The problem with series hybrids

[dcb]

Originally Posted by winkosmosis

You're missing the point. Most driving in America is commuting, most of which can be done on wall power ALONE.

I think I was the one who MADE that point,

but this thread has gone completely haywaire with misinformation, it is unbelievable the number of unsubstantiated claims in support of the unsubstantiated claim of series greatness

[user removed]

Originally Posted by RobertSmalls

It bothers me every time I hear that line in the railroad ads. No, it can't. I bet a train uses many gallons of fuel just to get up to speed. If you have to move one ton of freight, use a truck. The train will be lucky if it makes it a mile on one gallon.

The railroad ads also neglect to mention the 120mi/(ton-gallon) figure for a fully loaded tractor trailer, and that if you use rail, the load will travel more miles overall, and you'll need a truck to finish the job.

Railroads save fuel, and we should use them more. But their ads paint an incomplete picture.

And a train is actually pretty aerodynamic. It's like a paceline of 100 tractor trailers drafting each other very close. Actually, it's more like a train, with a negligible frontal area, an enormous wetted area, and unfortunate gaps between each rail car.


Anyway, I can tell you my hybrid gets its best fuel economy when the electric system is inactive. Sure, while accelerating, I could use the electric motor to shift the engine to a more efficient operating regime, but I'd have to pay the battery back at an efficiency less than 100%. When, as dcb points out in the first post, 90% of peak BSFC is easily achievable, it really doesn't pay to use the electric.

Given a series hybrid with a certain size engine and electric motor in a certain chassis, you could improve its highway efficiency by making it a parallel hybrid, without exception. Instead of the Volt running its ICE to run a generator to run a motor to drive the wheels, just use the ICE to drive the wheels once battery charge runs out.

A parallel hybrid with a large electric motor could be designed to cruise on the highway near peak BSFC, using the ICE for cruising and the electric for accelerating.

I expect my next car to be a plug-in parallel hybrid with a tiny gas engine and enough electric range to handle my commute.

I read somewhere that the peak BSFC on the lean burn insight motor was close to 49%.

regards
Mech

[user removed]

Originally Posted by roflwaffle

There won't be a 100% improvement for a ~$3000-$4000 premium over a BE hybrid AFAIK. The BE hybrids have already proven to be successful. UPS ordered 200 of 'em, so the proof is in the pudding IMO. I've been hearing about hydraulic hybrids since 2006, and UPS is supposedly testing them too, but they haven't caught on like the BEs have AFAIK. Time will tell I suppose, but if UPS ordered 200 BE hybrids after testing, but no hydraulic hybrids after testing, I have a feeling the BE hybrid is a better deal. Barring of course UPS not being done w/ the hydraulic hybrids or something else preventing them from getting good data to compare both.

A horse is proven to be effective, same logic was used against the first cars.
I guess the grass to hoof comparison has been long forgotten, along with the statement that if man was meant to fly he would have wings.

In the UPS comparison you draw a conclusion without data, just assumptions based on the number of vehicles purchased.

The HH versions supposedly saved 800 gallons of fuel per year on average, while never needing a battery replacement, which would destroy the comparison, and is an inevitable cost.

[NeilBlanchard]

Hello Dave,

I have yet to see any substantiated evidence that serial hybrids are inherently less efficient.

I have offered three substantiated cases where serial hybrids are more efficient:

Diesel/electric trains -- proven because they are more efficient than anything else. They are almost 3.5X more efficient than trucks.

Mini Cooper serial hybrid prototype gets ~2X the FE of a standard Mini Cooper.

FVT alé gets 92mpg (maximum) while the FVT eVaro serial hybrid version of the same vehicle gets 165-275MPGe.

[dcb]

diesel trains have steel on steel (about 15 times less rr than car wheels) and ARE aerodynamic, you can add many cars (tonnage) with little relative .penalty. Facts are facts.

