Battery Current Max

Battery Current Max is a setting in VESC Tool that defines the maximum current the controller is allowed to draw from the battery during acceleration and driving.

This setting primarily determines how much electrical power can be supplied by the battery to the motor controller. Increasing Battery Current Max allows the system to deliver more power, while reducing it limits power consumption and battery load.

⚠️ Battery Current Max is not the same as Motor Current Max. Battery Current Max limits the current drawn from the battery, while Motor Current Max limits the torque-producing current flowing through the motor. Particularly at low speeds, motor current can be several times higher than battery current.

Battery Current Max should be selected based on:

• Battery discharge rating
• Battery chemistry
• Cell configuration
• BMS current limits
• Wiring and connector ratings
• Number of controllers connected to the battery
• Desired vehicle performance

⚠️ Battery Current Max should never exceed the continuous current rating of the battery system. This includes the battery cells, BMS, wiring, connectors, fuses, and any other components carrying battery current.

⚠️ When multiple controllers share the same battery, the combined Battery Current Max values should not exceed the battery system limits. For example, if a battery and BMS are rated for 100A continuous discharge and two controllers are connected to the same battery, each controller might be configured with a Battery Current Max of 50A. The exact distribution can vary, but the total current available to all controllers should remain within the limits of the battery system.

Setting Battery Current Max too high can result in:

• Excessive battery heating
• Excessive voltage sag
• BMS overcurrent faults
• Reduced battery lifespan
• Connector or wiring overheating
• Battery damage in severe cases

Example

A system may be configured in VESC Tool with:

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

In this example, the battery will never be required to supply more than 60A, while the controller can regulate up to 180A of motor current to produce torque at lower motor speeds.

In simple terms: Battery Current Max determines the maximum current that can be drawn from the battery during normal operation.