Pulse & Glide *-*101

<div class='quotetop'>QUOTE(Rufaro @ Jun 7 2006, 11:29 PM) [snapback]267712[/snapback]</div>

Mo men tum

 

<div class='quotetop'>QUOTE(Rufaro @ Jun 7 2006, 09:29 PM) [snapback]267712[/snapback]</div>

Humm.... I think the idea is that there is no point in using Kinetic energy to make electric energy to burn as kinetic as its put to the wheels again.

The only reason you want energy going to the batteries at all is if your speed is out of control and you need to brake while going downhill or while the ICE is on to go up a hill.

Coasting is the most efficient way to go as far as you can go on a given amount of kinetic energy.
If you let off the brake enough for it to start regening the batteries, you will be slowing yourself down to charge and eating into your kinetic energy or "momentum".

the "pulse" part of the equation is when the ICE has to come on to get back up to speed... if you have used battery and its depleted, the ICE will really work hard to charge it while gaining your speed..

Unless I'm interpreting all this all wrong, I believe the whole transferring energy to and from the battery is to be avoided in pulse and glide because its inefficient.
there are energy losses as it goes into the battery as well as when it comes back out.

I don't know if you had a switch where you could totally disengage the hybrid part and simply use the ICE to speed up and pure glide to slow down, would be the trick or not.
But I don't think so.... there is a certain amount of benift derived from the ICE being on and charging the battery a bit so when you glide you get to use some of that...
But when you attempt to utilize the hybrid facilities to its limits is when you take it in the shorts.

Forgetting pulse and glide and talk about normal driving for a minute, the hybrid really pays off because there are tons of times when your kinetic energy must be wasted by braking and coasting to complete stops and then restarting momentum again.... in real life driving, some of that "what would be wasted" kinetic energy gets to be captured for later use thereby improving the efficiency of you overall driving experience.

But with Pulse and glide, you are turning our commuter plane into a glider... a bit of a different application.
You are on a flat surface and there is "no" kinetic energy to waste.... you want it all for the trip!

the moral of the story with pulse in glide "in my opinion" is that you can utilize some of its theory and application to your real life driving experience by avoiding changing speeds back and forth and avoid braking unless absolutely necessary and try to avoid pulling the battery down to near dead with EV mode unless you are puttering along and doing something the ICe really shouldn't have to do because the work is so easy, and keep your speeds low if possible.

Barring all that I just drive normal... I favor 70 - 75 alot and try to keep constant speeds if possible.....
I believe achieving maximum mpg is cool for fun, but should not become a bondage whereas you are afraid to turn on the air when its over 100 degrees for fear of using gas etc.

The wonderful gas mileage is not worth it if you have to arrive a sweaty pig or a popsickle because you wouldn't turn on the heat.
Even when you drive sensibly and keep you and your family totally comfortable, you still beat the pants of the best luxury cars with your worst gas mileage!.....

Some people live in moderate climates and can get away with no air or heat most of the time, but others need it to survive. In the south when buying a car, you open the hood and see if it has air, then you see if it has an engine! :lol:

 

<div class='quotetop'>QUOTE(Rufaro @ Jun 8 2006, 02:27 AM) [snapback]267757[/snapback]</div>

How about this:

Since you mentioned green arrows, it means regeneration is taking place. Regeneration causes drag and makes you slow down (that's why they call it regenerative "braking"). Since this is all about MPG...."coasting" with regeneration....lets say...from 40MPH...you slow down to 30MPH in 200 feet (just an example..I don't know the real slow down rate...depends on the road too and some other things). Ok...40 - 30mph in 200ft w/ the green arrows (meaning you get drag). Now, with no arrows...actual coasting....you get no drag from the regenerative breaking system...so you go from 40MPH to 30 MPH in 500ft....You get to travel further before having to use the ICE (and gas) to get back up to 40MPH. So...you end up with higher MPG. The further you travel w/o using gas....the better, yes?

As a side note, if you are coming up to a red light, it only makes sense to let the regen braking do it's thing. It slows the car down (you need that anyway), it saves your brakes (nice thing to save on), and it recharges the battery. You are going to stop anyway...might as well make the most of it.

 

<div class='quotetop'>QUOTE(TonyPSchaefer @ Jun 8 2006, 05:57 AM) [snapback]267801[/snapback]</div>

Yea, and there has been discussion as to why Toyota didn't just make it with no drag and no regen when letting off the gas "seems for efficient for the veteran prius driver right?".

But the decided to "simulate" the transmission drag of a normal car and make power in the process.
Most people "want" to slow down by letting off the gas and don't expect to have to apply the brakes.

Personally, I think anyone would get used to it quickly.
But bouncing from car to car as most families have several cars "not all prius's" it could gender a lawsuit if they didn't do it the way they are doing it.

I wish we could tell the computer to quit using regen for coasting and give us a choice... but not so yet.

