CyberPower’s CP900AVR has an easy-to-use interface with just two buttons (electrical power on/off and mute) and 4 indicator lights (showing once the unit is turned on, once the battery backup kicks in, when AVR is activated, and when there’s an influence overload) within the front on the device. Image: Michael https://beckettmmgbv.blogstival.com/57936115/getting-my-ups-battery-tester-to-work