Fujitsu-Siemens is a Japanese-German company from the IT industry, in which 50% of the shares belong to Fujitsu and the other 50% to Siemens. The company was 10 years on the market, was founded in 1999. In 2009, the 50% Siemens shares were taken over by Fujitsu. The range of the manufacturer includes, among others, the following notebook series: Amilo, Amilo Pro, Esprimo Mobile, LIFEBOOK, CELSIUS Mobile. Each notebook is equipped with a battery regardless of the manufacturer in order to work on battery power. After prolonged use, the performance of the battery may deteriorate, which may affect battery life. In such cases, changing the battery is recommended. The market is now saturated and contains a large number of replicas, but also original batteries. We decided to sell rechargeable batteries from Green Cell. Rechargeable batteries bearing this logo are based on state-of-the-art Green Cell rechargeable cell batteries, which make working comfortable and reliable.