Regen under 30mph

I don't have a definitive answer for you but based on what I know I would say that most likely it's maximum generating capacity does fall off as you go slower. At just above 7 MPH there may not be much generating capacity left and that's why it shifts to the friction brakes. Maybe someone with instrumentation such as CAN-View will be able to provide a good answer?

 

<div class='quotetop'>QUOTE(tumbleweed @ Jul 22 2006, 11:32 AM) [snapback]290558[/snapback]</div>

And lets hope that the same result for older than 2006 models are the same for the 2006 Prius. Can-View is not yet availalble for the 2006 Prius.

With that said, I will be interested in seeing the Can-View results.

 

the amount of current that gets generated and sent to the battery drops down to probably about 6 amps just before regen drops and the friction brakes get used. At 30 mph/50 kmh about the max you'll see is about 80 amps maybe a bit more but if you press to hard and go thru the stroke simulator on the brake controller you get friction brakes and regen.
On the Classic I get at 30 mph/50 kmh about 45 amps dropping to about 4 amps as the regen drops off. The values for the 2k4 2k5 and 2k6 should all be the same as the system hasn't changed.

 

What Tumbleweed and Frank are saying, David, is that you get some regenerative braking right down to the point the friction brakes take over. You generate more electricity when you have greater kinetic energy (forward motion) that the motor/generator can use. When you are moving fairly slowly, around 7 or 8 MPH, the forward motion doesn't generate much electricity and friction braking provides a smooth stop.

 

My regular mechanic did my 30K check up and suggested that I might want to use my brakes at least once in a while they had rust on the drums and disks! Pad ware, he called it 90% but told me unused was closer to the truth! How about pads every 250K?

 

you can get very high regen numbers even at low speeds on steep hills. i now live on the side of a hill and will hit 80-90 amps even at speeds as low as 20 mph (have to brake firmly to keep speeds within reason which is about 15 mph)

 

<div class='quotetop'>QUOTE(DaveinOlyWA @ Jul 22 2006, 07:54 PM) [snapback]290748[/snapback]</div>

It's all about energy conversion. High speed and flat, car has velocity kinetic energy to convert to electrical energy. Going down a steep hill, potential energy of acceleration of gravity can be converted to electrical energy.

But energy conversion is always less efficient than direct use. It takes energy to accelerate on the flat before you slow down, it takes energy to get up the hill before you come down. A Prius is more efficient than a conventional car because it captures some of the energy a conventional car just turns into heat in the brakes. Entropy rules!

 

a week or so ago I was on the down hill to work and had it in B and a bit of brake and was regening 53 amps and the traffic sped up so put it in D and without modulating the brake all I was getting was 19 amps. Same speed same brake pressure just the difference between B and D. Go figure. Made a mental note as it was supposed to be the other way around.

 

BTW, how do you guys know how many amps you are regenerating? Is there a screen setting that tells you?

 

<div class='quotetop'>QUOTE(Porsche403 @ Jul 23 2006, 12:18 PM) [snapback]290966[/snapback]</div>

One (hyphenated) word: CAN-view

 

<div class='quotetop'>QUOTE(Betelgeuse @ Jul 23 2006, 11:22 AM) [snapback]290969[/snapback]</div>

Bummer, it's not available for 2006.

 

<div class='quotetop'>QUOTE(Bill Merchant @ Jul 22 2006, 11:52 PM) [snapback]290856[/snapback]</div>

Hi Bill,
In theory what you say is true. My guess is the regenerative brake uses magnetic coupling and the magnetic flux versus current curve is generally not linear for magnetics and as such there may be a sweet spot for current generated versus speed going down hill. Until I get a CAN-View for my 2006 Prius I will have to rely on data from others regarding this. And this stil obeys conservation of energy. And increasing entropy.

BTW, all this ignores the SOC of the battery as there may be some other effects regarding the charge controller limits as a function of the battery charge.

 

SOC clearly has its influence on the system. Battery temperature is also an important factor.

 

Hi David


Note on these diagrams that the state of charge is not reflected in a linear fashion, as detailed on this page:


http://privatenrg.com/#terrainfollowing

So, the actual SOC may not have as large an impact on regen as it appears... of course, it also might! The CAN-view can more accurately display the SOC than the MFD, from what I've heard... I can't wait till they come out with a 2006 compatible version!

Dave


<div class='quotetop'>QUOTE(Path2ground @ Jul 23 2006, 07:53 PM) [snapback]291151[/snapback]</div>

 

<div class='quotetop'>QUOTE(Porsche403 @ Jul 24 2006, 07:02 AM) [snapback]291108[/snapback]</div>

You can make your own SuperMID C-1.
http://priusdiy.fc2web.com/C-1.html
(Sorry in Japanese only. The Babel Fish site maybe help you to translate.)

Ken@Japan