CyberPower’s CP900AVR has a fairly easy-to-use interface with just two buttons (power on/off and mute) and four indicator lights (displaying once the unit is turned on, once the battery backup kicks in, when AVR is activated, and when there’s an influence overload) around the entrance on the device. Picture: Michael https://knox46vv0.blogstival.com/57937333/getting-my-ups-battery-tester-to-work