Hi folks, thanks for this thread. Since no one has mentioned ESP32S3 boards yet in this discussion, I’ll add that my experience is identical to @chipko. When plugged into USB with a battery attached, the charging light blinks and the program runs. But when unplugged, the program halts and does not run, even after manual restarting. This is the sample Arduino Blink program, which does not include any use of Serial.begin(). I have 3 other boards that all work with this same program and same battery. I think some boards might just be faulty.