With damage ranging from 100 to 200 (or more depending on what distance the enemy infrantry is and what type of vehicle the grenade hits)
The maximum number of grenades you can bring to the battlefield with each respawn depends on how many training points you have in "Frag Grenade" - max is 4.
To equip frag grenades, you must spend at least one Training Point in the Frag Grenade Training located under Training. Once a point is spent, go to your Weapons page, go to inventory, and click and drag the Frag Grenade into an open slot. You will then be able to use on the battlefield.