Battery back up nearly Hossed me!!!!

Don't take for granted that because batterys are swollen they still dont hold a charge. While tearing down some rack mount apc backups I recieved a good shock when pulling the wires off the battery terminals. This one had ten small lead acid batts that were all swollen in the housing. Not thinking they could still still have a charge I grabbed the red lead wire with my pliers and zappo....saw the flash before I felt the current. Pliers went across the shop and a mouthfull of expletives soon followed.
I grabbed the wire near the terminal and must have grabbed a bare part as well. **** things have been sitting for two weeks and took for granted they were all shot.



After I found my pliers and had a smoke i started to laugh. I realized I was leaning on a stack of these backups that were up to my waste as I was working on the top one, zipper on the metal housing. ALMOST HOSSED myself!!!!