I'm new to electronics and I'm making a DIY Bluetooth speaker. The problem I have is with powering the circuit. I plan to use 2 18650 2200mAh 3.7V lithium-ion batteries in series and use an XL6009 step-up converter to boost the 8.4 volts to 12V needed by the TDA7266 Amplifier Board. Also, I'll be using an LM2596 step-down converter for the 5V needed to power the VHM-314 Bluetooth Audio Receiver Board. To charge the 2 18650's, I'm using the HX-2S-A2 BMS module and TP5100 Lithium Battery Charger.

1: Am I doing it right? 2: What kind of adaptor should I use to charge the batteries? 3: Can I use an MDY-03-AF Xiaomi Adaptor to power the circuit and charge the batteries? 4: Do I need any type of Relay in this circuit? 5: How can I automatically stop using the batteries when the adaptor is connected? And here we have my crappy schematics (Sorry!):

Information for the MDY-03-AF Adaptor:

  • Model : MDY-03-AF
  • Quick Charger 2.0
  • Output : DC5V-2A / 9V-1.2A / 12V-1A
  • Input : AC 100-240V, 50/60Hz, 0.5A

1 Answer 1


1: Not entirely by the looks of it

2: 12V 2A adapter typically, but do check the manual of the specific TP5100 module you have, as there must be many different ones made and sold.

3: No, for many reasons. First is that you get only standard 5V out unless you make something that fakes to be a quickcharge module to get 12V out. Even if you manage to do that, it can only output 1A at 12V and it can't give 2A to the charger.

4: Not sure what would you plan to use the relay for.

5: Add some circuitry to change the components to be supplied from charging port, but then the power supply must provide charging current plus the component operating current.

  • \$\begingroup\$ Thank you. I wanted to use the relay to stop the circuit from using the batteries and only use the adaptor. As in this screenshot I've taken from a YouTube video: ibb.co/s15t8S2 \$\endgroup\$ Commented Jan 9, 2021 at 22:27

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