Self-Charging Jacket Eliminates Forgetfulness

Certain parts of the Northern Hemisphere are very, very cold right now. For those of us living in these colder climates, [Aaron] has a simple yet effective hack for keeping your hands warm when you go out for a walk in the brisk cold. He’s wired his jacket up for USB charging so he can make sure his hand warmers are always working.

[Aaron] bought a set of handwarmers that conveniently charge over USB, but he always forgot to actually plug them in once he got home, ensuring that they were always dead. To make his forgetfulness a non-issue, he built the USB charger for the handwarmers into his jacket, but he didn’t just run a wire out of the pocket. The USB charging circuit runs through the coat hanger, using some conductive cloth and steel thread in the inside of the jacket’s shoulders. From there, the cloth makes contact with the metal arms of the hanger and runs out of the hanger to the wall outlet.

This is a great cold-weather hack that might help any forgetful people on the north side of the planet keep warm. You could even use this method to charge batteries used in other wearable electronics. This project is a great reminder that sometimes the best hacks are the simple ones that no one’s thought of yet!

23 thoughts on “Self-Charging Jacket Eliminates Forgetfulness

  1. From what I can see in the image, the USB charger is plugged into the wall and only a USB cable runs through the coat itself.

    The way it’s written make’s it sound like the AC to DC charger is built into the jacket itself and that AC is running through the coat.

    The way it’s written, I was wondering how long it would be before it caught or fire or killed someone.

  2. How efficient is this? I imagine this would surely limit how much power the packs can actually draw and how much power is wasted?

    To be honest, It seems like more hassle than it’s worth.

    “but he didn’t just run a wire out of the pocket” – I would prefer this :/

    1. The main point is the “eliminate forgetfulness” part of it. You would feel sorry if you create a 99.5% efficient charger, and forget to plug it in, and never notices until your hands are freezing. Running around the house searching for the charger is not much fun.

      Even a 10% efficient system is amazing if you can just drop the jacket on the hanger, leave it there overnight, and the batteries are charged in the morning.

      1. Okay, that’s a fair comment.

        Putting aside my personal opinion on the project. I’m still curious from a technical standpoint about how the hanger, stitching etc affect how much power the hand warmers can pull.

        1. I used actual wires instead of conductive thread for the charging leads inside the jacket and the conductive fabric on the shoulders has extremely low resistance so the devices connected to the pocket are likely charging at full power (I measured up to 2 watts). The resistance between the usb plug that goes into the wall wart to the usb plug inside the pocket is lower than I can measure with my multimeter. I left it plugged in charging a huge battery for nearly an entire day and all the contacts and components remained cool to the touch. I built this to charge while my jacket is hung up in my office though so even if it were only 10% efficient as thoriumbr hypothesized it would still be enough to have my hand warmer topped up for my walk home at the end of the day. :]

  3. He could have made it inductive charging and not require a special hanger but instead just be places in the right spot eliminating a hanger that has a cable coming off of it.

    Maybe for Version 2.0! Plus that will give you the ability to add an inductive pad in the car seat so when driving it also will charge the jacket’s gadgets.

      1. Just checked it out. While I like the idea of wireless / induction charging. It still doesn’t seem that useful unless your device natively supports induction charging or you buy a special case with the induction charging built in.

        If you look at their example video, she still had to plug a cable into her phone.

        1. Inductive charging is also far more wastful/slower and it’s pretty finicky about being lined up properly. I experimented with inductive charging for this project before settling on conductive pads inside the shoulders. Though the technology is cool I found that this project was better kept as simple as possible.

        2. I tend to have one of those battery packs in my bag, just for those times when I’ve forgotten to charge my phone or my kindle, and I usually put my bag down in the same few places. I only need to top up the battery after I’ve used it. So I think it could work for me.

  4. A coat fit for the weather and some good gloves is all that is needed here. Layers too. Your white shirts are going to get stained as bio takes it course. Unless you can go platinum, there will be rusting with sweat.
    You can’t drop a coat on to a hanger, they take two hands. A chair or back or hook will do.

      1. There are special ‘wireless charging’ cases you can buy for your phone. Usually you get the wireless charger which plugs into the wall and then the case has the coil and circuitry built in and shims into the phones charging port.

        Most of these use the wireless inductive charging that we’ve come to love. But some of them have two metal pins on the back of the case which then sit on two metal plates on the charger. So sure enough, they’re “wireless” but they’re not contact-less.

        So it’s a similar idea :)

        But if you put the conductive threads on the wheels, how will you get the power back to your battery? Won’t you need some brushes or something because the wheels are turning.. ?

          1. Here I thought you were gonna say “just use [inductive] wireless charging!” to which I’d say “I ain’t got those sitting around in my parts-bin.” That’s pretty funny about the “wireless” chargers.
            I’ve had luck conducting through the gear-box and shaft of some motors, for other purposes… Brushes needn’t be highly-sophisticated, maybe a brush riding on the wheel itself. It’s not like we’re trying to transfer serial data; a few interruptions here and there are no biggie.

  5. I’m kind of new with dyi electronics, but what happens if you hang up the coat on the hanger the wrong direction? Won’t it be a problem with swapping the +5vdc with the ground? Did you build a bridge rectifier into the line?

    1. Yeah, I was thinking of that. This would be a good place to place a full-wave bridge rectifier. That would take care of polarity reversal. Although, with the curved, wooden hanger that that [Aaron] used, which has a definite back, would help to prevent that.

      The only trouble with that is the voltage drop over the diodes, that may lower the charging voltage by too much.

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