Does anyone know if there is a difference in recharge power between coasting and braking? I'm wondering when I come up to a light, should I keep steady pressure on the brake and slow to a stop or should I coast up and then brake at the end with more pressure? Which would be more advantageous mpg-wise?
moderate braking will regenerate much more than coasting--which does very little. But it's all a trade-off depending upon driving conditions.
I don't brake to recharge the batteries; I brake to stop the car adequately, and allow the system to regenerate whatever it can according to the way I brake. If you think too much about all the details of driving the Prius to maximize fuel economy, it stops being fun.
<div class='quotetop'>QUOTE(jamarimutt\";p=\"110088)</div> i never thought a lack of options was more fun than making my own choices
<div class='quotetop'>QUOTE(jamarimutt\";p=\"110088)</div> To each his own. I find it more fun to continue to explore the limits of maximizing the fuel economy. That said, I agree that goal #1 with the brakes is to stop the car. To that end I avoid using the brakes as much as possible. But once it is clear that the brakes will need to be used I try to maximize the regeneration, minimize the use of friction brakes, and maximize the fuel economy via anticipatory driving.
The Ideal would, of course, be to only coast and never brake. If the choice is between slight braking all the way to the light, versus coasting then 'hard' braking, then the slight braking wins. Remember, all braking below about 8 MPH is mechanical. Regeneration cuts out at that point. Above 8 MPH, slight braking regenerates, but 'hard' braking can also engage the mechanical brakes, which is wasteful. Also, remember that below 20 MPH you can use the "B" mode to get maximum regenerative braking without touching the pedal. That's one of the tricks the Japanese hyper-milers use in city traffic. Since it's very hard to tell exactly how hard you can push the pedal without crossing over to mechanical braking, if you use B to brake initially coming to a light you are guaranteed maximum regeneration. However, above 20 MPH B mode will spin the ICE for resistance, which is just as wasteful as burning brake pads
Thats always been my question. There is some steep hills that I have to go through alot everyday. If I just barely touch the brakes, it helps slow down the car alot, but I wonder If I am barely using the pads also? How much is to much, before the pads kick in at say 50-60 mph?
if you start to brake slowly and gradually, it will be nearly all regen. the key is that if on a very steep hill to start braking early. now you might not want to brake if you will be going back up a hill soon. on rolling hills, not braking at all will be the best way to go if your speed doesnt get too fast. regen is a great way to recapture some of the energy you expend, but its still woefully inefficient. so not braking is better. but if its a long downhill, then braking will be necessary. i would do as little as possible even if it meant going 10-15 mph over the speed limit. of course there will be exceptions and you need to decide what your maximum safe speed will be. i wouldnt ever go that fast anywhere but the freeway. all this discussion is moot if there is traffic signals at the bottom or something along those lines.
So even just slightly pushing on the brake pedal, you could still be dragging your brakes? I try and just push just enough to feel a resistance and thats all. Maybe just slightly more at times. I quess the only way to test it, is try it and at the bottom of the hill, pull over and check the temperature of the front rotors and see how warm or hot they are.
<div class='quotetop'>QUOTE(SDiego\";p=\"110263)</div> if your really curious you could do the braking you normally do and when you get to 10 miles per hour if safe use the emergency brake to bring the car to a full stop then check the front rotors and see how warm they are. Disk brake systems use more front brake before the rears start so if you think your on the front rotors this would tell you. Just remember that front brakes can get very hot so don't put your fingers on the actual rotor or you just might need the good Dr. Fusco.
Turn off the radio and lower the fan speed. Press the brake pedal lightly and you'll hear a whine from the motors. Press harder and that sound will disappear. I use that to gauge how hard to press. Of course, you can only hear it with the radio off cause it's quite soft and even someone talking will drown out the sound.
Coastaletech seems to be working on a mod that visually shows the relative amount of friction braking being applied. Cool idea. http://www.coastaletech.com/new_page_1.htm
it would be nice if someone came up with a scanner tool like the one Frank has for his classic. it shows how much power is been regen. you could use that for to find the most efficient braking techniques since that is what this post is really about.
I got off my lazy duff and went to the costal site and the friction breaking / ICE on visual display MOD is not available yet. Gotta Question regarding breaking and regeneration. First of all I got my battery to go GREEN twice on my way into work by paying more attention to my breaking pressure, even heard the motors whirring at one ponit! I was just applying slight pressure and holding the break pedal there. heres the Question - Does regeneration stay engaged if one activates it with the break pedal then lets off the break pedal until you either depress the gas pedal or engage friction brakes? Lovin' my Prius (almost 700 miles on her now ) thanks.. AL
Don't know if this info is accurate, but... When we took delivery of our Prius a couple of weeks ago, the hybrid sales expert at the dealership told us to coast rather than brake if possible. He said that coasting gives you about 2x the regeneration vs. braking.
<div class='quotetop'>QUOTE(gordonr\";p=\"110699)</div> That is most definately NOT accurate. Multiple people have measured the regeneration both with the THHT and personal electronic measuring equipment and shown that moderate braking is most efficient at regenerating.
<div class='quotetop'>QUOTE(alsgameroom\";p=\"110682)</div> Al, I'm not sure I understand your question. Are you asking if the same level of regenerative braking is maintained after you take your foot off the brake pedal? Of course not. If you are not applying any brake or accelerator pressure you'll get the nominal regenerative braking that occurs when you cost, so some regeneration continues, but not at the level you were at with your foot depressing the brake.
<div class='quotetop'>QUOTE(SDiego\";p=\"110263)</div> No, slight pressure...even moderate pressure on the brakes, if applied gradually, will not engage the friction brakes (on the 2G Prius) at all. There are sensors that detect the speed and amount of pressure applied, so sudden braking, even if not braking that hard, will engage the friction brakes...and you can feel it.
