When it is inserted into the cigar-lighter, there will be the lights to show the status of battery. Red light shows that the battery isdead and can not be used any more. Yellow light shows thebattery is close to death, you'd better change a new one. And there is another three green lights. The more green lights are, the newer the battery is. Accordingly, we can easilyknow and compare the efficiency before and after installing F-16 Pulse King.
