USB Power for Battery Powered Tchibo Coffee Mill

The battery powered coffee grinder from Tchibo is a great little helper if you like to grind your own coffee and want a compact grinder. However, the batteries show some degradation over time and will not last for more than one load of beans before you need to recharge.

Replacing the batteries would be one solution to the problem. As we always use the grinder at home, adding a possibility to use a USB-PD power supply instead, seemed a better option. The grinder happens to have enough interior space available to add a USB-PD module.

With this modification, it will still operate on the rechargeable battery, but will also run on the additionally installed USB port on the breakout board. I have not added a switch, so it will operate as soon as a proper USB power supply is connected.

Tchibo battery powered coffee grinder 

USB-C PD (power delivery) breakout board, 32x20 mm. This one is not branded but sold by various sellers on Amazon.

3D-printer, screwdriver, drill

I designed an insert for the grinder to fit snugly inside and hold the breakout board in an upright position. I printed it on my Creality K1C with a 0.4 mm nozzle and standard settings (0.24 mm layer height) for "generic PLA", using black PLA for it.

On other printers, the dimensions possibly need to be adjusted as the print sits tight in the grinder.

About a hand wide worth of red and black wire gets soldered accordingly to positive and negative terminals on the breakout board and the motor.

The breakout board is set to request 9 V from the USB power supply.

This is propably the trickiest part...

I used a 4 mm drill and a few small files. I got the first hole wrong, so I now have one spare :-)

The insert fits tightly in between the lower right post and the upper corner of the motor´s gear box. The breakout board sits firmly in it with only little play.

Re-attach the lid which should allow access to the USB-port if the hole for it was made properly.