Current

In any electric circuit - whether it's an electric bicycle, scooter, etc, it's useful to know how much power the gizmo is consuming, especially when it's running off a battery pack. On battery powered vehicles you need to know the voltage sag under load, and how much power has been consumed. That's to avoid taking the battery voltage too low, and to avoid over-discharging the battery pack. Your riding range, the distance you can travel, is determined by how low you take the battery pack.