I refuse to buy cordless powertools. I know it's not exactly the same as built-in batteries, but In their short existence, I have already seen proprietary rechargeable batteries become discontinued (My mom wanted to get an extra battery for a handheld vacuum, couldn't find the battery by itself, so bought what she thought was the same model; nope, they changed the battery design, even though the rest of the new vacuum was the same as the old one)