Lithium-ion batteries could ease fuel and evironmental woes

[jpak]

http://www.chron.com/disp/story.mpl/headline/biz/5908508.html

SAN JOSE, CALIF. — The lithium-ion battery, already a fixture in personal electronic devices, soon will become the answer to high oil prices and environmental concerns as it bulks up to power rechargeable electric vehicles, government, university and industry panelists predicted last week.

But although the technology shows great promise, battery makers worldwide still are grappling with high costs, the impact of charging and depletion on battery life, keeping the batteries cool and other issues, according to panelists at the Plug-In 2008 conference in San Jose.

Tien Duong, who works in emerging battery technology with the U.S. Department of Energy, told the group he believes lithium-ion batteries are ready to start displacing the nickel-metal-hydride batteries now used in many hybrid gas-electric vehicles.

Hybrids are powered by electric and internal combustion engines, while plug-ins operate exclusively on electricity.

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[gateley]

1. I know a while back,

Biden got legislation approved to get money for research in lithium ion batteries -- don't know what has come of it.

I think it's a good INTERIM step! I'll gladly promote them as I tool around in my Tesla Roadster. (I'm dreaming.)

[Bruce McAuley]

2. I wish I could afford them for my electric bicycle...

Last I looked they were about the cost of the electric bicycle itself. My Target electric bicycle has lead acid gel batteries, in a 24 volt configuration, but they are damnably heavy and give me about 1 hour endurance, total.
I'm hoping they come out in the next couple years in larger bricks for ease of use, and I'll put them in my bike.
If the battery performance doubles in the next few years so does the endurance and performance of my bicycle. I also have a child trailer I bought at a yard sale so I can bring home the cat food and milk and beer from the grocery store.
On edit, the newer batteries now cost around $500 for my $400 bicycle on eBay and they come from China.
(sigh)
Maybe next year when production ramps up more...

Bruce

[gateley]

3. Batteries have got to get more affordable and become more lightweight.

With the R&D into the technology now, it shouldn't be that much longer. Hang in there!! :hi:

[DCKit]

14. Yeah, but it seems nobody is willing to market them until they're "perfect".

A123 is one of maybe three companies with anything on the market.

Granted, there are manufacturing, cost, liability and warranty issues, but, as with solar electric, the next big thing has been right around the corner for three damn years now. That's one hell of a corner. How long do we have to scream for this before someone realizes it might be a good investment?

'K, I'm just frustrated 'cause I want it available yesterday. The cost of Li-ion batteries for an electric car with a range between 30-100 miles is currently between $10K and $30K, for a bike, over $500, a scooter, $1,500. Add that cost to the premium everyone seems to charge for a "green" vehicle of any kind and you're talking a chunk of cash - Why pay $24-$28K for a Prius when you can get an econobox for half that and use the difference to pay for $5/gallon gas for the lifetime of the vehicle?

And why is it so difficult to engineer an affordable electric car? Toy manufacturers have been doing it since I was a kid in the 1960's. WTF is Detroit's excuse? Everything but the drivetrain and computer are off the shelf components.

[Nederland]

15. It must be difficult

And why is it so difficult to engineer an affordable electric car?

Obviously its not as easy as people think. There is good money to be made producing affordable cars, and if it was easy everybody would do it.

[skids]

4. How many watt hours do you need?

http://www.toolbarn.com/product/dewalt/DC9360/

http://slkelectronics.com/DeWalt/index.htm

http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=2777&p=45245

I guess you'd have to rewind the motor coils for 36V though, or get different motors, or break the packs up and use your own speed controller.

I have often wondered whether an e-bike could not be built that was entirely powered by a dewalt 36v power drill that you just clamp onto a gearing system with a mechanical couple to the trigger. Though you'd be missing regenerative braking that way, but IIRC most e-bikes do not have it anyway...

[Bruce McAuley]

5. That might work...

Most ebikes are 24, 36, or 48 volts, mine being the least expensive at 24 volts, but I actually think my motor might work on 36 volts. I was looking at a 24 volt battery pack with a reserve of 10 amp/hours or 20 amp/hours sold on eBay, with the 20AH version going for around $500 delivered here. Are those DeWalt units lithium ion batteries? What about the Makita or Ryobi batteries? Maybe I should be looking at yard sales for those kind of batteries...
My bike doesn't have regenerative braking.
Thanks for the heads up, I'll be on the lookout for those. :hi:

Bruce

[lfairban]

6. What you got was an entry level e-bike.

I recall hearing that the bike you have will only go about 8 mi. @15 mph with no peddling. I have a similar bike that I get about 20 miles out of with constant pedaling.

