A battery system and a method for determining an open circuit fault condition in a battery module are provided. The method includes measuring a first voltage between first and second electrical sense lines while a first transistor in a first cell balancing circuit is turned off, and measuring a second voltage between the first and second electrical sense lines while the first transistor is turned on. The method further includes retrieving a first resistance value from a table stored in a memory device. The method further includes determining a first cell balancing current based on the first and second voltages and the first resistance value. The method further includes determining a first open circuit fault condition between the first battery cell and the first cell balancing circuit if the first cell balancing current is greater than a first threshold current.