Mini cooper, as I said, doesn't add up, there are no details or explanations of the test conditions, or how it would do on a long boring flat hiway trip. I also don't believe everything I read from someone with something to sell either without any validation and especially if it doesn't add up. But I absolutely certain that it CAN be beat on that range extended boring hiway trip by a choice engine driving a wheel, no if's ands or buts about it. But at an alleged 200 mile range, a lot of folks don't hardly needs a gas engine, which is the stupidest thing about it. Anyway, we don't know what they mean by 80mpg, how much is hiway, how much is wall power, how much is B.S., etc.

FVT is MPGe, which is not MPG, which is part of the misinformation and the problem with trying to mix power sources. see also: Doug Palmear.

[NeilBlanchard]

Hi Dave,

Serial hybrids have batteries (and/or supercapacitors), and this is the basis for their strong advantage over ICE only vehicles. You can't compare serial hybrids to ICE only and ignore the electric mode -- this is why they are used, and it is why they are so much more efficient.

The corollary argument would be to insist that the ICE-only car has to use just one gear for the whole test. Hey, it wouldn't be fair to let it use it's transmission, because the serial hybrid only has one gear!

I'll take a serial hybrid with a discharged battery and you take an ICE and drive it in one gear and we'll see who gets better FE, okay?

[dcb]

I am really just saying that there are energy conversion losses from the ICE in a series hybrid that a parallel hybrid does not have to endure, and in the "range extender" mode these will be magnified.

If I needed to take my EV on a long boring range extended hiway trip, I would add a single speed optimized engine to drive a wheel as noted in my first post. it is essentially A parallel setup with a single reduction (and chains can do that at 98%) or a more efficient transmission than in your typical ICE that doesn't mesh unused gears just for convenience. I don't think the transmission options have been totally explored, but they can be minimized like anything else in a fairly predictible manner (old Mech, that is hydraulic bit is TMI, not able to sort that out right now, maybe another thread?)

series gets the hype for convenience of implementation, you do not have to think about driveline issues, but there are real conversion losses which rarely get addressed and are presented as their optimal values when they are. if a motor is 80-90 % efficient, and a generator is 80%-90% you have a worst case of a %64 efficient ICE driveline and a best of .81 for series.

I'm in favor of EV's, the question is what form of "range extender" is better (series or parallel) for maximum efficiency if you assume R&D in both areas and a driver willing to drive (he can also keep the engine near bsfc by hand, with electric regen and accel as additional options now, or a computer can do it).

But really "electric advantages" apply to series and parallel, it essentially cancels out of both sides of the equation IMHO.

[Tweety]

Originally Posted by Old Mechanic

Ah "stupid" the name calling that disguises the ignorance of the person making the post.

I did not call it a Hydraulic Hybrid, it was many different organizations that apparently your lack of knowledge, reading, or understanding, of the system was your justification in hiding your ignorance with mud slinging and name calling.

But, for the sake of not letting this thread degrade into real stupidity. Lets look at your position.

A series hybrid is one that uses a single method of propulsion, which is the wheel motor in a HH. Now you could bypass the accumulator and drive the vehicle directly with hydraulic motors and not use any accumulator. The two sources of energy to drive the wheels make it a hybrid. Without the accumulator it is not a hybrid.

Maybe that was the pint your were trying to make, but you should drop the stupid comment because it makes you seem ignorant.

The term hybrid by definition is two sources of energy. You could argue that the engine is the only source of energy so it is not a hybrid, however when you take that position you would also have to eliminate the Insight and Prius in your descriptions of what is a "Hybrid", since both derive all of their energy from the liquid fuel you pour in the tank (in their original configurations).

At least in their stock configuration they have no provision for outside replenishment of anything but liquid fuel.

If you want to take the position that there are no hybrids (by your ignorance driven definition) then it doesn't matter to me, but you should consider the fact that calling someone stupid because of your own pitiful knowledge of the design just makes your position seem driven by stupidity since typically ignorance is curable.

Infinitely variable transmissions allow you to adjust the load on the engine by reducing its RPM to the balance point. If the load from driving the vehicle is insufficient then you store the energy in the accumulator. Once that level of storage is at maximum, kill the engine and drive the vehicle with accumulator pressure alone. That's self contained pulse and glide without speed variations.

