Odrive S1 Regen Capabilities (Charge Battery)

1

Hi everyone,

We’re working on a project using the ODrive S1 with the goal of capturing regenerative energy during concentric resistance training. We want to charge a battery instead of using a brake resistor during the motor’s regenerative braking phase.

We understand that the R+ and R- terminals are activated via the onboard brake chopper only when the DC bus voltage exceeds a threshold, and that the parameter max_regen_current controls when the brake resistor begins to shunt current.

Here’s what we’ve tried so far:

  • We put the motor in torque control mode, applied negative torque, and spun it manually in the opposite direction.
  • We connected a multimeter across R+ and R-.
  • We also tried setting max_regen_current to a low value (e.g., 1.0) to see if the brake resistor would activate earlier.
  • Result: No voltage or current was detected across the brake resistor terminals in any configuration.

Questions:

  1. Is it possible to redirect regenerative current to charge a battery instead of dumping it to the brake resistor?
  2. Is the brake resistor circuit active only above a fixed voltage threshold (e.g., ~56V)?
  3. Should we be monitoring regenerative current at the DC bus input (V+ / GND) instead?
  4. Is there a way to externally access the regenerated current before the brake chopper kicks in?
  5. Are there known configurations or logs to confirm when the brake chopper engages?

Thanks in advance — really appreciate any help on this!

2

Answered on Discord, putting responses here to help others :slight_smile:

  1. We understand that the R+ and R- terminals are activated via the onboard brake chopper only when the DC bus voltage exceeds a threshold

This is not correct. The brake chopper is immediately commanded to do current as soon as there is regeneration, as long as that current is above max_regen_current , your brake resistor is enabled, and brake_resistance is set. In addition, we send some extra current to the brake port according to the voltage droop curve specified by the DC bus overvoltage ramp

We put the motor in torque control mode, applied negative torque, and spun it manually in the opposite direction.

When you do this, you should expect to see current flowing back to the battery - NOT through the R port.

  1. Is it possible to redirect regenerative current to charge a battery instead of dumping it to the brake resistor?

Yes! Via the DC+/- ports, not the R+/- ports.

  1. Is the brake resistor circuit active only above a fixed voltage threshold (e.g., ~56V)?

No, it’s always active above max_regen_current

  1. is there a way to externally access the regenerated current before the brake chopper kicks in?

The DC+/- port is where current up to max_regen_current will go

  1. Are there known configurations or logs to confirm when the brake chopper engages?

See the values in ODrive.BrakeResistor, such as duty and current. ODrive API Reference — ODrive Documentation 0.6.10 documentation (edited)