UPS-Systems are now standard equipment in supplying uninterrupted energy to servers and other IT units. These systems are mainly used in critical areas such as hospitals, computer centers, signal boxes, etc. The power supply in such systems is mostly provided by rechargeable batteries with a voltage of 12V and different capacities depending on the system and its functionalities. Lead accumulators are used, which are divided into 5-year, 10-year and 12+ year batteries according to their lifetime. The batteries are the most important and most sensitive component of a UPS system and must therefore be checked at defined intervals.