Do you mean with brake-pedal only? I can't tell when the exclusively regen braking stops and the calipers kick in. I've not experienced the "notch" that some people report when they suspect regen braking cuts out, leaving only the mechanical brakes to slow the car below about 15 mph. It would not be good for the car to rely solely on the brakes when coming down a long grade because the brakes might overheat, not to mention the excess wear. I believe the Clarity uses the traction motor to generate electricity to provide supplemental regen braking whenever it's time to slow the car down. When the battery is fully charged the system needs to dispose of any regen electricity coming from the traction motor, no matter whether the regen is activated by the minus paddle or the brake pedal. I wish we could find a patent that describes the Clarity's behavior when the battery is fully charged vs the Accord Hybrid/Insight when their batteries are fully charged.