regenerative braking

[jkbrand]

Having read a couple threads on this subject, I still remain confused on some of the subtleties.

Imagine my having to stop at a light that is, say, 1/8 mile away; I lift my foot from the accelerator and observe I'm gaining charge. Assuming that I also choose to use the brakes, will I have garnered more charge than simply "coasting" over the same time interval, or is there little or no difference? Why?

 

[hybridbear]

Having read a couple threads on this subject, I still remain confused on some of the subtleties.

Imagine my having to stop at a light that is, say, 1/8 mile away; I lift my foot from the accelerator and observe I'm gaining charge. Assuming that I also choose to use the brakes, will I have garnered more charge than simply "coasting" over the same time interval, or is there little or no difference? Why?

Check out this thread from the Fusion Energi Forum for lots of great data: http://www.fordfusionenergiforum.com/topic/2566-efficient-ev-mode-driving-techniques/

 

[michael]

First of all, to be clear....lifting the throttle and lightly applying the brakes are a continuum of regenerative braking. They represent greater and greater amounts of regenerative braking. Putting the car in "L" is equivalent to being in "D" and lightly braking. Heavy braking is different...the friction brakes are engaged.

Having said that, you are slightly better off coasting than trying to regenerate. If you regenerate, energy is lost charging the battery, and more energy is lost taking that same energy back out of the battery. Picture-perfect is if you can modulate the throttle for zero power in or out of the battery, slowing only from friction. Maintaining steady speed is almost as good. But trying to get a lot of "regen" wastes energy. It creates a good regen "score" but is not efficient.

And of course, safety matters. If other cars are around one needs to resist the desire to save every last bit of energy and conform within reason with the flow of traffic.

One other point is that I don't know (maybe someone does??) whether applying the brakes lightly risks slightly dragging the pads? I have that the Honda FIT EV has a valve that avoids applying any brake pressure to the friction brakes until needed. Light braking on the FIT is guaranteed to be purely regenerative. Anyone know if the FFE has this feature?

 

[EVA]

There's theory and there's practical. My leaning is to be practical about it - figure out how to get 100% on the brake coach for every stop. That seems to be a good balance between keeping up with traffic and recovering energy.

Pretty sure the answer on the brake pads, no touch of the pads until the car comes to almost a full stop. Even if they touch, it isn't much - the majority of the stopping energy is going back to the battery.