CyberPower’s CP900AVR has a fairly easy-to-use interface with just two buttons (ability on/off and mute) and 4 indicator lights (demonstrating in the event the device is turned on, if the battery backup kicks in, when AVR is activated, and when there’s an influence overload) about the front in the unit. https://lipe05814.blogdemls.com/36229983/5-simple-statements-about-ups-battery-tester-explained