[Canadian Prius]

(Posted in 'Technical' section also)

I have searched this site and others to get a better understanding of regenerative braking. The best I have been able to find is the attached diagram from Toyota showing the improvement for 2004, but I would like to know how efficient the system is, how much of the kinetic energy it re-captures, and how much braking is done by the generator/motor vs the brake pads. Does anyone know?

 

[RSnyder]

Well, Toyota claimed up to 33% of energy recovered by regenerative braking on the 2001-03 Prius and the chart shows the 2004 does better, so maybe it's now up to 50% :?:

I haven't seen any advertised claims for this model though. Also "up to" means it's also possible (likely) to be less in most "real world" braking situations.

 

[Canadian Prius]

One way to test the energy in the battery is to drive in reverse because the ICE can't help out. I live on a steep hill, part of it very steep, and the rest just a little less so. My elevation is about 340 feet, and the hill climbs about 200 feet. With a full battery I can climb it in reverse quite fast, but it does take the battery from full, (7 bars) down to about four bars. Then when I coast down the hill again, it goes only up to five bars. This is no kind of scientific test, but it does tell me that there is a lot of power there, to raise the car 200 feet in a minute or so.

I am fascinated by the possibility that the only energy necessary for travel might one day be just enough to overcome rolling resistance and wind resistance. Can any of the technical people here calculate what that would be for the Prius, say on a five mile stretch of flat road at 50 mph?