This is not only a charger box for batteries, it is also a power bank for your phone when full charged the batteries. It works with 1 ~ 4 batteries according to your demands.
2 USB ports and 1 charging port, you don't need to worry about your mobile phone / mp3 / tablet... running out of energy anymore. When batteries run out of energy, you can exchange other battery or charge them from PC, laptop, wall charger or car charger.
You can know the total power of your batteries by the LCD display. For example, if the LCD shows ' 25 50 ' , the total power is 25%~50%, ; if the LCD shows ' 25 50 75' , the total power is 50%~75%. You can turn the light on or off by pressing the button beside the LCD screen for 3 seconds.
Make sure the positive and negative directions of the battery are right.