The portable device serves for uninterruptible power supply of 24VDC consumers at available AC-net using the built in rectifier unit or from external supply unit this could be a fuel cell of maximum voltage of 28,8V. If AC-net is not available or in mobile missions, the power supply is assured by the integrated gel battery set of 24V 16Ah. The device is classified IP54. The batteries are mounted shock resistant. The EMC classification fulfills minimum CE. During the charging the display shows current and voltage and external load. In case of a failure charging beep sounds, which can be acknowledged by pressing the button. If no network or external supply is available, the display shows battery condition BATT. OK (> 21.6V), BATT. SPACE ( 20.4V) or OFF (<20.4V) by pressing the button. The power cable is connected to the device firm. The consumers can be connected by a customized cable. Caused by the integrated conservation of the charge the power supply can be arbitrarily long operated on the network. The battery charging is temperature compensated. The output voltage can be switched by a rotary switch. Recharging is required every 6 months.