I am pretty sure they are sealed batteries in your ups. I could be
wrong though.

The state-of-the-art lead-acid battery is the valve-regulated type
(sometimes called "sealed" or maintenance-free), which fixes the acid
electrolyte in a gel or in an absorptive fiberglass mat. The advantage
of this design is that the battery needs no water additions, can be
operated in any position, and can be used in close proximity to people
and sensitive equipment. Additional benefits: maintenance-free,sealed
no-leak design, higher cranking amps, lower self-discharge, greater
vibration resistance, heavy duty, no-corrosion terminals.