I asked the guy, he said they use the same methods at all the batteries plus locations. He said the key is using a dead blow, you know the kind that are all plastic, and rattle when you shake them. 1LB and a hard surface to set the item on, Cinder block / Ibeam / concrete floor etc.

Bought one over the weekend at your guys favorite store of high quality (Harbor Freight) and used it to open my Macintosh Portable battery pack. I must say it worked better then any of the other solutions I have used. I would say it worked about 90% how it should have. The other 10% was unintended chips around one of the gold plated terminals, and one corner got a slight vertical crack, with the splitting of the horizontal seam.

I'm thinking I still need to prefect the art