for the Gardena-T-1030-1805 model....
Gardena 1030 1805 Operating Instructions Manual Page 7
11. Battery
11.1 Status indicator
If the battery capacity falls below a certain level, a warning signal sounds every 15 seconds. The programs you have set are not run. The water flow cannot be opened manually. If a valve is open, however, it will be closed.
11.2 Changing the battery
If the battery capacity is too low (the warning signal beeps every 15 seconds), you must change the battery.
To do this, the water timer must be removed from the tap.
Important : Changing the battery deletes the data you have set.
To change the battery :
1. Insert the battery in the battery compartment
2. Set the Run Time control knob
3. Reset the watering data as described in "Setting the watering data".
3 If the Run Time knob is not turned to Reset, 5 seconds after the
battery was inserted the current Run Time shall be accepted. This is confirmed by a double beep.
Note : The time the battery was changed is taken to be the starting time.
To ensure that the water timer works properly we recommend that you insert a new battery at the beginning of every gardening season, or at the latest after a year.
Important ! Please dispose of used batteries properly at the appropriate communal waste disposal site. Only dispose of batteries when flat.