The 4 lights on top indicate the battery status. They will light up when you press the round black button once and when you charge your Power+ via the grid.
4 Green LEDs = 75-100%, 3 green LEDs = 50-75%, 2 green LEDs = 25-50%, 1 green LED = (<)25%.
If the battery status shows only one light, it could be that your Power+ doesn’t have enough power to charge your phone. However you can still use the flashlight function perfectly fine!
The single light on the top of your device can tell you if your Power+ is charging from the sun. A singular blink means that your WakaWaka is charging slowly (but surely), two consecutive blinks means it is charging faster already and thrice means it is charging optimally. If this light blinks 8 times in a row when in the sun, it means that it is fully charged. That’s good news because you can now charge your devices most efficiently!
The blue light next to the USB port shows if your Power+ is charging your device. When you disconnect your device the blue light will blink a couple of times.