Custom Coil Lets Mouse Charge Without Wires

It’s 2021, shouldn’t all of our devices be able to pull the power they need from the ether? [Sasa Karanovic] certainly thinks so, which is why he recently took it upon himself to add wireless charging capabilities to his desktop computer peripherals. The Qi transmitter and receiver modules are relatively cheap and easy to come by, the trick is in getting them installed.

The keyboard gets non-invasive Qi charging.

For the keyboard, [Sasa] took the path of least resistance. The receiver coil lives inside a little 3D printed box attached to the back, and power is routed through a hacked up right-angle USB cable. It’s a simple addition that doesn’t make any permanent changes to the keyboard; perfect for those who don’t want to risk toasting their gear.

But that wasn’t really an option for the mouse. Obviously the Qi hardware would have to go on the inside, but at a glance it was clear there wasn’t enough room to mount the stock coil. So [Sasa] pulled the original coil apart and rewound it around a small 3D printed jig. This resulting coil was perfectly sized to fit inside the flat area on the left side of the mouse with no apparent degradation in charging ability. Wiring the module up to an unpopulated pad on the PCB allowed him to easily inject the 5 V output into the device’s existing charging circuitry.

We’ve seen plenty of aftermarket Qi charging coils take up permanent residence in various gadgets, but rewinding the coil is a neat trick that we’ve only seen pulled off a couple times in the past. Something to file away mentally should you ever want to wirelessly power up one of your projects.

22 thoughts on “Custom Coil Lets Mouse Charge Without Wires

    1. Basically it comes down to the coupling between you TX and RX coil. If one is significantly larger than the other, then you will either have a bad coupling or no coupling at all. But as far as I’ve seen, most chargers have a similar size coils and greater size is achieved by adding multiple smaller coils.

      For me, ideal solution was to have two coils and mark their position on the table, so whenever I leave mouse/keyboard at that spot, it’s being charged.

    1. It actually is avalible as a feature on a couple high-end gaming mice that I know of, the Corsair Dark Core SE and a couple of Logitech’s G-series wireless ones have a propriitary version installed.

  1. Why didn’t I think of that? It seems too obvious that a device that spends most of it’s life sitting on pad, which could be powered (and even is, in LED gaming mouse pads), should be wirelessly powered/charged by the pad.

    1. I’m actually embarrassed how long it took me to finally say “There is no point in wireless mouse and keyboard if I still have to keep rats nest of wires to charge them”. The ones in the video have a reasonable battery life, but I also have a high performance mouse and mechanical keyboard, their batteries last couple of days, so this hack increased their “usability” by a lot. :)

      You could also use the same hack to charge your wireless headphones or “any other wireless device”* that uses 5V USB for charging.

  2. I really need this for my logi craft(usb-c) and MX 2S (micro usb) to cut down on ‘cable clutter’ whats the point of a wireless mouse and keyboard if you still need to charge it with a cable!!

    Just need to find* a desk with wireless charging across the whole desk.

    *annoy the wife by buying all the parts and building a new office desk in the garage.

    1. Maybe start by adding a coil to one/two spots that are directly below the area where you leave your mouse and keyboard to charge?

      Now I basically have a “habit” of just pushing my mouse and keyboard to the edges of the mouse pad before I go to bed and they start charging. I don’t do it every night, obviously, but the battery hasn’t died on me since. :)

      Let me know if you come up with a wireless charging across the whole desk solution, I might want to annoy the wife too. :D :P

  3. I recently ordered a bunch of different Wireless / Inductive QI charging receivers from banggood, aliexpress and ebay to try. They were all around $3 each. Some as low as $1.50, some as high as $5. Three of them have arrived so far and they all work with the cheap IKEA 5W charger I bought just to try it out. Going to be hard to get even just the charger IC and coil from a parts supplier at those prices in small quantities.

    This kind of thing should be an easy retrofit. I have a long list of project ideas centred around it.

  4. My cheap old M705 Logitech mouse used for at least 12-16 hours a day works for 1.5 year on a simple charge when using two Tesco NiMH AAs and almost 3 years on 2 alkaline non-rechargeable AAs.

    If your mouse need recharging more than once per year there is something wrong.

