Fjgotgame:
Many moons ago, I was in the same boat as you. I saw how cheap the Ultra Fire and Trust Fire were and assumed they'd be safe enough for use in a mech without doing any research. I came dangerously close to injuring myself while (unknowingly) testing the limits.
Thankfully, ECF was there to show me the error of my ways before I ended up in the E.R.
As said above, steer clear of any battery with "fire" in its name. It's foreshadowing right there in the brand name.