With your controller turned on, paired, and connected to a device, the first LED will be lit by default. This indicates that your controller is the 1st player. The LED only changes when an app changes your player number to the 2nd, 3rd, or 4th.
Checking Battery Charge Level
To check the charge of your battery, power cycle the controller and examine the LED behavior for the first 3-5 seconds before it changes to a single solid LED.
4 LEDs cycling left to right = 0 to 24%
1 LED flashing = 25% to 49%
2 LEDs flashing = 50% to 74%
3 LEDs flashing concurrently = 75% to 99%
4 LEDs flashing concurrently - 100%
Battery Level while charging
With the controller turned off and charging, you will see the LEDs blinking from left to right, each marking a block of a 25% charge (0%-25%, 25%-50%, 50%-75%, 75%-100%). Please note, the LEDs will continue blinking even when your controller is fully charged.