The purpose of this thesis is to study the charging characteristics of ReflexTM for lead-acid batteries. Based on the circuit features of Buck-Boost converters, a positive-pulse charging current is offered to the circuit in the Buck-converter to charge the battery. Then, when the circuit is in the Boost converter, a negative-pulse charging current is offered to ease the chemical reaction of the electrolyte and further to prolong the life time of lead-acid batteries. According to the experiment, on the premise that the negative-pulse charging current is fixed, the larger positive-pulse current will shorten the charging time. The smaller negative-pulse current will likewise lead to the shorter charging time while the positive-pulse charging current is fixed. However, adjusting the low frequency reveals no obvious effects on the charging time.