Does this mower have a clutch & transmission like a car? Or is it a CV thing like my snowblower?
Even if it had a 10 speed transmission, a speed controller might still be
a good thing to have. Especially if you want to limit max RPMs & Amps etc.
A direct connection to the battery sounds like a way to pop a wheelie,
all the way over backwards.. Especially if the batt pack/driver CG was set rearwards.
Not hard to pop one with a gas mower..
YouTube - Poulan lawn tractor pop-a-wheelie
YouTube - MY DAD DECIDES TO POP A WHEELIE ON THE LAWN MOWER....