Joy-it DSO138-MINI - Connecting an External Battery Unit; Battery Unit Requirements; Connecting Battery to Mainboard; Battery Power Control

The DSO138-Mini can also be powered by a 3.7 V lithium-ion battery as an
alternative to the power supply via the micro USB connector.
Attention! An external battery unit must either be charged externally or a
JYE118 module must also be installed. Aer that, internal charging is also
possible.
First, open your device as described in Chapter 5 - Opening the device.
Aer you have separated the mainboard from the display unit and removed
it from the housing, you can now connect a battery to the mainboard.
The housing can then be reassembled. The voltage supply via the connected
battery unit can now be controlled from the side via the "Bat-Switch".
6. CONNECTING AN EXTERNAL BATTERY UNIT