The problem with series hybrids

[NeilBlanchard]

Nitrogen? Is there a bladder, and does it have to stretch? How many "cycles" will it do?

[user removed]

Originally Posted by roflwaffle

There's plenty of data. A HH conversion for a pickup costs $13,000 plus labor, so probably around $15,000 and up. A factory 2-mode hybrid system carries a ~$4000 premium over a similarly equipped model out the door. Certainly an OEM w/ a HH option would charge less than $15000 since they can purchase in volume, but I haven't seen anything to indicate that it's cost competitive w/ battery electric hybrids.

Is it fair to compare a factory electric hybrid to a conversion HH?

How much would it cost you to convert a Corolla to an electric hybrid?

Probably a lot more than any HH conversion.

Accumulators are very simple. Think of a bottle of nitrogen you get from the welding shop. Then place a very strong balloon inside the bottle. Precharge the balloon to 1000 PSI. Pump fluid into the bottle and collapse the balloon.

Life expectancy is measured in thousands of hours of continuous operation, and when the balloon fails, you buy a rebuild kit, that is basically a new balloon, for less than $100 bucks.

Been around forever. Very mature technology. Used as backups for landing gear in aircraft. Virtually impervious to temperature variations. Used in excavators. and other heavy equipment.

In the same way your shock absorbers smooth out the ride in your car, and accumulator smooths out the huge variations in energy demand and recovery in a HH vehicle.

Why do we need huge batteries and capacitors to do what the simple accumulator has been doing for decades, even centuries. In England before they even had electrical power transmission they used hydraulic "water engines" driven by pressurized water from giant centrally located steam engines in the late 1800's. Boiler explosions were serious concerns and water engines were impervious to fire.

Look at this objectively. Pulse and glide is proven to be efficient. it's simple and totally effective. When you pulse and glide, your car is the accumulator.

To incorporate P&G into the vehicle, you need to accumulate energy and apply it consistently. The accumulator allows you to do this, when you combine it with an Infinitely Variable Transmission that has no fixed gear ratios.

This allows you to pulse and glide the accumulator and engine, while applying the exact same amount of power to the wheels by constantly increasing the displacement of the in wheel IVT as the accumulator pressure declines.

No vehicle speed changes necessary.

When the accumulator pressure approaches its minimum level, the engine fires up and pressure in the accumulator rises as the IVT displacement reduces to maintain a consistent X value of horsepower to the drive wheels.

It's not all wheel drive because I like AWD (although it's very useful in low traction situations). It's because you must recover energy from every wheel for greatest regeneration efficiency. Any individual wheel can be set to neutral (no stroke-no displacement) any time at any speed, almost instantaneously.

If you can drive your car every day using only the emergency brake (and many here probably can) then you would only need 2 wheel regeneration.

Is it practical to sell a car like that?

Nope.

Burn and coast, P&G, hypermiling, call it whatever you like, but it is basically turning your car into a hybrid, by storing inertia in the mass of your car itself.
With an accumulator and in wheel IVTs you do the same thing tactically, without the speed variations necessary in P&G.

The IVT is the crucial component. The EPA designs were inefficient at higher speeds because the hydraulic motor speeds were too high. In wheel drives reduce motor speed by 75%, where motor efficiency is in the 90+% range.

Revolution sensors in the wheels used in ABS and traction control are another requirement, to provide the speed signal for the control unit to adjust the IVT displacement to maintain speed while energy storage is depleted. The effective gear ratios in the in wheel drives would be constantly changing.

The OP in this thread addressed the issue of combined energy losses in series hybrids. That is the core understanding of this design. Is it to hard to believe that you can actually build a simpler and less expensive system and accomplish what we do with P&G with a lot more driver input than the average driver would tolerate?

Simple
Robust
Long life expectancy
Less expensive than conventional configuration
(when you compare factory mass produced examples of both types-not factory produced versus conversions- which is really not a fair comparison)

Like I said before, if your situation only requires short range operation, then use a battery for your primary power source.

If you need greater range use IC or other methods of propulsion.

In the same vehicle which means you can have both for less than the price of a Nissan Leaf.

regards
Mech

[NeilBlanchard]

Is there such a thing as a hydraulic-only car? If so, how would the accumulator be pressurized? Or, will there always be the need for an ICE or some other fuel powered source?

After the hydraulic fluid is run through the motor(s) and is not under pressure, you have to have a holding tank, right? How do internal frictional (or expansion?) losses affect the flow, especially in the motors?

[user removed]

Neil, check out the links in post #9 and post #25.

This Innas link (in post #9) is very thorough and a direct comparison between an otherwise identical vehicle.

regards
Mech

[dcb]

Originally Posted by Old Mechanic

Neil, check out this links in post #9 and post #25.

Old Mechanic, check out this link http://ecomodder.com/forum/newthread...newthread&f=32

[user removed]

http://ecomodder.com/forum/showthrea...ted-10330.html

regards
Mech

[roflwaffle]

Originally Posted by Old Mechanic

Is it fair to compare a factory electric hybrid to a conversion HH?

