I was given this for a Christmas gift and I love it. I've drilled hundreds of holes to pin and drill out the barrels for my 40k armies and they seem to still do as well as the first day I got them. The drill bit sizes are perfect for most if not all barrels I have come across (Bolters, Shootas, Exhaust pipes, Lasguns, and many more). It is amazing how long it holds a charge. I don't know how to quantify it into something meaningful to you, but I have not had to charge it for drilling out an entiSee full review