LilyGo T5 4.7" - screen not working with battery installed

daern

I have two of these devices running with ESPHome. In both cases the display no longer works with the battery installed, even when powered from USB, although it works fine when powered solely from USB.

The most recent device is only a few days old and has worked perfectly fine up until now when I (very carefully!) removed the protective film from the display using the red tab. The screen is displaying just white, but if the battery is removed (while leaving the USB connection in), the screen refreshes entirely normally.

Because this is my second device, I have obviously been exceptionally careful with it to ensure that I did nothing to damage it, but even so, it seems that it's now in the same state as my first device and no longer working when the battery is inserted. I have tested with two different 18650 batteries and the test battery is 4.05v measured. I have been running the most recent device on battery for the last two days (to measure the expected battery lifetime) and it's been otherwise working fine.

Am I missing a trick here, or is there some specific change that I need to make after removing the protective screen?

Before:

After:

teastain

Sadly I see no one has responded.
If you can find the GitHub repo from LilyGO for this exact board, you could raise an "Issue" and attract help from the factory.
With another board, the T-Display S3, this fault is caused by not initializing the PWR_EN in the setup of your sketch, but I do not know the GPIO output for your board.
On mine it is GPIO15.
Cheers, Terry

Codiak

I am using MPy and have similar behavior to Terry.

Using the initsetup.py logo as a test app as a baseline:
Without battery) It takes ~3 seconds for the LCD to light up and show the logo. I can reliably repeat the unplug/plug-in process and ~3 seconds is a very good estimate...

With battery) there is no indication the device is powered... I plug in the USB, hit the RST button and the log comes up after 3 seconds.  Now when I unplug/ plugin the USB port the LCD is on / off instantly.

The behaviors suggest that the battery alone won't boot the system, nor will it keep the LCD lit but the board itself remains powered.

Definitely need clarity here as to what we should be expecting. Eliminating the need for an external boost power supply is a core feature I am interested.

Also wondering if it's safe to power the board via the 5v port...