The problem seems to be simple:
There are two adjustments in UPS circuit board.... one for upper battery charging level cutoff ... this is usually set to 14.5volts and the other for lower limit to start bty charging this usually between 9.5-10V.
In simple words when a bty is charged it needs to be disconnected from charging after achieving a certain point ... this is the func of first adjustment.
Similaraly when a UPS operates on bty the bty discharges but it should trip at a certain limit within safe discharge zone ... this is the job of second adjustment.
There is also a third adj in UPS but i don't remember the func right now ... probably it deals with charging time.
All you need to do is to go to a shop which manufactures local UPS and ask for adj of circuit in your UPS. The time available for charging is also critical here.
If still some part of problem exists get your bty checked for its specific grativity which should be 1250-1260.
Total exp should not be more than 100rs.
One last problem which requires change of digital card or IC is a bit complicated and may cost upto 1400-1500rs.
Tried my best to solve your problem ... hope it helps