How long can the sander UPSTG500 last after power failure?

I suggest you change to a UPS, and directly lead the direct current of the battery to your cat from the inside, which saves the process of step-up and step-down rectification of the inverter, which improves the efficiency itself a lot and of course prolongs the service life. If it is a 6-amp-hour battery, it is no problem to use it for dozens of hours.