This is a good article on using power tool batteries for ebikes https://www.electricbike.com/cordles...ies-for-ebike/

I have a BBS01 250w set to 18a current and it's OK for getting up hills with pedalling, and I use it for commuting to work, towing a trailer, and running errands. I would prefer the 20% wider stator on the BBS02 for the extra hill climbing torque and you can get a 36v version, but the BBS01 works OK.

Regardless of which version you choose, you might like to consider spending a little more getting the following items:
- chainring adapter and 42t chainring from Luna, I found the 46t chainring that came with the kit was too high for my gearing.
- gearsensor to cut the power while shifting gear, I tried the big green button kill switch but prefer the inline sensor as its one less thing to think about - if you try to fit it yourself I recommend using a new brake cable as a frayed end simply won't pull through the tight sensor, but you can just pedal backwards to cut the power before shifting.
- the ebrake levers that came with my kit were very cheap and nasty and bent quickly, so rather than replace them I went back to using my old brake levers using magnet sensors (attach the tiny magnet with gorilla glue and/or floral wire because if it falls off the handle the motor cuts out completely unless you unplug the brake from the wiring), the sensor works on my mechanical rim brake levers.