I've been looking at tearing out my fiberglass shower, installing Kerdi, and re-tiling the whole thing. During my research into this project, I've come across quite a few forums that have members typing in all caps about not mixing thinset with a cordless drill because the motor will burn out. Is this true? Even for small batches? My shower is only 3' W x 3' D x 6' H.
I've got an older DeWalt 14.4V drill that's on it's way to retirement (its batteries aren't holding a charge well), as well as a new Milwaukee M12 lithium ion 12V drill and an M12 Fuel 1/4" impact driver. Is one of those sufficient or should I go buy a cheap HF corded drill or check Craigslist to add to my growing collection of tools-that-rotate-things?