Should the UPS output be exactly same in normal and battery backup modes ? Of course the AC line power from the electrical utility is true sinusoidal with an accurate frequency of 50 or 60 Hertz. The typical (standby and line-interactive) UPS will pass through the line power when in normal mode. Typically only a high-quality UPS will output true sinusoidal AC power when in battery mode. A UPS ...
The VA rating tells you about the maximum load you can put on the UPS, and this can also be a very loose proxy for the quality of the components - because higher rated UPS's will typically have componentry and cooling which can support higher currents and are thus more robust.
Why are UPS battery backups all rated in VA instead of AH?
This CyberPower news article says: higher end workstations and computer systems that incorporate Active Power Factor Correction (PFC) power supplies may unexpectedly shut down or crash entirely when used with a simulated sine wave UPS. CyberPower use the term, PFC Sinewave, and APC (APC 1500VA/900W UPS ) uses the term Sinewave UPS.
As long as I have the tracking number, the UPS Track API works great. I use it as described on the help page:
UPS REST API - Tracking vs Track by Reference - Stack Overflow
If a UPS lasts long enough, the cost of replacement batteries overruns the initial cost. If you are buying quality UPSes, therefore, give more consideration to the running cost of the UPS than to the initial purchase price.⁶ A midrange UPS from the same manufacturer costs about ⅓ that of a true-sine UPS with the same headline specs.