01/04/2018 at 16:08 •
A few hours past until we noticed the LED colors from the right side were different from the left ones.
The LEDs are on the back side of the modules and indicate if the LiPo battery (if one is connected) is charging (red) or fully charged (green).
It looked a bit too strange to just be something random.
We were trying to find out what was causing this color change, when @davedarko helped us realize that it could be caused by the different power supplies we were using.
We used two 7-port USB hubs to power all 14 boards. The left side was using the original 5V 2A power supply of the hub, while the right ones were using a USB cable connected to a 2.4A charger (the original power supply broke weeks before).
We now think that the USB hub does not support that much current over the USB connection, because that is usually just for transmitting data and you got a seperate connector for supplying power.
That may caused a low voltage output on the USB connections (below 4.2V) and the boards to think that they have to charge their batteries.
But there were no batteries connected and even if there were, why would the power supply voltage matter since the batteries have a different voltage(?)...