Under Hood NHRA Battery Hold Down

My car was done by a friend, who is a Super Stock racer. He way overkill the whole thing by, putting a reinforcement plate under the floor. Took 1/2 threaded rod up thru that plate and used a piece of 1 x 2 tubing, with angle iron welded to it, for the battery clamp. I have little doubt that the entire car could be lifted by the battery boxes.