You can waite about a year till the batteries are about worn out then replace them with something better, like this for $385. Li-Po batteries are more stable than conventional lithium. It will have more pep because it is 26 V, not 24 V, and has better power density.

OTOH, you might want to upgrade the whole bike and get one with a better, lighter frame, a more efficient hub motor AND lighter batteries.

People have run the Currie motors with 36 V, but it will void your warranty and make it easier to burn up your motor. Read discussions on the e-bike forums first, such as:

http://www.motoredbikes.com/showthread.php?t=6617

One of the changes with the bike you have is that it looks like they are using their own SLA batteries, where the one I have uses standard batteries like this:

http://www.ragebattery.com/power-sonic/SLA-10-12.html

One alternative that you may wish to consider is getting a couple 12V SLAs, wiring them in series, and wiring a plug that will work with the charging port. You only need to use them on your more demanding excursions. OTH, Currie might sell you another SLA pack that goes on the other side, but it will be more expensive that way.

[Bruce McAuley]

10. Thanks for the links...

I need to keep abreast of the battery availability, especially when the stock unit starts getting flat. I have an early mongoose with the single battery placed low behind the seat post, but I could upgrade to some doubles with some work on my back rack I guess.
Good to see others getting into electric bikes too and information flowing about mods.

Bruce

[skids]

8. They are new advanced nanotech Lithium FeSO4 batteries...

...you won't find them at tag sales. The 36V line is the caddilac line of power tools. Sometimes you can find used sets on E-Bay but generally not battery packs. These should last 10 years and take a good amount of abuse. The Dewalt charger IIRC does a full charge on these in one hour (the cells can actually take a 15 minute full charge.) There are tips on the various e-cycle forums on how to set these packs up in series if you want to go 72 volt. Stuff like where to set your cutoff voltage so the charger does not reject the cells because they were too far discharged (and if that happens how to restore the cell easily so it will charge.)

They also have a built-in circuit board that prevents them from being too badly damaged, though IIRC most e-bikes are brushless motors so you will still need your own speed controllers. If you got one of the cheaper tools like the floodlight that runs off this battery pack, you could chop into it to tap the power post socket, and that way get a fully compatible socket so it would be easy enough to change batteries without stopping the bike and then you would not have to mess with creating a parallel array if you were at 36V.

I've been thinking of picking up some of the 36V tools as well as some of the smaller Black and Decker tools that use the same cells (VPX series.) If I do maybe I'll see about adding a chain drive that can be attached to the drill chuck to a bike, for laughs -- Dewalt e-bike without invalidating your Dewalt warranty :-)

[Trillo]

7. You just pressed on of my pet-peeve buttons.

I have a similar battery pack on a cordless drill, and I took it apart. I forget how many rechargable batteries it had inside, maybe 6 or 8 (12-volt drill), each was approximately the size and shape of a "C" battery.

I researched the type and cost of just those rechargeable batteries. Buying something like a whole shipping crate of them (not realistic for my use), the cost for each battery was about 25 cents.

The cost for a whole replacement module, at the time, from the local hardware store was $35.00 + tax, and that was not the "long lasting" module, which was costlier.

Hmm. Less than $2.00 worth of batteries for only $35.00. Only in America, where a sucker is born every minute, or so says P.T.Barnum.

What a great biz! Just make the battery module sealed so the batteries inside cannot be replaced singly as in most flashlights. Bet that pays for some SUVs and McMansions.

[skids]

9. Yeah for the old NiCd packs they are such a scam. Not in this case though...

...in this case the pack is actually cheaper than the individual cells bought direct from the manufacturer. Plus it has battery protection circuitry in it to prolong the life of the pack. (See my other response up above.)

[happyslug]

11. The chief problem with Lithium batteries is they are still batteries

The problem with most batteries is they take 4 watts of power to hold 1 watt of output. In small, low use power objects like cell phones and most electronics, this is a minor problem. In something like a car, it is the major problem.

