Abstract: A charging system for charging a battery is disclosed. The charging system includes a first light emitting diode (LED), a second LED, a power conversion module, and a charge control module. The charge-controlling module includes a controlling unit and a comparator electrically connected to the power conversion module. When a voltage of the battery is lower than or equal to a critical voltage, the controlling unit illuminates the first LED. When the voltage of the battery is greater than the critical voltage, the controlling unit illuminates the second LED. When the voltage of the battery is lower than or equal to a regulation voltage, the comparator makes the power conversion module to charge the battery with a constant current, and when the voltage of the battery is greater than the regelation voltage, the controlling unit makes the power conversion module to charge the battery with a constant voltage.