Thats the one thing that im worried about is if i start to run it to low. I have the newest Brushless esc from novak i dont know if it has a voltage cut off. i heard about a battery i think its made by scorpion or something and it has the built in cut off but its really really expensive. As for the metal box, when ever i charge my batteries i chuck them in a small tool box that i made at school. ill check and see my esc has a cut off