I recently got a keon, and had seen @hell1337 's great post about modding them for wall power. Here’s the link, I recommend you give it a look over and read. He did a good job documenting the process and the end product works, but it was a bit dated, and I dislike fixed dangling power cables, so I decided to have a go modernizing the design. My keon now has a USB C socket that you can plug into any laptop or other charger that supports the 20v spec. (anything over 65w should probably have it, but never hurts to check, though the device just wont power up if it cant get enough voltage)
This process is a bit more technical than his, but it should be fairly approachable to anyone comfortable using a soldering iron, and it could be adapted quite easily to almost any device that needs a power supply.
To do this, you’ll need 2 main parts, and an optional 3rd, if like me you don’t want to just thread a cable through the case and leave it permanently attached.
- A USB-C PD 20v module ~$2.5 each.
- A DC-DC Buck converter good for a couple amps and 20v ~1.5$ each
- (optional): A 90 degree USB-C adapter to provide something you can glue and secure to the chassis so that you can plug in the external power cable. Otherwise, just have a suitably long USB-C cable that is rated for USB-C PD that you will embed into the case.
Additionally, you’ll need a few bits of wire capable of handling a couple amps. You could cannibalize an old micro USB charging cable, or an old wall wart that doesn’t go to anything anymore, or you might be able to get enough spare wire when cutting off the battery, supposedly the system only pulls a bit over 1.5A so almost any wire will do. compare whatever you find to the metal core of the battery wires if you are unsure. mine came from trimming a bit off an old barrel jack plug.
If you do hobby electronics you might have some or all of these lying around (I had everything but the usb pd module), and any functional equivalent will do, but if you don’t have any local stores that sell these sorts of things, amazon can hook you up, but they only sell in bulk. If you leave the battery in place, the buck converter I used is about the max size you can fit, but if you remove the battery all together, you have plenty of room to fit in whatever you want.
https://www.amazon.com/LM2596-Converter-3-0-40V-1-5-35V-Supply/dp/B08NV3JCBC?th=1 is a 5 pack of buck converters,
https://www.amazon.com/dp/B0953HKPWG?th=1 is a 6 pack of 20v usb pd modules. Almost any 90 degree adapter will work, as long as it says its good for usb pd, or mentions laptop charging etc, and is a flat bend, hamburger style, not one that rotates the plug 90 degrees on its axis (otherwise the parts wont fit inside the case when you go to put it all back together).
I used https://www.amazon.com/Degree-Female-Adapter-JSAUX-Extender/dp/B0B77CJD7T, just because its what I had on hand.
For tools, you’ll need: - A soldering iron and solder
- Wire cutters,
- A box knife helps a ton with stripping the small wires
- a hot glue gun
- a drill and a bit roughly the thickness of your USB plug (or if you are desperate, tinfoil wrapped around your soldering iron and some good ventilation outside. I’ve been there, done that, but don’t recommend it)
- Something to pry the case open. Precision flathead, butter knife, spudger, take your pick.
- depending on your buck converter of choice, you’ll need something to adjust it, usually a tiny flat or plus head to turn the adjustment screw. The one I used was flathead, and a fingernail might suffice if be a bit of a pain.
- A Voltmeter, really any cheap digital multimeter will do. This is for calibrating our buck converter.
Once you have all your tools and parts, we can begin the surgery.
Step 1: Pop the case.
A precision flathead, butter knife, spudger or other prying implement of choice should allow you to get the case off in fairly short order. Start with one side, popping the hooks outward as @hell1337 suggests, then do the other side. with both sets of hooks free, the case should slide directly away from the back of the device. Don’t loose the top two buttons. They are a royal pain and seem to go flying off at the slightest provocation.
Step 2: Disconnect the battery.
