Drill batteries for an electric mountain board
Electric drill motors are geared down to give high torque at relatively low speeds.
You don't give a specification for your motors.  But it looks like they draw tens of amps (for example one listed on Amazon draws 24 to 65A.  Four battery packs wired in series/parallel only gives 36V 6AH.
Your batteries are only going to last a few minutes at that current, as they will be grossly overloaded.  There's also a risk they will overheat and catch fire.