Most efficient braking?

I would say that it is better to brake lightly over a longer period of time. If you live in a warmer climate the hard braking results in higher regen braking current and increase in HV battery temperatures.

The friction brakes engage below 7 mph as you say and that would be when the charge indicator bar is at zero regen.

 

Watch the white bar on the left of the power display. When it maxes out you are no longer regenerating. In my experience this means very gentle braking over a longer distance. The higher the speed the more gentle you have to be on the brake pedal to stay in the regeneration "zone".

Just to be very clear, coasting is the most efficient. Braking, at best, is about 50% efficient if you can stay in regeneration. If not it's total loss braking.

So very conservative driving. Which of course makes other drivers mad. They want to rush up to the red light and wait.

And that's probably what causes Prius hate. Morons!

 

From what I observed, people do that, so they can text while stopped. Some people are so engrossed in it they miss green light change and wait it out entirely. I've seen it myself from a next line!

 

This is a more interesting and complicated question than it seems. In a vacuum (literally!), braking slowly would seem to be the best bet since batteries like a charge at lower Amps and longer times somewhat better. But in the atmosphere, for every second you are travelling at a higher speed more of the car's kinetic energy is being used to heat the atmosphere and less to charge the battery. That would argue that you should brake somewhat more aggressively to get the vehicle speed down to 20 or so mph where there is little air resistance, and put as much of the KE into the battery as you can. Of course, braking too aggressively in that regime is also problematic since it might engage the friction brakes.

My intuition is that a tautochrone-like braking curve would be pretty efficient and smooth. But try to stop braking at 7mph and let the car coast until the light changes or you finally have to stop.

 

I'm a fan of 'pre-emptive' braking if traffic permits. When I see a light that I am likely to have to stop, I brake a little harder to get my speed down to 25 mph and then "N" coast to the end of the line or the light.

Done correctly, my speed approaching the light or line of cars will be 20-25 mph and the light will change before I have to come to a complete stop. I simply follow the cars or accelerate without having lost that last bit of momentum (i.e., kinetic energy.)

Bob Wilson

 

I've heard that, electrically, the most efficient thing to do is to brake moderately strongly, without exceeding the CHG bar; there are some fixed losses in the inverter, and so to minimize the percentage loss, you want to minimize the length of time that you're moving energy through the inverter. (This was from the GII, I believe, but the same should apply to GIII.) Of course, if you exceed the CHG bar, then it's using the friction brakes, and you've lost all your efficiency gains from braking "quickly". I use quotes because even maxing out the CHG bar (especially at high speeds) is still very gentle relative to how many people drive, as others have noted.

 

This is a great question, from a theoretical perspective, but the answer likely has limited practical value. I doubt that the difference between braking that nearly fills the regen display stores, over a short distance, a significantly different level of battery charge than less aggressive braking over a longer distance. Furthermore, undue attention to a dashboard display during braking, in an attempt to store a couple of extra milliamperes, can detract from the reason that you are braking, in the first place. Stating the obvious; the best way to brake is CAREFULLY.