I have mostly cyberpower ups's. It always seems a hassle to replace batteries. Unplug all devices, I used to take the ups to the garage work bench, perhaps your wife will allow you to do it on the kitchen table :O and remove the battery access cover, slide the batteries out, disconnect and reverse. So what I did was, [my example below requiring 2 batteries at a time] was just extend the wiring from inside about 2 feet of heavy gauge wire, put on connectors and built a container and connected the 2 batteries in series. This way is much easier to change, measure the voltage on them, keep clients plugged in etc. I used the same 12 v battery but bought some with higher amp hour rating. Some ups's only require 1 battery. Only do this if you are comfortable with this kind of work. YMMV