Using 18v 4 ah drill battery on skateboard

Could you guys answer my question. I’m looking to build a single belt drive longboard using a 6384 200kv motor with a flipsky mini vesc. The thing is i live in Australia and li-on batteries are expensive and LiPo batteries are annoying. I have a couple 18v 4 ah Ryobi batteries lying around and i was wondering if they would work if i put 2 in series. I’m concerned about the discharge rate though.

There have been a (very)few who have gone down this route.

I was thinking of doing the same thing. I kinda blew up my battery and am desperate to ride😁