The HBT144 timer has a built-in rechargeable battery for buffering in case of power failure. This battery must be charged for at least half an hour when used for the first time (or after long-term storage) by plugging the timer into the mains. Then press the RESET button on the back of the device in the nameplate. This will erase all data and restart the program sequence in a defined way. The time starts to run at 0:00 o'clock and must now be set.