XIAO Overheating when using usb power and battery power

Hello,

I noticed that if I hook up 3v (2 packs in parallel of 2 double A batteries wired in series) and also hook up the USB line my XIAO gets really hot and one of the LEDs will blink rapidly. I have to unplug everything and wait a bit before using it again. I have the battery + wired to 5V and the battery - wired to gnd. Is this configuration not supported? Or have I likely done something wrong? I also noticed that if I hook up a serial line to TX and RX, and connect the ground of the serial adapter to the XIAO the board powers on. I feel like this shouldn’t happen. :confused:

Any guidance would be greatly appreciated.

Hi
@kkirbatski Are you connecting two batteries in parallel and connecting the positive and negative poles to the power pin of xiao’s GPIO and ground pin? If you use the GPIO pin to power it up, voltage input connected to general I/O pins may cause chip damage if it’ higher than 3.3V.

Hi, if you know, it is possible to connect a 3.7v Lipo battery to the 5v of the seeeduino and connect at the same time a cable to the usb port to program it without disconnect the battery?

This will not affect, you can connect to the computer while connected to the power source.

If connect a 3.7V Lipo battery to the 5V pin of XIAO and connect XIAO to USB, isn’t it dangerous because a Lipo battery is charged from USB 5V without current limit?

It is not dangerous*******************

According to the circuit diagram, it will be connected to
VBUS(USB 5V) ----> D4 ----> 5Vpin ----> 3.7V Lipo.
Isn’t it overcharged even if VBUS (USB 5V) is directly connected to the 3.7V Lipo battery?

edit:
According to the USB standard, the power supply voltage range is up to 5.25V.
The voltage drop of diode D4 is Typ 480 mV in the data sheet.
The 3.7V Lipo, which is generally considered to be charged at 4.4V, is charged at 4.77V. Is this okay?

If this is the case, you need to connect a power management module between the lithium battery and XIAO to prevent the overcharge of the lithium battery from damaging XIAO.