The device is constructed of inverter and battery and therefore become a long-term backup UPS, which has imported integrated circuits of modulating pulse width and the newest technique of PWM control. Due to adopting GTR or IGBT power driving components. The device can be automatically voltage stabilized. Softly starting-up and widely used to emergent power supply for electronic apparatus, family appliances, classroom lights, communication equipment computer, automobiles or vessels of hotel, bazaars, entertainment sites. etc.