you
| may say that it pulls 100 uA at 3v. So, first step is to
| measure what it actually pulls. Ideally profile it over time
| and in different scenarios. Or record how long it takes to
| drain the battery, measure the battery voltage under a small
| but nonzero load, and approximate how much energy was drained
| vs time to get watts consumed. Then you can work out what kind
| of solar cell and charge controller you can pair it with.
| Unsure if MPPT would be needed here, you likely aren't going
| for the absolute max power efficiency.
| ricardobeat wrote:
| My Samsung TV has this [1]. Maybe you can find a broken/used
| one to repurpose?
|
| [1] https://www.ebay.com/itm/405460571652
| doawoo wrote:
| I love energy harvesting it's one of my favorite topics in
| embedded land.
|
| I've been toying with a chip that harvests power from an NFC
| phone near by and it's super neat to have a microcontroller just
| do its thing with no direct attached power supply.
| mmooss wrote:
| Isn't that effectively wireless power, thus inefficient, and
| not purpose-designed wireless power, thus even even less
| efficient?
|
| It's interesting regardless; I'm just trying to understand some
| of its potential (and maybe these things can be overcome or
| become irrelevant for certain uses).
| doawoo wrote:
| Oh there's almost certainly a ton of loss, that said it's
| definitely still super fun to play with. And makes me excited
| for better advancements in that field.
|
| The chip I'm playing with is the NAC1080 - supposedly
| designed for small lock motors but I'm using it to update an
| eink display on tap
| hr2016 wrote:
| Cool, you just pointed me to a interesting thing! I did not
| know about NFC energy harvesting. I've been thinking about
| a eink project. Thanks!
| teraflop wrote:
| Yeah, there are plenty of use cases for which overall energy
| efficiency doesn't matter, because the actual energy demands
| are so low.
|
| If you can run a microcontroller on a fraction of a milliwatt
| (which is entirely feasible) then it might not matter that
| you're wasting another 10 milliwatts on wireless power
| delivery. Depends what your energy source is.
| mmooss wrote:
| How much ambient power is typically available in different
| environments? I skimmed the article but didn't catch any clear
| information.
|
| Also, if I collect ambient wifi power, for example, instead of
| reflecting wifi - to whatever extent I do that - I create a sort
| of black hole. How does that affect availability of the wifi
| signal for its intended use?
| fuzunoglu wrote:
| https://en.wikipedia.org/wiki/Crystal_radio
| weberer wrote:
| The talk page led me to this video where someone manages to
| light a LED with a crystal radio and a joule thief.
|
| https://www.youtube.com/watch?v=za-mAlrdtkk
| userbinator wrote:
| "New?" Things like RFID tags have been doing so for several
| decades, and prominent companies like Analog and TI have a whole
| range of energy-harvesting ICs.
| brcmthrowaway wrote:
| Can Starlink type phased array technology be used to achieve
| wireless power transmission?
| ben_w wrote:
| Yes but.
|
| The main advantage of a phased array isn't related to
| efficiency, it's that it can be "pointed" a different direction
| purely in software.
|
| The ability to focus electromagnetic radio power from any
| source is: "how many wavelengths across is the antenna?"
|
| This applies to receiving as well as transmitting, which is
| also why radio telescopes need to be physically so much larger
| than optical telescopes, but for beamed power you don't care
| about the receiver's ability to focus, so the size of the
| receiver is determined by the smallest region _the transmitter_
| can focus on.
|
| https://en.wikipedia.org/wiki/Diffraction-limited_system
|
| https://en.wikipedia.org/wiki/Thinned-array_curse
|
| https://en.wikipedia.org/wiki/Radiation_pattern
|
| https://en.wikipedia.org/wiki/Phased_array
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