Sir battery is INVA TUBLAR 245MM hight 19 spin 7.3mm tube and 7plates but question is that how to calculate the backup of any battery either  tublar or flat plates 

Sh. Ranbir Chakraborthy says that More information are required to answer this question. All details are not given. Back up based on 400W load ? It is also not mentioned as flat positive or tubular. Back up depends on AM content too. Normally IT range is with Tubular. If 73 mm is width of cell then 8.1 mm tube can be used. Which gives higher Back up.