Help Safely Disabling Brake Resistor and Configs

Hi All,

I would like to remove the brake resistor as we’re using a battery bank and wanting to confirm the safest procedure and settings. I’m putting my understanding based on the ODrive documentation and various posts below but would love a confirmation. Thanks!

To start I am following the Startup Guides’ advice on estimating max braking power required:

When braking at max speed and with maximum motor current, the power that is dissipated in the power resistor can be calulated as: P_brake = V_emf * I_motor where V_emf = motor_rpm / motor_kv.

In our case, we are estimating max brake power of 60A at 900RPM with the D6374 @ 150kv where P-brake would == 360W if I’m doing my math right. Not really a major issue for us with a 48ah battery @24V that would be something like a 15A regen (0.3 C charge rate) if it was completely instantaneous.

So after confirming that the brake power can be absorbed by the battery bank I’m looking at the available config values:

  brake_resistor_armed = True (bool)
  brake_resistor_saturated = False (bool)

  max_regen_current = 0.0 (float)
  brake_resistance = 2.0 (float)
  dc_bus_undervoltage_trip_level = 8.0 (float)
  dc_bus_overvoltage_trip_level = 59.92000198364258 (float)
  enable_dc_bus_overvoltage_ramp = False (bool)
  dc_bus_overvoltage_ramp_start = 59.92000198364258 (float)
  dc_bus_overvoltage_ramp_end = 59.92000198364258 (float)
  dc_max_positive_current = inf (float)
  dc_max_negative_current = -9.999999974752427e-07 (float)

Based on a few posts the only information I can find is that odrv0.config.brake_resistance should be set to zero. Which I have done and removed the resistor, all seems fine enough. I’m leaving brake_resistor_armed = True (bool) alone as I’m not sure it really matters with the value set to zero.

That said, my intuition was to change a few more of these configs and is confirmed by a couple posts including this and this.

// Set Max Regen to Max Battery Recharge , 0.5C Charge Rate
max_regen_current = 24 (float)

// Leaving undervoltage trip alone
dc_bus_undervoltage_trip_level = 8.0 (float)

// Setting Over Voltage to Max Recharge Voltage From Battery Manufacturer
dc_bus_overvoltage_trip_level = 30 (float)

// Setting Max Negative Current to (-1 * Max Regen Current)
dc_max_negative_current = -24 (float)

That’s it, this appears to be functional and looking forward to any others’ insight.


Looks fine to me. Was waiting for someone to do this. Later when you use devel, you can set emable_brake_resistor = false instead of using 0.0 for resistance

Awesome thanks @Wetmelon! Out of curiosity, is there a current workflow to promote topics to the getting started guide or docs? I’ve been running into a few things lately like this that seem to be documented piece meal in the forum but not declared officially in the docs.

You can edit them yourself and generate a pull request: