You did the right thing and it wasn’t cheap. You need to check your battery each year as it loses 10-15% of storage for every year in use.
The telephone companies have a program of replacing their battery backup every 5-7 years no matter what, as the loss of storage diminishes exponentially after the 5th year.
A regular desulfation program can at least double the life of lead acid cells. I don't expect the phone company to do that but I do. And I have reconditioned swapped out UPS cells and use them. Three AGM batteries in their 11th year now with me.
Surprisingly, it was! The UPS was a throwaway at work--the battery had lost its ability to keep a charge, so they tossed it. I took the itty bitty battery out, soldered some heavy-gauge leads to the original battery terminals, and brought them out to another 12V gel-cell. I got the gel-cell surplus at a ham radio swapfest.
You need to check your battery each year as it loses 10-15% of storage for every year in use. The telephone companies have a program of replacing their battery backup every 5-7 years no matter what, as the loss of storage diminishes exponentially after the 5th year.
Yeah, I've already experienced this. I put the system together 4 years ago, and discovered during a power outage last year that it didn't keep the 'net on very long. So I replaced the gel-cell with a bigger one. Another throw-away at work: terminals were damaged, so they couldn't ship it in a customer device. But it works just fine for me.