Now most hybrids today, use a gasoline engine with Lead batteries. Lithium batteries can make the car lighter and thus more efficient, but even the Prius only goes about 20 minutes before the batteries have to be recharged (i.e. the engine turns on). The hybrids get their fuel efficiently from being able to use a significantly smaller and more efficient engine, that is gear to generate electrical power, with the batteries providing extra power as needed.

In conventional automobiles, the gasoline engine propels the car. At certain times the engine has to provide excessive power (i.e. pulling out onto a highway). At other times that same engine is just running at a very low power output (Cruising down the road for example). The Hybrid takes this excessive power of the gasoline or diesel engine to charge the batteries. The batteries are then used to propel the vehicle when the gasoline engine is off. When the Batteries need charged the Gasoline engine comes back on again. When extra power is needed the engine is used fully and extra power is provided by the batteries. Thus the Gasoline engine does NOT have to be the same power as in a conventional car and the Hybrid would have very similar performance to a conventional car, but with a significantly smaller engine. The Smaller engine is offset by the Batteries, but together the car weighs about the same as a conventional car, but both working together you get overall better fuel economy for the gasoline engine is NOT needed all the time, and when it is operating any excess power is being used to charge the batteries which takes over when the gasoline engine is not needed for electrical generation.

I go into the details, for it is the gasoline engine that is the key to the Hybrid, for it can be smaller and operates more often at full efficiency then in a Conventional car, with its waste of having a large engine stay on even if full power of that engine is not needed. The batteries and generators are just ways to make the Gasoline engine more efficient.

Thus converting lead acid batteries to lithium will help a little bit, but the weight difference is NOT that much, given that the sole purpose of the batteries is to provide about 30 minutes of drive time. After 30 minutes even the lithium batteries will need charged and will be charged by the Gasoline engine.

One of the problem is what if it was possible to use a engine to its full capacity without making the car a hybrid? That is possible, but it requires the car is sacrifice top end performance. This is what VW did with its Lupo, which was even better than the Prius when it came to fuel economy, but was NOT marketed in the US so VW could NOT make that claim in the US (Only EPA fuel numbers can be used in the US and the Lupo was NEVER even tested by the EPA for VW had no plans to market it in the US). The Lupo was a small car with an small engine, that operated when needed, but turned off when not even if the car was in motion. This system increased fuel economy even more than a Hybrid, but at the cost of decreased performance (i.e. no capably of 50 mph driving, the engine did NOT produce that much power).

When I did research on this issue a few years ago, the problem was NOT the batteries, but the whole concept that you had to have a car that can do 104 mph (Gore's son drove his car that fast last spring when he had a run in with the Police). A Lupo could NOT go that fast, but do you really need to go that fast? Do you really need to have the Capability to go that fast? I do not think so, but then I ride a 80cc Motor Scooter that gets 90mpg while I drive it on the local highways up to 45 mph (Through on the local mountains, I live in Appalachian Mountains of Pa, that top speed drops to 20 mph). It gets me where I am going, it uses its maximum power to get me there. The motor scooter is operating at maximum efficiency do to its small engine. The engine has no extra power, no matter how hard I try its will NOT go over 50 mph even down Chestnut Ridge.

Thus the problem with cars is NOT the efficiency of the batteries or the weight of the batteries, but the size of the Diesel or Gasoline engine it is combined with. The engine in the Prius is NOT the most efficient for it has to be able to go 104mph. That speed capability comes from a large engine and that means weight. My 80 cc Honda weighs 167 pounds, the Prius just under 3000 pounds. I get 90 (and that includes going up and down my local mountains), the EPA says the Prius gets 45 mph (Actual Mileage is generally less, but in the case of the Prius not as much as other cars the EPA test). Also note my 90mpg is my ACTUAL mileage NOT EPA (EPA does not test motor bikes for the simple reason the weight of the driver can vary the mileage, people who eight less than my 80cc gets over 100 mpg on it). The lithium battery will NOT help this situation. The weight saved will be under 100 pounds, the fuel economy increase will be minor.

