Design and implementation of intelligent Li-ion battery charger

Nowadays, Li-ion batteries are considered the best type of rechargeable batteries due to their high energy density, but they need a specific mode of charging to avoid their explosion. In this thesis, we have designed an intelligent battery charger that charges the Li-ion batteries by a constant current-constant voltage mode based on pic16f876 microcontroller. The charger can charge a variable number of Li-ion batteries that connected in series. The mode of charge has shown to the user by using two LEDs, one refers to the constant current mode and another one for constant voltage mode. The voltage and current are detected in our design in order to make the necessary judgment on charging state of the batteries and also to present the values of charging current and charging voltage to the user in the LCD. Pulse Width Modulation signal was adjusted to obtain high-precision charging control. In addition, the Buck DC-DC converter has been used for producing positive regulated output voltage. The user could adjust the cutoff voltage and the charging current according to the number of series batteries that the user wants to charge. In addition to the cut-off voltage and charge current values, the value of input DC voltage which supplies the circuit also presented to the user on the LCD screen.