We all know the percentages on these devices are just a random number generator; however, since the red LED indicator is linked to a specific percentage, the device will display a low battery LED even when the battery still has more than 3.6V, in my case. This could also affect the usability because I noticed that my Cubexx refused to boot up when it reached 0%, unless I plugged it in, even when it still had several hours of battery left.
This is why I think we should link the LED reading to voltage instead, like when the battery hits 3.1 or 3.2v, the LED indicator turns on. This will make low battery less of a guess.