The Keithley 2300 series are single or dual channel special power supplies with extremely fast settling times of 10us. They can be used both as a source, as well as a load (sink mode). These devices are mainly used in the production of mobile phones. It supplies the mobile electronics with power, but with the same instrument the charger electronic can be tested. With the new battery simulator model 2281S from Keithley Instruments various batteries like NiCd, NiMh or Lithiumion can be charged or dicharged. Base specifications like "State of Charge" (SOC), "Voltage open circuit" (Voc) or "Equivalent Series Resistance" (ESR) are calculated and visualized in real time on a graphic display. These data can be edited, imported or exported in a .csv file.