While not a must, when I install batteries in a metal container I like to put something non metallic on the walls, even stick on floor tiles, old bits of plywood, whatever, will do. If a wrench comes in contact with wall it can cause the battery to explode.
It is hard and rare to get a battery to explode but if you have ever seen it, you will understand why I NEVER work on a battery without googles, not safety glasses googles! I was watching a friend working on a battery and it just happened, no warning, nothing just boom! He was lucky and not injured.