The UZK24.121 Battery Module utilizes two non-spillable maintenance-free VRLA lead-acid batteries (connected in series), that are assembled in one package with all the required wiring included. The Battery Module is available in two different options. It can be ordered as UZK-module with a battery or as UZO-module without a battery which can be installed at a later date to avoid outdated batteries. The Battery Module also includes a sensor board, which contains a temperature sensor and a center-tap connection terminal. The use of the sensor board enables to monitor and charge the two batteries individually and precisely, which extends the service life of the batteries and makes the use of matched replacement batteries unnecessary. The use of the sensor board is optional, the DC-UPS will also function without the sensor board installed.