Can not find or calculate ampere hour from the data sheet
Using the information from the spec. sheets 17 &amp; 18, and 80KW as an example, you would use 80 (28Ah 12v) batteries.  That would be 1KW per battery.  You should be able to draw 80A from the 28Ah battery, for (28 X 60)/80 = 20 minutes.  Taking inefficiencies into account, it might just be 15 minutes.  Obviously, if you want it to last longer or draw more current, you need to add more batteries in parallel.  Keep in mind that UPS are intended to provide power so that systems can continue operating only for a few minutes until main power returns or emergency power is activated, not as a continuous source of power. 

EDIT:  In case you need a more realistic answer, you would need about 25 batteries to provide 500A for 1hr, 100 batteries would last you 4 hrs.