When I did my research a few year back the small engine gasoline engine looked (and continues to look) like the better long term option. The decreased performance is more then compensated by the increase mileage and without the extra cost of having two engines, the Gasoline/Diesel and the Electric batteries. My 80 cc Motor Scooter cost me only $2000, the Prius is about 10 times that figure. Most people use their car primarily from home to work, thus the fact the Prius has seats for three that is rarely used a minor problem. That the Prius is a car and thus protects the driver from the weather is a plus on the side of a Hybrid, but I like driving my Motor Scooter even in winter, so a small plus at best.

My point is simple, there are ways to improve efficiency without going to hybrids, those require more sacrifices then most people want to do today, but are doable. The problem is that today Hybrids use their batteries in such a way that switching to Lithium will NOT improve fuel economy by that much, for the saving in weight is not that great given how Batteries are actually used in Hybrids. Converting to Lithium will provide some improvement, but no where near as much as a decision to cut down the size of the engine in today's cars.

[kristopher]

12. Perhaps you could opine on this

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=115x164561

The difference with your summary is significant, don't you think?

Isn't it possible that your research focused too much on the hybrid idea and not enough on a much lighter battery EV; *and* that the two are not similar enough to apply your conclusions about hybrids to EVs?

And doesn't that, in turn, sort of negate your entire argument?

I think it does.

[happyslug]

17. My research, which I admit is dated, was on what was best AT THAT TIME.

Lithium, other then as a battery for electrics, has only recently even been thought of, but my concern is NOT lithium batteries themselves, but the restriction imposed when using a battery. The Nano-safe battery looks interesting and may be the wave of the Future but right now today is still nothing more then an expensive toy. A good comparison would be to the early pre-1900 automobiles. Toys more than practical means of transportation.

For comparison lets look at pre-1900 Automobiles. This is the pre-carburetor days, so fuel usage was way higher then with the Carburetor (The Carburetor made the Gasoline engine usable, prior to it, the preferred car was the stanley steamer or the early battery electrics). Around the same time as the Carburetor was invented a Automobile show was held in New York, after the show most people opinion was the best wheel for the automobile was a solid steel wheel. Bicycles had had pneumatic tires for about 20 years, but no one could figure out how to make one that did not go flat on almost every car ride. This was solved by separating the inner tube from the tire itself (bicycle tires did not do this till the 1920s). With the inner tube INSIDE a rubber tire, the rubber tire could take all the beating from the road, and inner tube would stay inflated. Now with the steel wheel you did NOT have to worry about flats, but you were restricted to about 25 mph. Only the Pneumatic tire could go faster (And I should say, steel tire stayed "competitive" with the pneumatics till just before WWII, when the speeds on most US roads went up with the highways being paved).

Notice the Gasoline engine itself was NOT the problem with the delay of it adoption. The Gasoline engine had been used as early as the Civil War and the "Otto" engine (Which is what ALL inline. V-6s, V-8 and even the V-12s engines of today are based on, the rotary gasoline engine is the only big exception) had been invented in the 1880s. it took the invention of the Carburetor and the pneumatic tire for Cars to take off. Then and only then did the US (Stating in New York State in 1905) came up with a way to improve the roads cars would operate on, by taking gasoline (and even then it took till 1926 for the first road across the US to be paved, i.e. US 30, and even as late as the 1950s you had unpaved dirt roads used as major roads i.e. a "US" highway).

When it comes to Electric Cars the above shows part of the problem, how do we adjust our highway system to deal with battery electric cars? Given the main problem with Batteries is the 1 for 4 energy lost (i.e. for every FOUR WATTS of power that goes into a Battery you get only one out) a better solution may be a direct wire hookup (Like the old Streetcars). Even in that type of system you have electrical lost as you move from where the power is being produced, but even as early as 1900 that had dropped to about 10% loss (Which seems to be the loss even today). If energy cost remain high, and I think they will, the difference is tremendous (and the fact a direct wire system does NOT have the added weight of Batteries make them even more energy efficient, which is why the Streetcars stayed competitive till Gasoline hit 25 cent a gallon in the 1950s). A further factor in favor of Streetcar was that Steel Wheel on Steel Rail produces way less friction, and thus uses less energy, then rubber tire on concrete or asphalt. Yet with all these advantages, the Streetcar could NOT compete with the gasoline engine as the price of gasoline dropped in the 1930s, 1940s, 1950s and 1960s.