It's better than claiming a HH is superior to a HEV when there are no viable examples of it in production, while there are many viable HEVs. On the same note, I'd probably put PHEVs in the same category as HHs in this context. Both will improve mileage, but at ~$15,000 a pop they aren't viable compared to HEVs. Even w/ mass production, it isn't likely that costs will lead to wide adoption of HHs give the EPA's projections regarding long term cost.

Originally Posted by Old Mechanic

Accumulators are very simple. Think of a bottle of nitrogen you get from the welding shop. Then place a very strong balloon inside the bottle. Precharge the balloon to 1000 PSI. Pump fluid into the bottle and collapse the balloon.

Life expectancy is measured in thousands of hours of continuous operation, and when the balloon fails, you buy a rebuild kit, that is basically a new balloon, for less than $100 bucks.

Been around forever. Very mature technology. Used as backups for landing gear in aircraft. Virtually impervious to temperature variations. Used in excavators. and other heavy equipment.

In the same way your shock absorbers smooth out the ride in your car, and accumulator smooths out the huge variations in energy demand and recovery in a HH vehicle.

Why do we need huge batteries and capacitors to do what the simple accumulator has been doing for decades, even centuries.

Because accumulators are heavy, and don't store a whole lot of energy compared to batteries. When batteries were relatively expensive/heavy, it was conceivable that a HH could compete in a cost effective manner. W/ NiMH/Li chemistries, that isn't the case currently. The EPA placed the energy density of composite accumulators, which are a tenth to a fifth of the weight of steel piston type accumulators, at about 50kWs/gallon. 50kWs/gallon is about 14Wh/gallon, so even w/ 22 gallons that's only ~.31kWh, and it still weighs ~240lbs. The battery pack in a Prius for instance stores ~1.3kWh and weighs ~120lbs. My guess is that an order of magnitude difference in energy density is why HEVs have proven popular/successful and HHs haven't. There are certainly applications where weight isn't an issue, the system can be sized to meet specific driving patterns, and a greater number of stops/starts means that there's an advantage to a more robust energy storage device. Stuff like yard hostling and grabage delivery comes to mind. But for the most part energy density is why we see a ton of HEVs but not many HHs.

Originally Posted by Old Mechanic

Look at this objectively. Pulse and glide is proven to be efficient. it's simple and totally effective. When you pulse and glide, your car is the accumulator.

To incorporate P&G into the vehicle, you need to accumulate energy and apply it consistently. The accumulator allows you to do this, when you combine it with an Infinitely Variable Transmission that has no fixed gear ratios.

This allows you to pulse and glide the accumulator and engine, while applying the exact same amount of power to the wheels by constantly increasing the displacement of the in wheel IVT as the accumulator pressure declines.

No vehicle speed changes necessary.

There's also no need for P&G when an engine is geared to always run near peak efficiency. Continually using an accumulator to load level an engine is moot when appropriate gearing can do the same at a similar levels of efficiency, and an electric motor can provide plenty of acceleration until the engine revs high enough to make the rest of the power, all in a system that weighs hundreds of pounds less and costs thousands of dollars less, all things being equal of course.

[user removed]

Regeneration of electric hybrids-pitiful compared to hydraulic

Life expectancy of electric hybrids-pitiful compared to hydraulic

Retained value of electric hybrids compared to conventional
Pitiful
Compare the resale value of a 2003 Corolla to a 2003 Prius, a cost you choose to ignore in your cost comparison.

In 1971 in an attempt to make body shops look like they were making exorbitant profits the insurance company had a body shop estimate the cost of building a $3000 Chevy from scratch using new parts.

$17000 which demonstrates the flawed comparison between any assembly line built vehicle and one built outside of an assembly line.

Conversions versus factory mass production are false comparisons.

The EPA cost calculations included carbon fiber accumulators.

Unnecessary

The EPA calculations also included a plea for a "new sheet of paper" in concepts and designs, which is exactly what my patented design constitutes. They could not possibly calculate the cost of something they did not know existed.

Obvious flawed comparisons.

No increase in vehicle weight.
No increase in overall vehicle cost, in fact a reduction in complexity and cost compared to a non hybrid.
No long term catastrophic battery or electric motor replacement costs that would equal or exceed the value of the vehicle not even considering the additional hybrid electric components.
Peak engine efficiency at all times without exception. You can not get that with gearing alone, even with an IVT.

After a year of research 8 students and a MIT doctor of engineering concluded that the design I developed was a cost effective alternative that could equal or exceed the efficiency of electric hybrids.

If you want energy density in a battery try the flywheel batteries developed by NASA for space exploration. Easily beats any chemical battery you will see in the next hundred years, but no one can afford the price.

$15,000 car with double conventional mileage, no brakes, no power train in the conventional sense, not even including the enormous additional complexity of an electric hybrid.

