Arduino Uno every time Reset

Whenever I dump my code and run it through USB power my code works fine but when i remove USB cable and switch on battery power the code doesnt work properly. I need to press the reset button and it works fine. Its tedious every time to press reset.

Please suggest me any possible software reset !!

If it is a good normal battery, it should work. You could add a delay of 500ms or 1000ms at the start of the sketch, to be sure the voltage is stable.

How many cells (volts) in your battery pack? Any large caps on the supply lines? What are your BOD fuses set to? Try adding 1uF of capacitance from reset pin to ground to slow down device coming out of reset.

I used 9v transistor radio battery .I think it provides enough current, should i replace it with any high current rating battery??

Thunderbolt: I used 9v transistor radio battery .I think it provides enough current, should i replace it with any high current rating battery??

Yes.