Maybe its my world view, I can NOT get over the 4 to 1 power loss AND that the Electrical Car will have to haul its own batteries along with the rest of the Car AND use Rubber tires on Concrete. In an ear of high Energy Costs, streetcars start to look better and better and it is that comparison where I see Electric Cars failing.

Do to the above advantages I see the Interstate Highway system being converted to a direct wire system 20-30 years AFTER Peak Oil sets in, just to run trucks using a cheaper from of power. Once the Interstates are electrified I see a push to put steel rails on them do to Steel's lower friction rating. Now I foresee the Railroads electrifying within ten years of peak and a reduced traffic load on the interstate for that reason, but once truck traffic dropped the trucking firms will be demanding a "solution" to their problem i.e. high oil costs. The best solution would be a electrification system and then a rail system for "Express" service the truckers have been performing since about WWII. The exact integration with the Railroad will be resolved on a case by case basis, but the Interstate system exists and conversion will be cheap compared to continuing the present system (Which will be unavailable within 20 years of Peak).

Thus the problem may be my background, I do NOT see electric cars, or any other vehicle, of the future i.e. 10 years after peak oil, as doing much better then horse drawn vehicles or bicycles. Such Vehicles, as to speed and distance, while non-competitive when it comes to long distance transportation can dominate short haul trips. This speed drop has more to do with designing cars for the lightest engine possible even if that means decrease performance. How fast do you need to go if your trip is less than 20 miles? 20 mph may be fast enough, given that to go faster would require a doubling of the energy required. My problem I just do NOT see society valuing speed over the cost of that speed if the costs of the speed is high. Thus I do NOT see Electric Cars, 20 years after peak, or any other car, having a top speed is excess of 25 mph. The cost savings in just the weight of the engine and/or batteries will be enough to keep the size of the Car down. Thus short charging times may NOT be needed, since the vehicles will be used for short hauls only. Only time will tell if my presumptions of the Future will be correct, but if it correct most research on Electric Cars that go faster then 25 mph and lasting more then four hours may never be needed.

[kristopher]

18. Where are you getting this 4/1 in out ratio from? It's completely wrong.

[IDemo]

19. The equation was misstated

"for every FOUR WATTS of power that goes into a battery you get only one out." - wrong

Battery charging and discharging itself is actually a pretty efficient process. The total well-to-wheel number, using a coal burning power plant, would put it closer to between 3 and 4 Watts in/1 Watt out:

Electricity Generation -- 39%
Transmission Lines ----- 95%
Charging -------------- 88%
Vehicle Efficiency ------ 88%
Overall Efficiency ----- 29%

Tesla is claiming slightly better charging and vehicle efficiency numbers.

[kristopher]

20. Everything in those posts is of dubious value.

"...
Lithium, other then as a battery for electrics, has only recently even been thought of, but my concern is NOT lithium batteries themselves, but the restriction imposed when using a battery. The Nano-safe battery looks interesting and may be the wave of the Future but right now today is still nothing more then an expensive toy. A good comparison would be to the early pre-1900 automobiles. Toys more than practical means of transportation...

Lithium batteries are more than 30 years old and represent a 'mature' technology.

I understand that both charging and vehicle efficiency are (well) above 90% now. And if you factor in the replacement of thermal generation by renewables that use battery electric drive vehicles as storage with V2G technology, the overall system efficiency (well to wheel) comes very close to 90%.

An important point overlooked by the analysis falsely claiming batteries only deliver back 25% of their input is that an internal combustion engine, whether it us used to generate electricity to charge batteries or to provide mechanical power to the wheels is still going to lose most of its input energy to heat (like the coal plant). The boundaries of that analysis are so muddled it is really something people should be warned to question.

[IDemo]

21. V2G will certainly be a big part of the transportation solution

But it's an aspect of the system that can't be factored into the well-to-wheel equation, which simply defines the ratio of energy delivered to the rear (or front) wheel versus the energy content of the original source.

from Tesla:

To compute the well-to-wheel energy efficiency of any car, we start with the energy content of the source fuel
(e.g. crude oil or natural gas) as it comes from the ground. We then track the energy content of this fuel as it is
converted to its final fuel product (e.g. gasoline or electricity), subtracting the energy needed to transport the fuel
to the car. Finally, we use the fuel efficiency of the car itself (e.g. its advertised mpg) to complete the equation.
http://www.evworld.com/library/Tesla_21centuryEV.pdf

Energy delivered to the grid via V2G is energy not used to drive the vehicle. If you take into consideration the dollar value of that energy and other ancillary services that V2G can provide, the energy costs can be further offset for an EV owner. But the actual efficiency itself will remain the same.