Can your electric hybrid do that at 60 MPH? Maybe it they put a $10,000 battery in it, but even then it will not get good mileage because of the total losses through too many energy transformations, even when they are individually efficient, as well as the weight of the battery you must carry along.

That's pulse and glide, and you can do that with a hydraulic accumulator, BECAUSE of the total efficiency of the system. You can not do that with electric hybrids, unless you want to keep your speeds in the range of a fast bicycle.

If you want to brag about mileage and how good a hypermiler you are, just remember to also include the average speed of the trips you take. Any decent driver with 5 minutes of training can get 80 MPG in a 90 Civic if they average 22 MPH.

My average speeds are easily twice that amount, and in a lot of cases closer to 3 times that amount. My average mileage is between 55 and 60, with a lot of 300 mile one day trips that no BEV will do for at least another couple of decades without some major battery breakthrough that we have been waiting for, for 100 years.

If you want a $30,000 car that has a 100 mile range buy a Leaf, in a year or so, and use no oil whatsoever, if you can afford a part time car for $30k.

If you think when those BEVs get into the mainstream it is really going to cost you 2 cents a mile you are dreaming. Oh yes BEVs are not hybrids and it will be soon that you will be paying some form of road tax on your BEV, believe it.

Anyone here driven a BEV 20,000 miles? 50,000 miles? how about 100,000?

I think if you look at it rationally there is definitely a place for BEVs, I support their development.

I also understand their limitations. In a job hungry market a wage earner can not afford to limit their commute. They can also not afford to sell their house at a loss and move closer to a job that might not exist in a couple of years.

I would think from some of the responses that some followers of this thread have not read the linked articles in my first post.

They key component in a successful HH is the in wheel drive. Another key component is the overall simplicity of the system and its ability to capture and reapply huge amounts of energy with a virtually unlimited life expectancy, while being capable of reapplying those same amounts of energy at efficiencies exceeding 80% (again impossible with batteries and electric motors).

How much storage do your really need?

The Volt gives you 40 miles with a 400 pound fuel storage capability. The Leaf gives you 100 miles. Battery storage is still the achilles heel of the electric car, the same way it was the achilles heel 100 years ago.

Give me 300 miles for 200 pounds of battery storage with a 10 year life expectancy (required in California) and I will own only a BEV, especially if curbside charging is available (say in 15 minutes). It would be the only car I need, instead of two cars, one for short distance and the other for trips.

No one knows how long it will be before that is available, but at 59 I may not see it in my lifetime.

The first generation of HH will be a launch assist axle with a small accumulator, in the rear axle of a small FWD car. It will get better city mileage than highway mileage, whicle retaining the conventional power train.

The next step will be to use the same launch assist axle to pulse and glide the vehicle (engine on-engine off)at most speeds up to about 60 MPH, while still retaining the conventional powertrain.

This can be done with a cost to benefit ratio that pays for itself in months, not years.

As the technology matures the dedicated (no conventional powertrain) can be the next eveolution of the system. When you rationally consider the components eliminated the cost is actually less than conventional and the benefits immediate with no break even point to even consider.

Read the links, thats not my data.

regards
Mech

Well, how is that for the pot calling the kettle black? I don't know how you view things, but repeatedly calling me ignorant based on your skewed conclusions isn't very different from my use of the word stupid... (admittedly a bit unfornately worded, yours however is intentional...)

I did not make any claims as to my hypermiling... I'm not hypermiling, as I commute to work by train and bicycle and have no daily driving car... Hence my presence here as I'm about to build a DIY EV for short driving when I need to move stuff larger than what fits my backpack...

I also made no claim on range/performance of any electric hybrid... You just pointed out that I was talking about a non-hybrid car and the reasons why (no accumulator), I'm not claiming to know more or less than you as I have no knowledge of your background... You are however claiming to know more than me... True or not, your explanations needs work as I'm guessing you are thinking more than you are actually typing (makes it hard to follow your train of thought)...

