How to regulate battery voltage on a UPS?

Question

Uninterruptable power source

The BNT-1000AP UPS has been working properly for many years, but recently I got tired of changing batteries, holding on for a little over a year.
The question is, is it possible to somehow adjust the voltage?
I don’t know much about electronics, so it will be problematic to solder something, but in principle I can try.
On aliexpress, there are a lot of all kinds of voltage regulation toys, for example:
LM317 Adjustable Voltage linear regulator P ...
But I don’t know if these will fit, and how to connect them.

Answer 1

I twisted VR1, it turned out to be working, I set it to 27V (it was 27.8).
I'm closing the topic, I didn't have to add anything else.
Thanks to everyone who participated in the discussion.

Answer 2

And where did you get the idea that the voltage on the battery does not correspond to the norm?
Not
In addition to trying, you also need to understand why and why and what is fraught with.

Answer 3

If you want to understand what's the matter - see my first three questions. If you want to regulate the voltage not for, but in spite of, then a potentiometer will suit you.