[kristopher]

24. I definately wasn't clear...

I wasn't including the benefits of V2G in the system efficiency number for the car; I was just proceeding from the normal assumption that the renewable electricity generated suffers virtually no thermal loss and is going directly to the the end user via grid.

However, if we were to set the boundaries in a manner comparable to the one you used from coal to wheels, then there are losses in a renewable system that isn't storing energy generated in excess of demand. That is the often unstated flip side to the renewable's most often noted deficit, lack of dispatchability. It is also why V2G is such a meaningful contribution to a cost effective system based on renewable power sources.

[Howzit]

23. No need for cars to exceed 25 MPH?

You can do better than that on a bicycle, or are you going to pass a law prohibiting cyclists from wasting food energy by exceeding that speed unless they are clinically obese? :)

I travel so little cumulatively that I battle to use a tank of gasoline a month. Still, I keep track of average speed and MPG just for grins. I find that when my average speed drops below 30 MPH my average MPG drops below 25. The less time I spend standing still at traffic lights or bogged by slow commuters, the higher my MPG. Frequent acceleration and (non-regenerative) braking is the real MPG killer. As I stated in my other response to your post, my car averages 30 MPG at an average of 80 MPH - not bad for old technology.

[happyslug]

25. You must drive an automatic, they up and down shift all the time

This is especially true of 25-35mph range, and why getting over 35 is important if you have an automatic. Manual transmission just buck at about 25 mph, they only shift if the operate does the shifting. Thus Manuel transmissions get must better fuel economy at that speed then automatics.

Anyway, the best way to improve the fuel economy of automobiles is to make then lighter, the problem is in the 1970s most cars were re-designed to be as light as possible, th problem wa the main remaining weight was in the engine and transmission (along with the rest of the power train). The only way to reduce these weights was to cut down performance (Thus the death of the Muscles cars of the 1960s). Even then the desire was to keep the car capable of 70mph, the design spec for the Interstate Highway system. Even the Prius was designed to operate at this speed. To get better fuel economy means to further reduce the weight of the car and that means attacking the power train.

Thus what I see in the future, smaller engines, which means lighter transmissions and power trains. This is what VW did with the Lupo, Small engine, light transmission, light drive train. The side affect will be much lower speed, about 25 mph (Remember the "average speed on a LA freeway during rush hour today is only 13 mph). I do NOT see the speed limit dropping that low, I just see the cars being restricted to having engines only capable of that speed. I remember reading in the 1970s on Popular Mechanics from one of their writers on cars was they was no reason for anyone to be driving a car with an engine over 2.5 liters. That was a big enough engine for 50+ mph service (The Prius has been know to go up to 104 mph, look up Gore's son's arrest for details). Given that situation I fully see the US converting over to the Micro-cars that exist in Japan and Europe. Such cars have engines BELOW 1.0 liter and are NOT expected to go over abut 25-35 mph.

The problem is the US and the rest of the World has hit a brick wall when it comes to improving fuel economy, most of the easy methods were adopted in the 1970s, with electronics providing most of the improvements since 1980 (And much of these electronic "improvement" were computers designed to give the car the best fuel economy on the EPA tests, not in real life). Thus to get better real fuel economy the size of the engine, transmission and the rest of the drive train has to go dow. With that down swing so will performance. Thus my comments about 25 MPH, that will NOT be a product of any speed limit but the real speed limit caused by the fact most cars will NOT be able to do better then 25 mph.

Please note I am talking about what a car can normally do, VW once built a test car that traveled on the Autobahn and did 235 mpg, the driver said the car drive well but refused to say how long it took to get to its highest speed on the Autobahn. The technology is for much lower speeds, but that does not mean under the most favorable conditions the cars of the future will be incapable of higher speeds. The speeds I am talking about is the speed most people will be traveling NOT a theoretically maximum, thus my use of 25 mph for at that speeds most manual transmissions get their best fuel economy today and I expect that to still be true in the future.

