Ok so last night the car was jerking and batterypack was at 7.76v

This morning i charged the battery for a few was 8.12v when I pulled it.
I put it in the car and it ran good once up the living room and back but then the jerking happened again....You can hold down throttle or reverse and it just studders moves a couple inchs...stops...moves...stops....etc.
.
Pulled batterypack and it read 7.85v
It didnt feel warm in any of the cells.

Checked esc connections and they were solid.
Really frustrated right now as this was my boys bday present and he couldnt wait.

It mentions setting a failsafe in the manual but doesnt explain why or what its for....is this the low volt cutoff?