I vaguely recall seeing someone modify their UPS for this in their "homelab", such that they were running a 12v cable modem, router and WAP off of the UPS batte

I vaguely recall seeing someone modify their UPS for this in their "homelab", such that they were running a 12v cable modem, router and WAP off of the UPS battery pack directly somehow. They had dramatically longer run time from a full charge. (Well more than double, I think.)