The battery doesn't 'use' power. The battery produces the power that all the other electrical devices use.
If the starter motor is using 2,520 watts, then the battery is producing energy at the rate of 2,520 watts. That means 2,520 Joules of energy every second.
Thanks for giving us the formula.
E = P x t
Energy = Power x Time
Energy = (2,520 watts) x (1 second)
Energy = 2,520 Joules