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Motor Current Max Brake

Motor Current Max Brake is a setting in VESC Tool that defines the maximum negative motor current the controller is allowed to apply during braking and regenerative braking.

This setting determines the maximum braking torque that can be produced by the motor. Increasing Motor Current Max Brake increases braking force, while reducing it results in gentler braking.

Like Motor Current Max, this limit applies to motor phase current rather than battery current. Because braking current flows in the opposite direction to acceleration current, Motor Current Max Brake is entered as a negative value.

During regenerative braking, the motor operates as a generator and converts mechanical energy back into electrical energy. The controller regulates Motor Current Max Brake to control how much braking torque is applied.

⚠️ Motor Current Max Brake is not the same as Battery Current Max Regen. Motor Current Max Brake limits the braking current flowing through the motor windings and therefore determines the available braking torque. Battery Current Max Regen limits the amount of regenerative current that can be returned to the battery during braking.

The controller acts as a power converter, so Motor Current Max Brake can often be significantly higher than Battery Current Max Regen. This allows strong braking torque while limiting the charging current seen by the battery.

Motor Current Max Brake should be selected based on:

  • Desired braking performance
  • Motor current rating
  • Motor cooling capability
  • Controller current rating
  • Vehicle traction and stability

Setting Motor Current Max Brake too high can result in:

  • Excessive motor heating
  • Wheel lock-up or loss of traction
  • Over-current faults
  • Controller overheating
  • Unstable vehicle behaviour on low-grip surfaces

Example

A system may be configured in VESC Tool with:

  • Motor Current Max: 180A
  • Motor Current Max Brake: -120A
  • Battery Current Max Regen: -20A

In this example, the controller can apply up to 120A of braking current through the motor to generate braking torque, while limiting the regenerative current returned to the battery to 20A.

⚠️ Strong regenerative braking is also limited by battery voltage, battery charge state, and the configured Battery Voltage Regen Cut-Off Start and Battery Voltage Regen Cut-Off End settings. When the battery is fully charged, regenerative braking may be reduced or disabled to prevent overvoltage.

In simple terms: Motor Current Max Brake is the VESC Tool setting that determines the maximum braking torque the motor can produce during braking and regenerative braking.