INDIKATOR shows when it is time to connect your CTEK charger to charge the battery using a traffic light symbol. The device is handy, easy to carry and operate, making it perfect for checking multiple batteries in workshops or showrooms.Traffic light symbols: Red: The battery voltage is below 12.4 V. It is definitely time to recharge the battery. Yellow: The battery voltage is between 12.4 and 12.65 V. It is time to recharge the battery. Green: The battery voltage is above 12.65 V. OK! No need to charge.