Regenerative Brakes? Really?

On the Consumption Screen of the MFD, just under the screen title, are the words "Regenerated=50WattHour" (or equivalent). As soon as I turn on the HS, before moving the car, it says that, and it always says that, despite plenty of regenerative braking during a drive. What does that statement mean?

 

It explains the meaning of each such leaf that appears in the five minute mileage segment bars which appear in the consumption display as you drive.

 

Hmmm, I don't recall ever seeing such a "leaf", but I calculated (with some referring to ancient Physics texts) that a 2890 lb car moving at 35 mph has a kinetic energy of 44.6 Watthours. I.e., a single complete stop from 35 using only regen braking (not feasible) still wouldn't restore 50 Watthours to the battery.

But does the MFD "consumption" display computer ACCUMULATE regen'd watthours? Seems as though multiple stops from moderate speeds would eventually exceed 50 watthours accumulated.

Have any of you folks seen the small green leafs?

 

I always thought they were little green cars. Oh well. I get them alot in my morning downhill commutes.

 

Ha! I saw two green leafs myself,today, after a short (under 2 miles, about 6 stops) run to my bank, where I parked in a shaded area and took the time to examine the Consumption screen of the MFD before shutting off the HS. Two of the lil' buggers! Speed was 35 mph max, so I guess the HS computer does accumulate the regenerated watt hours and outputs a leaf for each 50 Watt hours regenerated.
I too thought they were miniature cars at first, but on closer exam, perhaps a dial of a watt-hour meter? "leaf" isn't too bad a description.
WHAT A CAR!

 

It's a leaf cut into the shape of a car. It's in the brochure for the Prius.

[Broken External Image]:http://commons.ucalgary.ca/~king/toyota_lev_leaf.jpg

 

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Very good!

 

Going back to the Locomotive idea...
Shouldn't all trains that use electic lines have regen capability?
Like mass transit trains and the ones that go between countries in Europe?
They could just pump the recaptured electricity back into the lines. Somewhere along the line another train could be drawing that power and the amount of power to keep the lines energized could be reduced significantly. Do some do this already?

 

Trains have friction brakes on every car; the locomotive's braking is a small part of the braking effort. Braking the locomotive alone would probably cause jack-knifing. To use a relatively newly redefined word, sounds "problematic"!

 

Conservation for conservation sake would just be crazy talk. That's why our escalators and people movers run non-stop as opposed to just when someone's on them like most of the world does. How ever would we know the device is working if it doesn't run nonstop?

A Train at full speed and load has so little energy to recover anyway I'm sure it wouldn't be worth the cost to implement a system. :wink: How would the train stay warm if we didn't use the brakes regularily?

All kidding aside, if all electric systems like light rail/mass transit systems don't use regen it sounds like a big waste... the power recovered might not even make it back to the line... I would think the ancillary systems use a ton of juice.. especially the ventilation and A/C.. probalby runs year round on mass transit. I would think a system designed to be all electric from the start would have greater efficiency.. The Prius prob could be more efficient if they weren't trying to make using it just like another car and fit the models alrady created (glad it works like it does.. would scare my mother to death if it didn't)

 

This Forbes article ( http://www.forbes.com/business/free_forbes...5/0411/076.html ) discusses the recent and continuing improvements in power-massaging equipment, such as that which turns the Prius' messy, regenerated AC power into clean DC power to run the motor. It doesn't mention trains at all, but reading between the lines, someday it may be cost-effective to put regenerative brakes in boxcars. Flywheel technology (not discussed here) might also be feasible to store some of the kinetic energy.

The major stumbling block may be the fact that, from an energy standpoint, freight trains are already extraordinarily efficient. Odds are that fuel costs aren't that large a percentage of a train's total operating cost. (Or - how much would you be willing to pay to turn your 250 mpg car into a 400 mpg car? Even at $10 a gallon, if you drive 1000 miles a month, those additional 150 mpg only save you $180 a year.)