FOUND BUG: If you take an uncharged vajra and break 1 block with it it will become charged! The same thing applies to Advanced Diamond Drill
Strange, but this bug sometimes happens, sometimes not. If it happens, IC^2 items behave the same way, so it is bug of IC^2.
It's not a bug, if you wearing GraviSuite, BatBox, Lappack, etc all tools will be recharged after use.