Second Life for Xiaomi Power Bank

This PCB will replace original controller board from Xiaomi power bank in case it become damaged or malfunction. In my case some components pads become oxidazed after water was spelt and durring attemping to clean the board - one 0402 resistor was lost.

Source files of PCB are available on GitHub - you will find there gerbers, drills, bill of materials and assembly drawing files.

• Order the board from PCB manufacurer (I used JLCPCB service). Durring ordering - upload gerber & drill files and choose 1 mm board thikness.
• Order the components. There are no special components on PCB, all of them are general purpose.
• Solder the components. A high-density footprints are used for compoents on a PCB. Recomend to use solder paste with dispenser and heat gun soldering station for easyer work.
• Check board on shorts. Especially battery pads.
• Unsolder battery pins with solder iron and solder onto new PCB. Make sure that battery during resoldering process is not overheated.
• Test the charging and discharging ports with USB tester. Done!

Some notes:

• Button, LEDs and connectors can be taken from original board. Before any manipulation with original board - unsolder the battery. Make sure that components are not damaged. In my case Micro USB connector also was with oxidated contacts, due to this current durring charging did not exceed 0.7A@5V. After connector was replaced by new one - charging current become 2.2A@9.1V.
• The original NTC sensor that is measuring battery voltage during charge in discharge cycles is 10 kOhm. It need to be replaced by NTC temperature sensor with 100 kOhm value. In case you won’t use NTC sensor - just replace R5 with 51 kOhm.

Here is short video of power bank operation.