Pulse and glide is basically trying to disable the regen function by feathering the gas pedal just a bit... you also get alittle benifit from the battery too when you do that because it was charged prior when the ice got you back up to speed.
As I said earlier, if you try and maximize the hybrid features by charging the battery aggressively and draining it aggressively, you will only be wasting power.
Ideal regen is only when you want to capture power that would have otherwise been wasted.

 

Stop? How about, as the locals say, a California Roll. :blink:

<div class='quotetop'>QUOTE(Jim1eye @ Jun 8 2006, 08:12 AM) [snapback]267970[/snapback]</div>

 

<div class='quotetop'>QUOTE(windstrings @ Jun 8 2006, 11:02 AM) [snapback]268065[/snapback]</div>

Mostly car makers think we're idiots. And mostly they are right. Just look at some of the lawsuits to convince yourself. Just like EVERY car has a different amount of compression drag, driving a car with NONE takes about one microsecond to adapt to. I have had several regular gas cars along with several EVs that allow for no compression drag. It is like driving and riding a bike. You simply pilot the vehicle the way it is intended and think nothing else about it. The Prius should definitely have a "no drag" choice. On the Rav it is simply a button on the shifter.

 

<div class='quotetop'>QUOTE(darelldd @ Jun 8 2006, 12:58 PM) [snapback]268177[/snapback]</div>

Well when they first came out with the prius.. we were extremely skiddish about a new thing that didn't have Ford, GM, or Chevy stamped on it.

Even now people are finally realizing "no, you don't HAVE to plug it in" and they are finally realizing there is no learning curve to driving a prius.

maybe after the public feels a little more comfortable, Toyota will allow for free glide and maybe even "add" the plugin features as decent batteries with long distance ablilities become available.

 

<div class='quotetop'>QUOTE(windstrings @ Jun 8 2006, 11:02 AM) [snapback]268065[/snapback]</div>

Actually you do get used to it quickly the old 3 cilinder 2cycle SAAB 86 free wheeled. There was a second clutch on the wheels that engaged when you applied power to the wheels. When you took your foot off the gas the engine was disconected. After the first few times going around a corner with the car you learned to add a bit of brake to simulate engine breaking. You could glide a long way with the engine ideling down hill on the car!

 

Hi All,

Here is another thing to think about the "glide" . The energy recovered into the battery during regeneration (green arrows) was partially used up heating up the gear box and generator, and the switching transistors in the inverter and the wires between the inverter and the battery. Then when you use the battery for stealth mode, those energy wasting losses happen again, only in reverse. So, the regenerate/stealth energy cycle is not 100 percent efficient.

Avoiding regenerating (no arrows) results in only aerodynamic and rolling friction losses at the glide speed. Typically, these losses are about the same in in the stealth operation as in glide. Glide speed and stealth speed are typically similar. So, the mechanical and electrical losses of regenerating and then bringing the energy back out of the battery to the wheels is additional to the aerodynamic and rolling friction losses.

By staying in glide (no arrows) one avoides those extra losses.

Of course this requires a good following distance, and sharp distance/speed vision. Its difficult to gauge closing speeds at 50 yards. And when one reaches a distance where closing rate is apparent, it may be too late to drop into regenerate, and brakes are the only option. Or the opposite extreme, traffic pulls away from you and a good power level is needed to stay on pace.

On a sidelight, there has been some discussion about the regenerate/stealth energy cycle. Some people say its only 40% efficient, while others say 80%.

 

I probrably overexaggerated the GM, Ford bit... but what I mean is people in America are ok with technology if they don't know about it, but when its in their face, they get intimidated easy.. especially women....
They really need to know its trouble free and there is nothing they have to do.

As far as the arrows thing.. its really really hard to not have any arrows unless the battery is fully charged first of all and your speed has to be under 40'ish "unless your battery is even more charged from a recent downhill decent".

So all in all most of what we are talking is theory and hard to capture in real life.

As far as our driving habits:
Its always a game of trading between the lesser of two evils.. there is never a perfect scenario.

 

can't one use N if their foot is lazy?

 

^^ i dont think u can just get into N with out stoppin or pressin the brake

 

I have a question.....

When I get into a mode where there are no arrows, some kind of energy is still propelling the car forward. This is evidenced by the fact that when I take my foot off the gas pedal, the car slows down. Yet, no energy use is present on the screen. What's all this about?

 

<div class='quotetop'>QUOTE(SSimon @ Jun 12 2006, 09:40 AM) [snapback]269964[/snapback]</div>

It only appears that way... in reality, you are coasting a true coast with no arrows.

Normal cars drag with thier inefficeint transmissions, but when you let off the gas with the prius, you slow due to the the generator using kinetic energy from the wheels to make power... a 10K generator!

Anytime the generator makes power it slows the car to the degree of how much power its making "the more you press the brake, the more it generates".

Its an illusion.... you "feel" like there is an energy propelling the car forward, but your really coasting with almost no drag.

Now also keep in mind that the battery can assist a bit to propel you without it showing the the screen... the screen does not exactly or always show whats really happening.

If you get a "Can-View" and install it, you can see the true story better.