The fact that electric hybrids are already in production does not mean they are the best solutions, that logic could be used to defeat any significant improvement in vehicular transportation over the last 100 years.

regards
Mech

[dcb]

There is plenty lapses in logic to go around Mech, i.e. "500 hp in your hand" (but ZERO mention of efficiency at that rating, which is the entire point of this forum, and which is historically atrocious for hydraulic systems at higher RPMs), or saying a hydraulic doesn't have a driveline (it damn well does, only it has to pump gobs of fluid under very high pressure through fairly small pipes).

But it still remains that ANY energy transformation from an ICE to the wheels will have losses, and if you are operating at relatively constant speed and load then you can tune a direct drive ICE to higher peak overall vehicle efficiency than either electric or hydraulic drivelines.

Being primarily a flatlander, and fancying myself an efficiency aware driver, and something of a cheapskate, I should see the least fuel usage AND the leasts costs with a simple "hiway use" ICE for parallel setup, period. To me these series hybrid range extenders are inherently less efficient in this range extending role.

And back to the OP, that is the problem, series is crippled by inherent conversion losses that reduce its peak efficiency, so can we talk about what those losses are so we can quantify the problem? Lets say we have a vehicle moving at a certain speed on a flat road:

if you assume an electric motor is 90% efficient, and a generator is 90%, and a controller is 95%, the "transmission" here is %77 efficient, and is noticably more complicated and costly than a chain and sprocket driving a wheel.

The hydraulics I've seen are for big and slow, moving launching pads around and stuff. Trying to move a relatively thick fluid through pipes quickly will incur dramatic pressure drops and efficiency drops, so the dynamic range of hydraulics (while retaining near peak efficiency) is not good at all without very large pipes and hoses and motors. And for fixed speed/load driving like I am describing in the original post, I'll take direct drive for even more peak efficiency and less cost and weight and complexity and maintenance and ???.

[NeilBlanchard]

I think that hydraulics and hydrogen suffer from some of the same problems: they are both merely storage mediums, and they both depend on an actual energy source in order to work. Electricity is an actual energy source, that has numerous sources; some of which are renewable.

Hydraulics may be a great transmission system, and it may be a good way to regain energy, but you still must have an actual power source. If it burns "old carbon" fuel, then it is not a long term solution. Things like steam or biodiesel can get energy from "short-cycled" carbon, and so they would be good long term solutions. Hydraulics obviously work well for very large, heavy construction vehicles and medium sized delivery vehicles. I wonder though, if a small(er) vehicle system would be viable, though.

Hydrogen fuel cell vehicles are really series hybrids; and they replace a larger battery or a small ICE with an extremely expensive fuel cell and a critical high pressure storage system. Since it takes a lot of energy to produce hydrogen, and it takes a lot of energy to compress it, and so you would be a lot better off using a fraction of that power in a bigger battery. Or, use a steam or biodiesel generator, which cost a lot less and have much higher energy density.

An ICE only vehicle only works as a long term solution IF it burns a "short-cycle" carbon fuel; like biodiesel. Otherwise, it is only a less bad solution -- the engines are a maximum of 37% efficient (or so) and they by definition cannot be used at peak efficiency for part of the time. They have to warm up, you have to have a stop/start system to eliminate idling, and because they are mechanically linked to the speed of the vehicle, they must use a transmission. And they cannot have any energy regeneration; only conservation. They require lubrication, which is petroleum based, and they need other regular maintenance.

Electric vehicles have many advantages: electricity is already widely available from numerous sources, electric motors are very efficient, they have no warm up time, they have maximum torque at 0 RPM, they inherently work for regeneration, they do not idle, they last a very long time, they require virtually no maintenance. Since electricity *can* come from renewable sources, any losses are not important in terms of the environment; only to the actual operation.

It is the batteries that are the limitation to EV's. But, some of the problems are easy to overcome -- they can be fully recycled, and if they have *enough* capacity for most trips, then it doesn't matter very much that they don't work for ALL trips, because there are other options; including public transportation, renting/borrowing a efficient car. OR, you can make an EV into a series hybrid, using a biodiesel of some other renewable fueled ICE.

Yes, currently batteries are pretty expensive to buy, but they are very low cost to operate. Energy costs are much smaller than an ICE, and the regular maintenance costs are virtually zero. Battery replacement costs will come down over time, and even if they do not, they are still similar to the lifetime fuel costs of an ICE. Plus, all the money you spend on an EV *stay* in your local economy. The overall carbon cost is much better than any ICE powered vehicle that burns "old carbon" fossil fuels.

And lastly, and EV or an electric series hybrid gives you regenerative braking -- an using a supercapacitor and "smart" GPS based control systems can increase the amount of energy you can regain.

Parallel hybrids are inherently more limited (than an EV or series hybrid) because they *must* use both motors in combination much of the time, and therefore they will weigh more, cost more, and they need a transmission. They gain some advantages, but they also have some of the limitations of both. Again, if the ICE portion of a parallel hybrid (like any other system that use an ICE) can come from a renewable source, but they are still going to suffer from the other disadvantages.