Tool battery powerpacks are usually just literal 18650's chained together. I have a chainsaw one that's actually just a buncha nicads. They don't do replacements. I am not paying another couple hundred for a useful tool that I use once in a blue moon. I know you can get replacement battery packs, but are there small, dodgy shops where they will perform the swap for you?
(I want a battery upgrade which will also need new charger but I am not fuckin' soldering lithiums)
nah, they don't tend to do tool batteries. There's one not far from me in mentone - I've recycled a UPS there, gotten a new battery for my 2009 ebook...not so much on the tool front.