USB Won't Connect When Battery is Plugged In

Development Boards ESP32
1

I have a WRL-24408 SparkFun Thing Plus - ESP32-S3. If I don’t connect a battery to the board’s battery connector, the board is detected by Windows as COM3 when it is plugged into the computer.

However, if I connect a battery, Windows does not see the board. Nor does the charge light illuminate.

I noticed that the programming resistor for the charge controller is set to 2k, corresponding to 500 mA. Could it be that the inrush current when connecting the device is too high and it is shutting down the port?

Thanks,
Michael

2

With the battery unplugged from the board, measure its open-circuit voltage. Typical single-cell LiPo should be approximately 3.7–4.2 V. If it’s very low (<2.5 V), the charger may behave differently or draw high current.

1 Like
3

Battery measures 4.15V. It is a brand new battery. I found that if I plug in the USB first and then the battery, the system works and the battery charges. I let it charge for several hours. Still the same behavior.

Thanks,
Michael

4

Can you share a photo of the wiring to/from the battery? I’m worried the polarity might not match

5

Polarity is fine. If I plug in the battery and not the USB, the device runs fine. Also, the fuel gauge chip indicates the battery is discharging.. If I then plug in the USB, it fails to connect to Windows, does not appear in Device Manager, and the charge circuit indicator light remains dark.

If I plug in just the USB, it enumerates under Windows and I can program the device. If I then plug in the battery, the USB connection remains good, the battery charger light illuminates and the fuel gauge indicates that the battery is charging.

The battery is almost fully charged.

Thanks
Michael

6

I should also mention that if I start with battery plugged in and then plug in the USB, the device still runs fine even though it does not connect.