Mi Band 4 Clamp Charger

Hi,
do you like new sport tracker bracelet Mi Band 4 by Xiaomi like me? It's nice piece of tech but one thing which I hate the ergonomics of charging. Finally Xiaomi for new generation placed charging pins from the bottom of MiBand but the original charging cradle still require removing MiBand from the strap for charging. Why Xiaomi, why? So I decided to design clamp charger solution without need of removing MiBand from the strap. And here is the result.

• printed printable parts or 3D printer and materials bellow
  • ABS or PET-G for clamp
  • anything for cradle holder and bottom cover (I used common PLA)
• sharp knife
• soldering iron
• glue

For the clamp you need some flexible material like ABS or maybe PETG (not tested). And for the cradle with bottom cover does't matter which material you choose (I used common PLA)

The USB cable and pins (pogo pins) you can get by disassembling original charging cradle. To do it just remove top rubber cover and carefully pry out part with two small holes for pins. You must cut off USB cable because Xiaomi fasten cable with some resilient glue so there is no another solution than cut it off. At last take out board with pins.

• Try if printed parts fit together. Clamp holes maybe will need some fine-tuning of holes on clamp (it depends on the material you selected for the clamp and cradle and their thermal expansion).
• After successful check disassemble cradle and clamp.
• Prepare end of USB cable for soldering and thread through cradle
• check orientation and solder the cable to the pin board (red wire to V contact and gold one to G contact)
• bend cable and arrange board into the cradle.
• put clamp to the two peg at the bottom of the cradle. Maybe you will slightly need remove isolation of the cable so that the bottom cover fits into place
• put part with two pin holes to the cradle
• For better resilient you can glue up all parts together, you will need to do this for the bottom cover at least.

TIP: after soldering and before putting together, you can check connection between USB and pins with multimeter just connect cable to power-bank (just for sure) and check right polarity on the pins. Black probe of multimeter put to the pin marked as G and red one to the pin marked as V (marks are on the bottom of the pin board) and the value displayed should be positive (something around 5 volts).

Just try it :-)

I hope that you will enjoy my solution. Fell free to remix it and improve it.
https://www.tinkercad.com/things/9OXj37ffjWn-mi-band-4-clamp-charger-v11https://www.thingiverse.com/thing:3802158