A power system includes an inverter, a pair of traction batteries electrically in series, and collectively in parallel with the inverter, a plurality of switches electrically in series, and collectively electrically in parallel with the traction batteries and inverter such that the switches are connected between the traction batteries and inverter, and one or more controllers programmed to operate the switches during charge of one of the traction batteries or operation of the inverter to balance states of charge of the traction batteries.