Interesting, I saw few reviews where possibility of this mod was mentioned but not implemented. Andonstar product range seems to be very similar but with different features enabled hardware or firmware wise. For example, AD206 has video output port, but that seems to be disabled in FW.
I also use AD206 (pretty good value for money, image quality and usability are fine. Remote is recommended). I use it with USB battery pack when needed - thus microscope is very portable and has long battery life. Disappearing date does not bother me too much.
I have few questions on the mod. What is voltage level on USB bus with battery only? Do all the lights work (1 lens light and 2 stand lights)? Did you measure standby power consumption?
As the mod is only for the microscope, only the lens light is working.
But I think it is possible to use the battery voltage to power the 2 stand lights, as there are only 2 leds, with a Mosfet and a tiny MCU controlling (PWM) these leds in the original wired-remote.
Standby power consumption, I forget to check that !
So, on my Siglent SPD3303X-E cross-flashed to SPD3303X, it shows only 0.001A on the screen, so I have put my U1272A on µA range: it draws really only 611,7µA !
That's why when I unplug the 18650 battery, and then plugged it back after a few minutes, the date/clock are good (I have to correct the minutes shifting only).
It really draws a very very small amount of current on standby
Also, after putting back the battery, the microscope must be started once with the USB port, I think for getting the battery status at cold start.
After that, no problem starting with battery (with the 3-5s power button push
=> until "welcome" message on screen in fact)
I have not checked for HDMI output (I have not teardown the camera board), but my board is a AD205 from 2020-09.
Also there's a jack port, but don't know what for.
Edit: I have just checked the battery voltage too:
>> 4,25~4,01V: 3/3 battery bar
>> 4,00~3,81V: 2/3 battery bar
>> 3,80~3,76V: 1/3 battery bar
At 3,75V: 0/3 battery bar + big blue Popup on screen "Low battery" then shuts down completly.