I have several of the Skil screwdrivers that use the “36bat” battery pack, but those packs tend to die (stop holding charge) quickly.
These are Nicd or Nimh packs, but they’re also 3.6V, so today, I got curious and started trying to take one of the dead ones apart. I eventually decided that there wasn’t any way to non-destructively take it apart, so after looking at it, I decided to use a hacksaw and just cut around the circumference. The plastic turned out to be fairly thin, and I was able to get it apart:
That is an uprotected 18650 on the left, for comparison.
So there are 3 Nimh or Nicd batteries (~16340 size in series). My thinking is that if I could replace the 3 batteries with an 18650 and maybe some kind of spacer, then I could shove the whole assembly back into the backend of the screwdriver. There is a piece of foam at the backend of the assembly now, to provide pressure, so I could do something similar.
I’m thinking that I’d take the whole thing apart to charge or replace the 18650.
Here’re a couple of more pics:
This one shows how the back piece of the battery holder slides into and locks:
EDIT: A closer view of what the front end of the battery assembly looks like: