A starter battery with a total battery voltage exceeding a supply voltage requirement of an electrical system. An alternator provides a charging voltage that corresponds with the supply voltage requirement of the electrical system. A total battery voltage equal to the sum of cell voltages exceeds the supply voltage requirement of the electrical system. A step-down voltage regulator reduces the total battery voltage to correspond with the supply voltage requirement and a boost voltage regulator increases the charging voltage from the alternator when charging the starter battery to the total battery voltage. When detecting a degraded cell, the step-down voltage regulator continues to regulate the total battery voltage to correspond with the supply voltage requirement after the cell has degraded and the boost voltage regulator is bypassed when charging the starter battery to no longer increase the charging voltage from the alternator when charging the starter battery.