A system and method of dynamically charging a lead-acid battery that has been in a deep discharged state for an extended period of time or is deeply sulfated includes an alternating current (AC) line input connected to a transformer. The output of the transformer is connected to a pair of silicon-controlled rectifiers (SCRs). The SCRs are in turn connected to terminals of a lead-acid battery. A pair of signal diodes is used to obtain waveform information for the AC input for phase control to trigger the SCRs. The outputs of the signal diodes and the SCRs are connected to a phase regulated output controller. A turn-on time for the SCRs is delayed to create a differential voltage between the transformer output and a voltage of the battery. The differential voltage is applied to terminals of the battery at an increased frequency rate to break battery sulfation.