A Variable Duty Cycle Pulse Train Charger for Improving Lead-Acid Battery Performance

This study focuses on the design and implementation of a variable duty cycle pulse train charging (VDCPTC) strategy aimed mainly to reduce the detrimental effects of sulfation in order prolong battery life. This paper proposes a pulse train type of charging unique from that of conventional pulse charging. A burst of pulses at 1 kHz frequency is injected in the battery via a 345W/57.6V Half Bridge LLC resonant converter. The pulse train charger was designed and implemented with a microcontroller that controls a switch turning on and off producing the charge pulses to the battery. The experiment is done through 3 sets of partially sulfated batteries subjected to charge and discharge cycles. Results show improvements in the discharge performance after tests. The discharge time improvement shows that the charge carrying capability of the battery has improved under pulse train charging. The discharge performance improvement is consistent with the battery impedance findings. Internal battery impedance after pulse train charging is reduced to a third from its original value. A 10% charging time improvement is observed compared to conventional CC-CV charger.