[Howzit]

26. At 46, I still consider automatics boring

I live in Southern California and drive a stick shift - have never owned an automatic, but then I grew up in a foreign country.

My car grumbles if I try to drive much under 50 MPH in top gear and I certainly am not going to lug it at 25 MPH because you believe that provides the best MPG. If I need to crawl at 25 MPH I would be in third gear at 1600 RPM and get about 35 MPG; no better than 50 MPH in top at 2000 RPM.

Fuel consumption increases with speed as a function of drag rather than weight - that is one reason why your scooter only get double the MPG of a Prius. Weight is a big factor with frequent acceleration and braking. The Prius weighs almost 3000 lb because of its batteries and US crash safety standards. It could easily be made lighter if it didn't have to meets US crash standards: Small cars are popular in Europe because of fuel cost and highly populated narrow streets, but available because the crash safety standards are lower than those applied in the US. The '83 VW Rabbit sold in the US weighed less than 2000 lb, but would not meet current US crash safety standards.

More and more engines are being made with aluminum or even magnesium blocks rather than cast iron to save weight. Remember that an engine's performance comes largely from its displacement: the bigger the holes the more power, and holes don't weigh anything. Sure, bigger pistons and a longer stroke increase the loads on the other components, forcing them to be heavier, but it takes proportionately less material to make a large engine stiff than a small one.

The principle is one everybody is familiar with:

A common foot long ruler of about 1 1/4" wide by 1/8" thick is 1000 times stiffer when bent across its width compared to across its thickness. Now imagine 4 such rulers bonded together forming a hollow tube - it would be very rigid and equally stiff in all directions. Bonding the 4 rulers into a solid 1 1/4"wide by 1/2" thick would increase the stiffness by a factor of 4 across the width, and a factor of 64 across the thickness compared to a single ruler. Thus the sold stack would be twice as stiff as the hollow tube in one axis, but only 1/15th as stiff in the other (much less).

I can see the top speed capability of cars coming down to below 100 MPH, but not to 25 MPH. You could make it pedal powered and beat 25 MPH. A car that could only do 25 MPH on the level would need the passengers to get out and push at every hill...

[Howzit]

28. The reason automatics downshift at 25 MPH is

because that is the only sensible thing to do. Forcing an engine to work hard at low speed may improve efficiency up to a point, but there is a large difference in lubricating oil film thickness between 800 and 1500 RPM. I think by running around at 25 MPH in top gear you are looking at an engine rebuild that is going to cost more than any fuel you think you have saved. When a car bucks at low speed in high gear it is trying to tell you something: "please don't do it". Then there is the safety aspect: You won't have any acceleration at such low speeds should you need to get out of the way of another vehicle.

Nothing about the modern car was optimized for 25 MPH. The suspension on European cars especially feel harsh at low speeds on anything but glass smooth roads. My European car's ride settles down at 80 MPH and was designed for cruising flat out in safety on the Autobahn. A car that has a good ride at 25 MPH would most likely have sluggish and even dangerous handling at double or triple that speed - think your typical American barge.

The European formula for efficient cars is: small frontal area, low mass and reasonable performance from a small engine. Instead of needing to slow down for every bend and curve, these cars handle better than the typical American car (optimized for ride) and can carry speed though bends. This eliminates the need for powerful engines because it only takes a small engine to maintain good cruising speeds.

Obviously you are a happy slug at 25 MPH, but you must realize that some people have less time and longer distances to cover than you do. These crazy people are chasing money for themselves, but pay the taxes that fund the social programs people like you dream up. Perhaps you would be happier with this kind of vehicle: http://www.bostondynamics.com/content/sec.php?section=BigDog

[Howzit]

29. Not to belabor the point, but if manual cars were optimized for MPG at 25 MPH then

they would all have heavier flywheels to smooth them out for such slow running. Heavy flywheels would make the cars sluggish to accelerate in lower gears when engine speed changes are the largest.

