Weight penalty of the Hybrid Synergy Drive

<div class='quotetop'>QUOTE(JustLurkin @ Sep 30 2007, 01:07 AM) [snapback]519338[/snapback]</div>

The weight comes from the battery, power electronics and the two motors are solid iron with copper windings. These parts are necessary to make the car efficient. As for claims about light weight leading to higher mileage, that is only true for cars with ordinary brakes. Good hybrids use regenerative braking and that mitigates the extra weight.

BTW, the extra weight is low. This means our hybrids takes turns like no body's business. In fact, I find switching back to my wife's Echo is almost dangerous because it wants to tip over. For fun, take your favorite skeptic to lunch and take a fast curve, twice. Ask them what speed they take that curve at. <grins>

Bob Wilson

 

Hi Just...

Yes. This is a common red-herring used by Hybrid bashers. Batteries and Motors are heavy they say. But the performance gains speak for themselves. I have not done this, but do a comparison of the GS450H and the GS430. Or compare a VW Passat TDI to a standard Passat. The large cast iron Diesel block weights more too, in comparison to the aluminum alloy gasoline engine block. Plus the 30 poud turbo-charger.

In the Camry, the common trick(or ignorance) is that they compare the 4 cyl. Camry with the Hybrid Camry. When the Hybrid Camry is a bit of a power hybrid. A more accurate comparison is with the V6 Camry. The Hybrid Camry is a only a second or so slower than the V6, but a few seconds quicker than the non-hybrid. A valid comparison of a 2.4 Liter Camry would be to a Hybrid Camry with something like a 2.0 liter engine. Which would save some weight.

You see, there are manufacturing/marketing economies to consider as well. Toyota makes millions of those 2.4 liter blocks. This has been the base engine in the 4-Runner ad-infinitum, for example. Its Toyota dogma to reuse any technology where possible on new projects. Those blocks are used in more than just the Camry. So, the manufacturing decisions is do we go with a custom offset crank 2.0 liter engine/hybrid which would match the 2.4 liter accelleration, that had engine costs $1000 more due to no economy of scale. Or do we just add on the Hybrid to the 2.4 liter, and deliver a car with performance in practical driving sitiuations similar to the V6, at a few thousand less than the V6, and a good improvement in fuel economy over the 2.4 liter 4 (versus the 100 % FE improvement with the 2.0 Liter Hybrid) ? In either case the Hybrid is more expensive up front, and many people might think why should I pay more for less horsepower? Even though the accelleration would be the same. The marketing input is Americans buy horsepower, not accelleration or fuel economy. So, Toyota decided to make a car with a heavier drive-train, and more accelleration, and higher initial value (because they can make the engine cheaply) This way they get the sale, they think.

In the end, I do not think the Hybrid Camry is as succesful. Because the people buying the V6, will not opt for the Hybrid (due to percieved performance penalty). And the people buying the 4 wont either (due the desire to get out of the dealarship with the lowest up front cost).

You see, Toyota did not follow its own Prius Religion on the Camry Hybrid. The Camry MG2 is not even as big as in the Prius. This probably happened because the Camry group is a different set of people. And in the end the Camry Hybrid sales suffered. And most of the people who would consider a Camry hybrid, just bought Prius. They did not win very many, if any traditonal Camry purchasers over to the Camry Hybrid. 2.4 Liter Camry buyers might buy Hybrid Camry if the fuel economy was a knockout, but its not. And the V6 Camry people will argue all day long that 1 second in 0-60 is a life-and-death difference, as bizarre as that is. Consequentyly, Toyota only pulled a few potential Prius buyers into the Camry hybrid, and possible a few Ford Fusion buyers. At least, that is the my point of view without any hard marketing research to back it up. Jus the apparent slow sales of Camry Hybrid as evidence.

As to the Prius, the overall performance speaks for itself. And, as long as there is no gravel in a curve, so does the torque as Bob Wilson points out. And that torque is the result of that big heavy 60 hp motor up in front of the driver. Make sure its a left turn you demonstrate on .

The Prius is a car that is bigger than its engine would imply. And its because they designed the drive train first, than increased the size of the car to match the performance the drive train delivered. They ended up with a car that competes with the Camry, although that was not their original intent. They could scale the Camry. The Camry size is fixed. And they did not have enough economies of scale in the smaller engines appropriate for the Camry hybrid, for it to pay off. The Camry 2.4 Liter Hybrid drive train matches the Avalon for 100 % fuel economy improvement.

Other consequences of this? Yes, the motor being small makes the 2.4 Liter Camry Hybrid drive train a poor match for the Sienna Minivan. And this might be why we have not seen the Sienna Hybrid yet. May just not be enough economies of scale to deliver yet.

 

i think the curb weight for the 01 was like 2700 lbs and 05 was 2900, which i consider fairly light for cars this size, compare it to a nissan altima with 3001 lbs or a camry with 3495, Prius was made i believe with weight reduction in mind considering the aluminum hood and hatch.

 

Silly bashers. Who gives a fig how much it weighs? Toyota engineers are not smacking themselves in the head thinking, "D'ohh!! We'd be getting so much more than 45 MPG if only we hadn't built in that 300 pounds of useless dead weight!"

 

Hi All,

BTW, one of the fuel economy articles said that 300 pounds was only a 1 mpg pentalty, anyway.

 

<div class='quotetop'>QUOTE(efusco @ Sep 30 2007, 10:03 AM) [snapback]519461[/snapback]</div>

Yeah, extra weight is bad for efficiency. The space shuttle engineers know this and spent millions just to reduce 1Kg of weight.

