I wrote:
> Ah. With a Prius there is usually some regeneration when you go downhill, > even if you do not press the brake lever. . . . It is a fly-by-wire system > in which speed is regulated by the overall system of ICE plus electric > motor. I do not mean it works like cruise control, which keeps the car at a fixed speed. If you hold the accelerator steady it will slow down going uphill and then speed up going down. But I think you will see regeneration register on the computer display anyway. The accelerator pedal is not a direct, mechanical link to the engine throttle. It is more a suggestion than a command. The computer display showing the battery level and energy flow is here: http://en.wikipedia.org/wiki/File:Prius_mfd_energy.jpg It is not a good idea to watch this display while driving! This particular display shows the car is stopped with the ICE idling and recharging the battery, with no vehicle propulsion. The display indicates that the wheels are not turning. The outdoor temperature is 45 deg F (top right) which is probably why this car is idling. Normally, when the car stops, the ICE shuts down after a few seconds. It stays on in cold weather for the first 3 minutes or so. A person who is used to driving a regular car will accelerate uphill and then slack off going down. When you do this on a long hill the Prius computer shows regeneration, and the battery fills rapidly. Too rapidly. It fills up and the rest of the momentum is lost. That's why a bigger battery saves more energy. Some Prius models also have cruise control. That's a separate feature. The Prius has conventional disk brakes as well as regenerative braking. - Jed
