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Joined 9 months ago
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Cake day: February 25th, 2024

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  • The article is very misleading. It says

    The research paper…notes that the human body is particularly efficient at generating 40 MHz RF energy. Tapping into that through a ‘worn receiver’ provides power without using any invasive means.

    But I read much of the pdf linked at the bottom of that link, and there’s nothing about the human body generating energy at 40MHz. The trick is that skin is pretty effective (sort of) at conducting energy at that frequency, so the authors hooked up a power transmitter worn on the forearm, 5 or 15cm away from a receiver on the hand.

    This isn’t about powering anything by body energy, it’s about strapping a battery-powered transmitter somewhere on your body and then having another device pick it up when strapped somewhere else on your body. No thanks.

    Oh and it’s actually pretty inefficient and won’t provide much usable energy.





  • That article describes exactly what I would not want to do - subject my expensive vehicle to additional discharge/recharge cycles thereby shortening its battery’s useful life prematurely.

    Lithium batteries are pretty great (except for when they catch fire and are nearly impossible to extinguish), but their performance degrades slightly with every charging cycle. You may have noticed that after a year or two your phone no longer makes it through the day without extra charging, because its total capacity is reduced.

    The same thing happens with EV batteries (translating into shorter driving range) but they’re much larger and more expensive to replace. Moreover, when replaced, the old batteries are still capable of useful work with lower capacity, so it’s excessively wasteful to dump them into the hazardous e-waste stream for whatever passes as recycling.

    There are companies that are collecting those used EV batteries and using them for electric grid storage, which sounds like a great way to extend their lifecycle and to acquire useful equipment at bargain basement prices. That’s what I meant about only ever seeing it at grid-scale. It would be nice if somebody sold a controller for those to be repurposed for use as energy storage for a single home, at much lower equipment cost than a brand new home battery.

    There will be many more used EV batteries available in the next several years as the first wave of widely adopted electric vehicles ages out, and the oversupply should drive down their costs further.

    That said, being able to use a vehicle battery as an emergency backup during a storm event is a wonderful side benefit. It’s just no substitute for a full time home battery (that’s actually connected during the day when the panels are producing, instead of being parked at work away from your house).