TC32V and TC15 series of timer switches do not have battery back up. Hence after an interruption of power supply, the timer has to be set to the correct time. Part numbers in the TC32V series are TC32V1, TC32V24 and TC32V7D. Part numbers in the TC15 series are TC15/24, TC15/15/24 and TC15/15/7D. For further information, please refer to the attached installation instruction