Battery light remains on

i have an Acer AspireV5-572p Core i5 touch screen laptop. the problem is that the battery light of my laptop remains on and does not turn off even charger is not plugged in and laptop is off. while charging the light color is orange but after unplugging the charger the light turns to be dim red (when laptop is on) but after turning off the laptop when charger is not plugged in, the light once turns off for one second but again turns on. now the color of light is purple.