I'd love to see these new carbon polymers used in production cars and reduce average weights by 25%-50%. Better performance, economy, AND less damage donw when invloved in an "accident". Force = ma.

 

<div class='quotetop'>QUOTE(donee @ Sep 30 2007, 08:21 AM) [snapback]519379[/snapback]</div>

It has been a while since I did the analysis but I remember looking at the Prius and Camry hybrid sales and I thought there was evidence of a little Prius fratricide from the Camry sales. At the time, some of the skeptics had seen a dip in the montly Prius sales and were trying to claim the hybrid boom was over. Then shortly afterwards, Toyota opened the production lines and another skeptic argument crashed into an unforgiving reality.

Just for grins, perhaps you might take the monthly sales figures for both and see what they look like together.

Bob Wilson

 

<div class='quotetop'>QUOTE(F8L @ Sep 30 2007, 01:07 PM) [snapback]519464[/snapback]</div>

Yes, but they are pushing them into space, which is a whole lot different than over the road. In a non-flying automobile, extra weight increases inertia which makes it more costly to accelerate, and increases rolling resistance since there is more weight on the bearings and tires. If the regenerative braking process were 100% efficient, then the extra inertia would not influence efficiency. The real performance of the regenerative process is less than 100%, but still a whole lot better than not having it. The extra rolling resistance is unavoidable, but minimized with good bearings and tires.

Tom

 

<div class='quotetop'>QUOTE(qbee42 @ Sep 30 2007, 03:09 PM) [snapback]519573[/snapback]</div>

Tom, what you say makes sense but I think fundamentally weight is still an issue. The most efficient design would have us driving vehicles that expended 99% of their energy moving us instead of the vehicle. As it is I believe we are quite the opposite in that 90%+ of the energy used by a vehicle is used to move the vehicle (simplified and not taking into account losses though heat and mechanics) instead of us. So while adding efficiency through regenerative braking techonology is great, reducing weight should still be a high priority no? This why is bicycles are such a highly efficient form of transportation when designed correctly.

*edit*

I found part of an article that better descibed what I am talking about.

Or you can watch a 7min video HERE.

 

<div class='quotetop'>QUOTE(Tideland Prius @ Sep 30 2007, 12:37 PM) [snapback]519480[/snapback]</div>

Another way to make the point: The Yaris, much smaller and 800 lbs lighter than a Prius, has the Prius drive system, minus the hybrid system (and of course a conventional trans). And it seems to get about 10 mpg LESS than the bigger, heavier Prius. These Prius bashers are truly a pack of morons. The car gets great mileage because of the presence of the hybrid hardware.

 

<div class='quotetop'>QUOTE(F8L @ Sep 30 2007, 06:19 PM) [snapback]519577[/snapback]</div>

Right. No question that weight makes a big difference, considering that we drive on rubber wheels over yielding surfaces, and even the best regenerative system only recaptures about 40% of the energy. My point was that there is no comparison between a flying device, especially a rocket, and a car when it comes to payback for weight reduction. With a rocket you have to lift all of the weight, including the fuel and engines. You add a pound of weight, and you need more fuel to lift it, plus more fuel to lift the additional fuel, and potentially a heavier engine to provide the additional thrust, plus more fuel to lift the weight of the bigger engine, and more fuel to lift the additional fuel that's needed to lift the bigger engine. It's a vicious cycle which just doesn't exist in the world of autos. You get some weight multiplication, but nothing like that of planes and rockets.

Bicycles are a highly efficient form of transportation because humans are highly efficient, and the transmissions on bicycles are very efficient. Weight would make very little difference except that all braking energy is lost. Doubling the weigh of a good bicycle would only sightly increase the losses due to friction, as the weight of the bicycle is already small when compared to that of the rider.

Tom

 

In my driveway is a 2001 Echo and a 2003 Prius with both having the exact same engine block and 1,500 cc displacement. Plotting the weight versus mileage:

weight - MPG (EPA numbers)
2150 lbs - 30 MPG (Echo)
2765 lbs - 41 MPG (Prius)

My real world experience is:
32 MPG (Echo)
52 MPG (Prius)

The experimental results suggest weight-only arguments don't carry much . . . weight.

Bob Wilson

 

Which is lighter, the man walking along the road or the same man on a bicycle?
I would say the man on the bike will travel further for less expanded energy even though the combined weight os heavier by exactly the weight of a bicycle.

The machine(bicycle) is used to make the man more efficient in much the same way the relatively heavy HSD system is used to make the 1.5 litre engine more efficient.
Learn to live with it.

 

Numbers, Prius has better number, no argument.
Why bother, he can drive his honda you drive the Prius and the world is a happy place.

 

<div class='quotetop'>QUOTE(JustLurkin @ Oct 1 2007, 12:57 AM) [snapback]519725[/snapback]</div>

The IMA system does a good job of mitigating the low power range inefficiencies of the engine.

<div class='quotetop'>QUOTE(JustLurkin @ Oct 1 2007, 12:57 AM) [snapback]519725[/snapback]</div>

Arguing 'better' in this case is pointless. It is like arguing if vanilla is better than chocolate ice cream. You might head over to GreenHybrid.com and look at the mileage numbers under "Comparison" between the Prius and HCH. You'll find both are pretty much giving the same numbers. There are some subtle differences in the distribution but that takes skill to exploit.

Why don't you and your friend take alternating 'lunch' breaks together. This will give you insights about the HCH and your friend, insights about the Prius.

Bob Wilson