Wireless Earbuds Charge Themselves

As more and more ports are removed from our smart devices, it seems that we have one of two options available for using peripherals: either buy a dongle to continue to use wired devices, or switch to Bluetooth and deal with perpetually maintaining batteries. If neither of these options suits you, though, there’s a third option available as [befinitiv] shows us in this build where he integrates a tiny solar panel to his earbud case to allow them to automatically charge themselves.

To start, he begins by taking apart the earbud case. For those who still haven’t tried out a set of these, they typically charge only when placed inside of their carrying case, which in his case also contains a small battery itself. Soldering wires directly to the battery allow for the battery to charge without as much electrical loss as he would have had if he had connected to the USB pins on the circuit board. Even then, the cell only generates a single volt so he needs a 5V boost converter to properly charge the battery. That came with its own problem, though, as it wouldn’t fit into the case properly. To solve that issue, he desoldered all of the components and deadbugged them together in order to fit the converter into a much smaller space without having to modify the case in any other way.

With all of that done and the small solar cell attached to the case, [befinitiv] has a smart solution to keep his wireless earbuds topped up without having to carry cables or dongles around every day. We’ve seen plenty of interesting solutions to the problem of various electronics manufacturers removing the ubiquitous 3.5 mm headphone jack too, and not all of them have dealt with this problem without certain other quirks arising as a result.

20 thoughts on “Wireless Earbuds Charge Themselves

  1. Since these always live in my pocket as I walk around, I’d love a kinetic recharge circuit to sip some of my movement energy back into the battery.

    maybe I’ll just steal some of the design ideas out of the failed(and rightfully so) AMPY kinetic charger) and make my own. Ampy was a failed project since they were trying to charge a while phone, but this might work for earbuds that are already designed to be very energy efficient.


  2. Why does anyone even buy a phone without a headphone jack?
    Then again, there are plenty of people willing to fork over $1000+ for a shiny new pocket toy every year. I’ll stick with my $10 LG smartphones. They work just fine, and I don’t get nearly as upset when I drop one and the glass breaks.

    1. Obviously because they have no wires. Also last TWS headset I bought costed me $20 with APT-X and very balanced sound for its price. 3-4h of listening with the battery inside the headset and 2-3 times more if they lay in the case. More than enough for my usecase.

      1. Instead they have batteries that aren’t replaceable so you need to fork out for new earbuds every few years if you want any sort of respectable usage time. Buy a decent seat of wired earphones or whatever takes your fancy, look after them and you’ll still have them in 10 years time.

        1. Unfortunately the shelf life of wired earphones aren’t as long as they used to be either. I find myself replacing them every few years either way and now alternate between wired and wireless depending on activity.

    2. >Why does anyone even buy a phone without a headphone jack?
      Um, perhaps some people just don’t need it at all? I prefer wireless headphones as well, mainly because they have no wires.
      Smartphones that work “just fine” are not enough for some people. I need mine to have a good camera for when I travel or document various electronic stuff. Decent (FHD) screen resolution to comfortably browse web on the go or connect to a remote PC. Agreed, all this doesn’t require a $1000+ phone, but a $10 one won’t cut it either.
      Some people spend their extra money on cars, bikes, clothes or travels, and some do spend it on phones. Whatever makes you happy.

    3. Why does anyone do anything that’s over the top, unnecessary, and pointless (to us normal folk)? Probably because they have the means to and can. To each their own I guess, hell if I had cash to burn I’m sure I’d find an equally seemingly silly way to get rid of it.

    4. I would love a phone with Headphone jack but, the problem is, getting a GOOD modern phone with a headphone jack is kind of hard.

      If your a Apple fan, nope. If your Samsung fan, like me, nope. I have a Note 10+ no headphone jack(got used for $300).

      I did buy a USB-C to Headphone with a good D to A adapter in it. Sounds great and was only like $25. So there is a option. I use my 10 year old $140 Sony mini earphones. I tried some modern Bluetooth ones, they work, just not as good.

      1. Sony Xperia 1 II or III are pretty solid options that are often overlooked for being too niche. The II is reasonably cheap now and is plenty capable. Sounds decent too. They even used to bundle in the decent Sony wireless headphones. Mine came with some meh xiaomi wireless buds. Have yet to try them.

    5. I’ll throw a possible reason here — on my most recent phone, I wanted something that was powerful enough to last for 3 years, minimum. That means having something of a recent vintage, or a couple-year-old high-end phone, so that I could benefit from fast processors, lots of storage space, etc that will stand the test of time. Equally as important to me was the ability to run LineageOS. That limits our options.

      Unfortunately, high-end phones are the ones that don’t have headphone jacks, such as the Pixel 3 I ended up with (for about $200).

      So there ya go, that could be one reason. The built-in headphone jack is a lower priority than the other requirements.

      Side note – the Pixel 3 comes with a USB-C to 3.5mm adapter, which is small and not bulky at all. I just leave it on my wired headphones full time, and it’s basically just part of the cord. So there is a way around the lack of jack. But I still use my wireless earbuds primarily.

    1. Good point, I should have noted that in the video. Couple of points:

      * Yes, the battery has its own protection circuit
      * The Diode drops the maximum voltage to roughly 4.3V
      * The charging current is tiny. Even if the protection circuit does not kick in, I would not expect negative consequences from this.

      In summary: Yes, it is a bit unorthodox but I am confident that my battery will survive this. Time will tell I guess :)

  3. Well, what if it’s not sunny where you are? What if it’s winter? And the solar cell he uses for this project is an abysmal 1V 45mA cell. I’ll leave it as an exercise to the reader on how long it would take to charge a 390mAh typical wireless earbuds case battery (hint: it’s over a week!)

    I think it’s stick with wireless charging

    1. In case on no sun: The USB-C port is still there and functional.

      Regarding the charging time: I think more important than the capacity of the box is actually the time you can use the headphones.

      On a sunny day the cell generates 12mA, the earbuds consume 15mA. So from one hour in the sun you almost get one hour of usage.

  4. That is a fantastic idea. I got a pair of airpod knockoffs for $10 from one of those strip mall phone repair stores, and the case battery was so fried it wouldn’t charge. I got a replacement pair but he let me keep the old broken pair. I will absolutely try this.
    My only concern is that the already tiny earbud batterys would be fried with constant charging? Maybe replace them with supercapacitors?

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