sparkles
Well-Known Member
- Thread starter
- #1
TLDR: The R1 regenerates a significant amount of energy when using ACC to control speed, so I believe it does use regenerative braking despite the brake pedal moving upon slow down.
Background: Since the R1 was launched, owners have observed that the brake pedal moves as the car slows when using ACC or Driver+, and it’s been oft repeated that the system is using the friction brakes to slow down to the detriment of efficiency due to not using regenerative braking. On a recent drive I observed that although the brake pedal was moving as the car slowed on ACC, the brake lights on the R1 model on the driver display were not illuminating, the same as if you were gently slowing using regenerative braking. I thought the addition of the new energy tab and it’s regenerated energy readout might let me do a little experiment.
Testing: There is a steep street near my house in San Diego that has a 230 ft elevation change in less than 0.5 miles distance. I did 6 runs down the street at 40mph, which requires constant braking force to maintain. I did 2 runs each with the iterations being manual speed control with regen set to “High”, Rivian ACC set to 40 mph, and the added test of using my Comma 3X with speed set to 39mph, which indicates 40mph on the Rivian driver display.
Conclusion: In all 6 test runs, regardless of controlling speed with manual regen, Rivian ACC, or the Comma 3X speed control, I regenerated 0.4 kWh of energy on the downhill test. This leads me to believe that the ACC is in fact using regenerative braking. Why the brake pedal moves as you slow? I have no idea, my theory would be some sort of preemptive “pre-charging” of the brake system to decrease stopping distance in a panic stop situation. I would love to get an official answer from Rivian about this.
Background: Since the R1 was launched, owners have observed that the brake pedal moves as the car slows when using ACC or Driver+, and it’s been oft repeated that the system is using the friction brakes to slow down to the detriment of efficiency due to not using regenerative braking. On a recent drive I observed that although the brake pedal was moving as the car slowed on ACC, the brake lights on the R1 model on the driver display were not illuminating, the same as if you were gently slowing using regenerative braking. I thought the addition of the new energy tab and it’s regenerated energy readout might let me do a little experiment.
Testing: There is a steep street near my house in San Diego that has a 230 ft elevation change in less than 0.5 miles distance. I did 6 runs down the street at 40mph, which requires constant braking force to maintain. I did 2 runs each with the iterations being manual speed control with regen set to “High”, Rivian ACC set to 40 mph, and the added test of using my Comma 3X with speed set to 39mph, which indicates 40mph on the Rivian driver display.
Conclusion: In all 6 test runs, regardless of controlling speed with manual regen, Rivian ACC, or the Comma 3X speed control, I regenerated 0.4 kWh of energy on the downhill test. This leads me to believe that the ACC is in fact using regenerative braking. Why the brake pedal moves as you slow? I have no idea, my theory would be some sort of preemptive “pre-charging” of the brake system to decrease stopping distance in a panic stop situation. I would love to get an official answer from Rivian about this.
Sponsored