I'm hovewer making the claim that the hydraulic system of transfering power from an engine to the wheels is more efficient than the standard clutch/gearbox/driveshaft... Can we agree on this?

And yes per the defenition you set, OK... Lets call the system with an accumulator a series hybrid... Why, then in terms of technical explanation will an electric motor not be at least as efficient instead of the ICE as it is in a standard mechanical system?

Or if you prefer, we can go back to slinging mud... Or just consider both of us sufficiently mud covered and move the discussion onwards... Your choice...

[Tweety]

Originally Posted by NeilBlanchard

Diesel/electric trains -- proven because they are more efficient than anything else. They are almost 3.5X more efficient than trucks.

Yeah, they are 3.5X more efficient than trucks... As long as you haul the stuff to the train by a truck... And in that same way of comparing stuff it's 100% more efficient to carry all the stuff around by yourself with your own arms... Uses nu fuel whatsoever...

Apples and oranges... Many diesel-electric locomotive also has electric tenders (i think that's the word for it in english) because if you where to try to start a large loaded train from a standstill on the electric power generated onboard by the diesel, the efficiency is in lack of actual numbers, best described as useless...

The diesel electric is meant to be able to go on both electrified and none electrified tracks and yes, it rather efficient as a standalone, but not to anywhere near those figures quoted above... Comparing the diesel electric train to a roadgoing hybrid of any kind is like comparing it to a prius with a 50+ mile extension cord... Not a fair comparasion at all...

[user removed]

Originally Posted by NeilBlanchard

Hi Dave,

Serial hybrids have batteries (and/or supercapacitors), and this is the basis for their strong advantage over ICE only vehicles. You can't compare serial hybrids to ICE only and ignore the electric mode -- this is why they are used, and it is why they are so much more efficient.

The corollary argument would be to insist that the ICE-only car has to use just one gear for the whole test. Hey, it wouldn't be fair to let it use it's transmission, because the serial hybrid only has one gear!

I'll take a serial hybrid with a discharged battery and you take an ICE and drive it in one gear and we'll see who gets better FE, okay?

Serial hybrids have a single propulsion source.

Nothing limits that to electric motors.

As far as transmissionless that is also a misconception.

EVs have far to go in development and using a large primary drive motor will mean greater weight.

Green Car Congress: Antonov to Develop 2-Speed Transmission for EVs

Two speed transmission for electric vehicles.

I actually like the hydraulic energy damper for electric vehicles which has the ability to double (possibly triple) regenerative efficiency.

Also would allow for peak efficiency of primary electric motor operation and lightweight in wheel drives that are non electric.

If you can pulse a glide any vehicle, including BEVs, then you can improve their efficiency beyond their design limits.

That was demonstrated in 1970 with an Opel Kadett that managed 125 MPG while averaging 26 MPH using pulse and glide the year I turned 20.

The combined energy conversion processes involved in electric drives doom them to obsolescence.

The cost of storage dooms them to obsolescence.

The complexity and poor regenerative capacity dooms them to obsolescence.

On the other hand with in wheel drives and an accumulator with a single acceleration event capacity, allows you to do 0-60, back to 0. 0-48, back to 0. 0-35, back to 0. 0-28, back to 0. 0-23, back to 0.

That requires no consumption of any stored energy source, electric or liquid fuel.

In the typical scenario where you are commuting to work in heavily populated areas this is reality.

If you are recovering 33% of the energy the number of cycles becomes pitiful in comparison to the hydraulic option.

A typical 60-0 panic stop requires only 14 revolutions of a vehicles wheels. In those 14 revolutions you will never be able to recover 80% of the energy electrically.

When you realise this is factual, you should understand that there is another option.

It does not preclude battery power to the vehicle or the BEV option, but it does mean your power train will need to be hydraulic with an accumulator.

Why there seems to be a single minded obsession with all electric drives simply astounds me, especially in a forum where people should be dedicated to greater efficiency as well as realistic cost per mile calculations that determine the true feasibility of any practical form of transportation, regardless of the energy source.

But the we all have our agendas, right?

regards
Mech