    1. No there is nothing wrong with the mouse.
      Your M705 is slow to react, does not updates at proper rates, does not tracks well, snaps corners, does not pack features which requires more energy, etc etc.
      The MX master in OPs video can run “up to 70 days” on a single charge btw.
      I have a wireless gaming mouse (logitech G series), which can only run for ~6-7 days on two AA alkaline in performance mode. But it does not go to sleep, I don’t have to wiggle it just to wake it up. It does not misses the first millimeters or button presses if I move it/press the buttons after being idle for hours. It updates at 500Hz, not 25-50Hz like the old M series mice. It has a latency of less than 2ms, not 40ms (or seconds if it was idle) like the M series. Etc, etc. I even use it with a two 200mah AAA cell sometimes instead of two AA just to save ~50g. This means that it only runs for about two to three hours in “performance” mode and maybe 1,5 day in “eco” mode (where it does switches to sleep after being idle for a few minute).

      Your M705 and the MX Master is in a different league. M705 (and similar) is for “casual” use or for people who does not notice at all anything what I written above.
      Hey, there is even one person in the comments above who said that he does not uses mouse pads. It would annoy me if my mouse would make a scratching sound when I drag it, or it it would not slide (almost glide) half a meter after a gentle toss due to how low the coefficient of friction is.
      Some people does not care at all, they are happy with their laggy, sticky mouses. They don’t even notice it.

      1. Ok gamer.
        “Hey, there is even one person in the comments above who said that he does not uses mouse pads.”
        ๐Ÿ˜‚ I haven’t used one since 1999. I thought they were just for ball mice for the ball to have actually more friction.

        1. Though some optical mice of the late 20th early 21st were a bit picky about surfaces, and didn’t optically track well on very smooth featureless surfaces. It’s still an occasional problem, when you find just the wrong color or reflectivity.

          I get all the mousepads I need for free… cereal boxes or similar. Unprinted side of the box tracks great and you can get a “new” one as soon as it gets grubby. One large or two regular per side of the box. I have tried many pads in the past, and I have not found one that tracks as consistently and smoothly as the back of cereal box cardboard. Well okay, there’s some that are good a couple of weeks, but never as good again with a little wear, no matter how carefully you clean them. If performance of your cardboard mat declines, swap it out. Fresh mat feeling weekly or fortnightly or monthly depending how hard you are on them. There is one limited exception to the general excellence of this solution, Harvest Crunch cereal, some mice don’t like their cardboard, IDK if it’s too shiny or what. Anyway, I bet if you give this a try you’ll never pay money for another mouse pad.

        2. Ok grandpa.
          Who said I’m a gamer? I should be a gamer to like properly working and precise peripherals? One needs to be a gamer to hate shitty mice while doing CAD work? Or to have a proper teflon coated feet on my mouse and an etched glass (or aluminum) mouse pad so I can pixel precise place objects where I want, and not have to deal with sticky movement? The last thing I want to be frustrated by is sub par peripherals while doing productive work.
          But I guess most people are happy with a rough rock surface and a 1$ mouse.

          1. If you think you need a mouse that updates at 500Hz, then yes, you are 100% no doubt a gullible gamer. You also need RGB LEDs for the extra advantage to overcome your opponents. Anything else would be soooo lame. We’re all very impressed with your 1337 mouse.

      2. I’m definitely in the not even noticing it group, but then my MX Master 1st gen with a near-permanently attached cable does everything required of it by my work. It’s only when gaming that it could be better and that doesn’t pay the bills. Fancy mice are in my opinion a hobby item for most people.

  5. A friend of mine added wireless charging to his multimeter. It was a fancy Uni-T model with a rechargeable battery, but it was also IP-rated, so the charger connected through the test lead jacks (occupying all four, IIRC) so as to avoid breaking the seal. He found that inconvenient because he wanted to use the meter while it was plugged in, so he took two voice coils from the head actuators of two identical hard drives and used those to make a wireless charging system, with the transmitting coil in a backpack that clipped onto the back of the meter. I don’t think it was compatible with the Qi standardโ€”I think he just found the resonant frequency of the coils and ran it at that frequency.

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