Battery is one of the media for power supplies in electronic devices. However, the battery�s ability supplied power limited on how big the capacity that is stored in batteries. When the battery charge runs out, it needs re-charging (charge), where the device to recharge the battery charge must consider several aspects such as charging current, battery voltage and when the charging process must be stopped, this is considering that batteries for electric bicycles 3x12V/12 ah has a maximum current limit charging 3 A, and with charger in the sales package, not allowed to charge more than five hours. The fact is, many owners of electric bicycles do excessive charging so the battery does not last long. The solution to this problem is to use battery charger, which can be used to charge the battery charge to some voltage rating (12V and 24 V). This battery charger is equipped with buckboost converter for voltage and charging current regulator which way this works is based on the large PWM duty cycle generated by the microcontrolle