I left the battery in, partially because I had been planning on installing a switch but didn’t have room, and because it seemed to be glued in fairly firmly, and I didn’t feel like prying it out if I didn’t need to. I left a couple centimeters of wire on the battery side so that I could tuck them out of the way and hot glue the ends to prevent them touching anything. Cut them one at a time, and if you use wire cutters, there shouldn’t be much risk of a short as the insulation is fairly thick and covers the cut ends mostly. Hot glue or electrical tape to wrap them and stick them towards the edge of the case out of the way will do the rest. Or remove the battery and add a bit of foam like @hell1337 did.
Step 3: The new power supply.
Plug in your USB C module and check the output pads with your multimeter. you should see 20v. If not, check your charger, make sure it supports the 20v spec, otherwise you might only get 12,9,or 5 volts (however much it can put out). If your charger should be able to do 20, it might be your module that is bad, occasionally they get mislabeled (they are all pretty much the exact same parts and board) and you ended up with the wrong ones, or simply a defective part. try the others if you got a pack, and try and get a replacement.
Unplug the module now.
Solder short leads of wires between the USB C module and the buck converter IN side. Just match the + to the + and - to the -.
With the two components connected, plug in a USB C cable to the module and power it up. Put the multimeter on the buck converter OUT pads, and adjust the voltage to 16.5V. Usually, its some sort of screw. For me counter clockwise was reducing the voltage, and I had to do it quite a bit before seeing results, as presumably it had been set for something like 30v default.
Nominally, the battery should float around ~16.8V when fully topped off and not under load, so I set mine just a bit under as a safety margin. For comparison, it probably ends up somewhere around 12.0-12.8V when empty, though the keon might have to shut off before that if the motor needs a certain voltage to work right.
Unplug the module now.
With our voltage set, we can solder the old battery leads onto the buck converter. red to OUT+ and black to OUT-. Plug it back in and try powering on the keon to make sure you have everything solidly connected. If it does, great. otherwise, check the wires and make sure nothing is loose, then check and make sure you have all the +'s and -'s matched correctly.
Step 4: The plug/cable
We can now turn a USB C connection into keon power, but we still need a way to get that connection from the outside through the case and into the keon. If you are just using a cable, you can drill through almost anywhere that has a bit of air gap inside the case and just squeeze the cable into position by folding it. but for the 90 degree adapter, it had to line up just right for the other components to lay flat and fit in the space next to the battery.
Marking off my eyeball estimates on a piece of paper inside the case, I got, from the bottom 6.75 inches, from the battery side case edge 2.125 inches. I then drilled a hole in the case and abused the drill as a crude dremel. Not generally recommended, but using the base of the bit’s cutting edge near the drill, and against the relatively soft and thin plastic of the case, it works without needing to put too much torque on the bit. I kept adjusting the hole until the adapter fit through straight.
A generous beading of hot glue around the hole and under the adapter before pressing it in secured it in place. Just make sure your module can still be plugged in and out on the inside, so it cant be too flush with the inner curve of the case.
If you are just using a cable, I still recommend a bead of hot glue on the hole to serve as strain relief, and make sure you don’t accidentally tug on the guts while using the device or plugging it in.
Step 5: Reassembly.
Almost done. Plug in your module to either the adapter or case cable, so that the outer shell is now connected to the main device. Now comes the fun part. Dealing with the blasted buttons again. It took me a few tries and chasing the buttons across the floor as they fell out while trying to put the case back on before I succeeded. Also, I made sure I plugged in the module so that the flat circuit board side of the buck converter was towards the shell and the tall caps poked inward because that fit better. The way I finally got to work in reassembly was to have the case on the floor, like a U shaped bowl, with the buttons in place, then I lowered the device into it, keeping the sides even (don’t do one set of hooks first and try and wrap it around). Once the device is fully down and the buttons are in position and held in place, the hooks should also be able to be pressed back into their sockets on both sides.
Step 6: Enjoy
Congratulations, you now have a wall or battery bank powered keon for the modern age. I wasn’t able to fit my switch to allow using the internal battery as well as external power, but any USB C battery bank rated for 20v output and >30W should also be able to power the keon, as we used a standard compliant pd module.
Hopefully I did as good a job explaining the process as my predecessor, and this can help others who want to mod their device but didn’t know what was possible.
Have Fun.