In most cases, the unit is past its replacement date; if it is more than 10 years old, it needs to be replaced. The first step is to check the replacement date on the back of the smoke alarm.
However, there are several other factors that can reduce the battery life. A full summary can be found in the operating instructions. Other factors for a weak battery are:
The frequency with which the smoke alarm is triggered: frequent false alarms or test alarms lead to an earlier discharge.
The location of the installation, in particular compliance with the installation instructions according to the operating manual: Excessive temperature fluctuations, e.g. due to environmental influences, lead to reduced battery life.
Networking of smoke alarms via the networking terminal: if several smoke alarms are connected to each other, the battery life can be reduced.
The additional use of modules: The use of additional functions (e.g. KNX signal transmitter) can also lead to a reduction in battery life.
You can find the operating instructions in the online catalogue or download them from the following URL: https://partner.gira.com/data3/23361790_2208_en.pdf
If none of these factors apply to you, contact your local electrician to have the device checked.