[ronto]

The battery/alternator/starter test was done with engine ON and than A/C full ON and with all headlights ON and again turn OFF A/c and headlights though the test was only for about a 2/3 mins

I will check back at store if they can do load/capacity test.

Time being i was considering to buy portable jumper starter [ if the battery dies down ] until i know the exact problem.

The battery is still under warranty so will have to convince the store that the battery is the problem to have them give me replacement but at present they say the battery is fine

-Thanks

Let them prove "the battery is fine" by giving you another battery. If the problem disappears the original battery is "not fine". If all the connections are good, the problem you describe IS the battery.