I purchased this SMT1500C to replace a failing CyberPower UPS and so far it's been great.

Great UPS for a server room with two or three rackmount servers

(Plug & Play!), here New Battery Pack for APC Smart-UPS

120V LCD SMT750 Compatible Replacement by UPSBatteryCenter, and here APC Smart-UPS 750 (SUA750US

All that was required was to have the Powerchute management software installed, and to perform what is termed a "Runtime Calibration" under the Smart-UPS 1500 / Diagnostics menu