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Motor Current Max

Motor Current Max is a setting in VESC Tool that defines the maximum positive motor current the controller is allowed to apply to the motor during acceleration and driving.

This setting is one of the primary factors that determines the amount of torque a motor can produce. Increasing Motor Current Max increases the available motor torque, while reducing it limits acceleration and motor force.

Unlike Battery Current Max, which limits the current drawn from the battery, Motor Current Max limits the current flowing through the motor windings. As a result, Motor Current Max is often significantly higher than Battery Current Max.

In VESC controllers, motor current is regulated directly by the FOC or BLDC control algorithm to achieve the requested torque output.

⚠️ Motor Current Max is not the same as Battery Current Max. Motor current determines motor torque, while battery current determines the power drawn from the battery. Because a motor controller acts as a DC-to-AC power converter, motor current can be considerably higher than battery current, especially at lower motor speeds.

Motor Current Max should be selected based on:

  • Motor current rating
  • Motor cooling capability
  • Controller current rating
  • Application requirements
  • Desired acceleration and torque

Setting Motor Current Max too high can result in:

  • Excessive motor heating
  • Reduced motor lifespan
  • Over-current faults
  • Controller overheating
  • Demagnetisation of motor magnets in extreme cases

Example

A system may be configured in VESC Tool with:

  • Battery Current Max: 60A
  • Motor Current Max: 180A

Even though the battery is only supplying 60A, the controller can regulate up to 180A of motor phase current to produce higher torque at lower speeds.

⚠️ Motor Current Max is a normal operating limit, not a hardware protection limit. If the controller exceeds the Absolute Maximum Current (ABS Max Current) threshold, an over-current fault will be triggered to protect the hardware.

In simple terms: Motor Current Max is the VESC Tool setting that determines the maximum torque-producing current that can be delivered to the motor during normal operation.