A power system and a method for energizing an electrically heated catalyst are provided. The system includes a first battery outputting a first voltage, and a second battery outputting a second voltage. The system further includes a switching device having a first operational state where the first and second batteries are coupled in series to one another, and a second operational state where the first and second batteries are coupled in parallel to one another. The system further includes a generator coupled to the first battery, and when the switching device is in the second operational state the generator supplies a third voltage to the first battery to charge the first and second batteries, and to the electrically heated catalyst such that the catalyst heats exhaust gases upstream of an oxidation catalyst.