Mi Band 4 clamp charger

thingiverse

Hi, do you like new sport tracker bracelet Mi Band 4 by Xiaomi like me? It's a nice piece of tech but one thing that I hate is the ergonomics of charging. Finally, Xiaomi has placed charging pins on the bottom of the MiBand for the new generation, but the original charging cradle still requires removing the MiBand from the strap for charging. Why did Xiaomi do this? So I decided to design a clamp charger solution without needing to remove the MiBand from the strap. And here is the result. ### Material: To make the clamp, you'll need some flexible material like ABS or maybe PETG (I haven't tested it). For the cradle with the bottom cover, any material will do (I used common PLA). ### Rest of Components: The USB cable and pins can be obtained by disassembling the original charging cradle. To do this, just remove the top rubber cover and carefully pry out the part with two small holes for the pins. You'll need to cut off the USB cable because Xiaomi uses some resilient glue to secure it, so there's no other solution than cutting it off. Finally, take out the board with the pins. ### How to Assemble the Clamp Charger: Print out all the parts and check if they fit together. The clamp holes might require some fine-tuning of the holes on the clamp (this depends on the material you selected for the clamp and cradle). After a successful test, disassemble the cradle and clamp. Prepare the end of the USB cable for soldering and thread it through the cradle, checking the orientation and soldering the cable to the pin board (the red wire goes to the V contact and the gold one to the G contact). Bend the cable and arrange the board into the cradle. Put the part with two pin holes into the cradle, put the clamp onto the two pegs at the bottom of the cradle. You might need to slightly remove the isolation of the cable so that the bottom cover fits into place. For better resilience, you can glue all the parts together, and this will be necessary for the bottom cover at least. **TIP:** After soldering and before putting everything together, you can check the connection between the USB and pins with a multimeter by connecting the cable to a power bank (just to make sure) and checking the right polarity on the pins. The black probe of the multimeter goes to the pin marked as G and the red one to the pin marked as V (the marks are on the bottom of the pin board), and the value displayed should be positive (around 5 volts). I hope you'll enjoy my solution. Feel free to remix it and improve it. https://www.tinkercad.com/things/9OXj37ffjWn-mi-band-4-clamp-charger-v11