Hi!
Be very, very careful!
Many tools need more than just +- to run, and they communicate (heat, charging state, shut off, cell protection ...)
I wouldn't attempt this without knowing exactly, that certain safety features still work as intended. Sometimes it's built into the batteries, sometimes the tool ...
Some tools won't run if they can't communicate with the battery and/or identify it.
Again, be very careful playing with lithium ion batteries ...
Just my 2 cents ...
Kind regards,
Oliver