If the "resting" battery voltage was as low as 10V, then under load (direction changes or transitions from not-moving-to-moving) the voltage could get that low. Also the roboRIO Driver Station may enter "Brown Out", meaning actuators are disabled to keep the roboRIO running.
https://wpilib.screenstepslive.com/s...anual-id=24166
This is a good opportunity to learn about the Driver Station logger. Take a quick look at the DS logs of last night you can see how low the battery voltage got. Learning how to use the viewer will come in handy at some point in the future if your robot ever misbehaves during a match and you need to figure out why.
https://wpilib.screenstepslive.com/s...og-file-viewer