TO RECOVER DEAD BATTERY, I HAVE USE TWO TECH.
1. CHARGE BY BENCH DC POWER SUPPLY AT 15 V CURRENT 10-15 % OF AH CAPACITY UNDER CVCC MODE.KEEP FOR SIX HOURS, WHEN IT STOPS TAKING CURRENT.
NOW DISCHARGE IT USING 12 OHM / 20 WATT WIRE WOUND RESISTANCE, UP TO THE VOLTAGE LEVEL GOES 7.5V
REPEAT...
YOU ARE FACING A HARD TROUBLE THERE IS TWO/THREE SOLUTION TO THIS PROBLEM.
1. INCREASING CAPACITY OF UPS. WHICH IS NOT A GOOD
SOLUTION A COSTLY APPROCH.
2. GET UPS SYSTEM WITH STATIC BY PASS HAVING AUTO BY- DIRECTIONAL TRANSFER, IF OVER LOAD IS SENSE LET LOAD BE TRANSFER TO BY PASS D.G. SUPPLY/...