You should research octane ratings and the effect of knock at different engine speeds. You might notice that engines ping or knock easier at low speed than higher speed fundamentally because the piston is moving out of the way of the increasing pressure at higher RPM. AT low RPM, the piston is "in the way" and the resultant pressure spike can cause pinging or end-gas detonation (knocking). Engine management responds to pinging by retarding the ignition timing, but this reduces thermal efficiency. You can offset this loss by using higher octane fuels, but why not just use a lower gear?

My remarks about MPG achieved with my car are with California blended 91 octane. The lack of low speed economy would be much more noticeable with regular gas and with my car, can be felt as a loss of torque below 3000 RPM.

If you think I am making this up, consult an SAE manual such as: http://books.google.com/books?id=ESHYjZ0CxwUC&dq=internal+combustion+engine+handbook page 226 shows how oil films form in bearings as a function of engine speed...

[Howzit]

30. Stribeck curve shows effect of engine speed on lubrication

http://www.tribology-abc.com/abc/stribeck.htm


http://www.ornl.gov/~webworks/cppr/y2005/pres/117987.pdf search for the word speed on page 6 to see the relationship with wear:

Too low speed is not good. It increase friction and wear. Friction eats efficiency. Wear eats the engine.

[kristopher]

32. Hmmmmmmmmmmmmmmm.....

&usg=AFQjCNE1vzLud7XCxq-Li01xb1E-pwBgHA

[Howzit]

33. If you had a Tesla, would you keep it down to 25 MPH?

Sure, there is no energy efficiency penalty for it, but if faced with an open road with no pedestrians around, why would anyone travel at only 25 MPH?

[kristopher]

34. Hmmmmm II

"...would you keep it down to 25 MPH?"

Whenever I'm in the garage, you have my word on it.

Other link seems broken:
Graph comparing Internal combustion engine with electric motor:

[Howzit]

22. Difference between MPG and efficiency

You really like your scooter and you like to compare its efficiency to a Prius. Consider that the Prius weighs 2900 lb and your scooter about one tenth of that. Yet the Prius achieves "only" 1/2 to 1/3 of your scooter's MPG. Doesn't that make the Prius much more efficient than your scooter, despite its ability to exceed 100 MPH? Add its people and load carrying capacity and we have a clear winner.

Smaller engines that are kept closer to their max efficiency load range obviously contribute to fuel economy, but it is the Prius's regenerative braking that boosts its real world MPG the most. This benefit applies mainly to "stop and go" driving, as the brakes shouldn't be used much on a highway. This is reflected in the Prius's 48 / 45 MPG city / highway EPA rating.

The Prius's 45 MPG highway rating is achieved by means of its 1.5 liter engine working fairly hard and other factors such as good aerodynamics and narrow low rolling resistance tires. My car has a 3 liter engine and averages a real 30 MPG, cruising at 80 MPH between cities, and about 35 MPG at 55 MPH - better than one might expect at higher road speeds and worse at lower speeds. Despite this mediocre performance I have no yearning for a car with higher MPG as I drive less than 5000 miles a year.

When it comes to vehicle choices, there is no one-size-fits-all answer - as they say, your mileage will vary:

Fuel consumed = average MPG x miles traveled, not just MPG.

Efficiency = useful work performed / fuel consumed

Useful work performed = miles traveled x (number of people + mass of cargo carried)

[Howzit]

31. The VW Lupo couldn't reach 50 MPH?

Must be broken: http://www.jpoc.net/dotorgsite/jpocorg/cars/roadtest/lupo2.html

http://www.google.com/search?hl=en&q=vw+lupo+%22road+test%22

[monomach]

13. Hybrids still use too much gas to be acceptable for our long-term future.

Plug-in all-electric is the future.

[Bruce McAuley]

16. A friend put a gas motor on his bicycle for range...

It works on the old Velosolex principle of a friction drive to the tire, either front or rear. He bought a 37cc four stroke motor and kit to position it over the rear tire. I haven't heard if it's working well yet, but no reason it shouldn't.
I'm envisioning something in a bicycle/small motorcycle size with a battery drive like my ebike but with a small motor/generator that could put out just the 450 watts my electric motor needs, or even something slightly larger that would move both myself and my wife to the grocery store or post office here in town. Plug it in overnight, use the battery for most of the early driving then have the motor switch on automatically when it senses the battery draining too far.
For 2 people who both weigh 200 pounds I could see a light framed 3 or 4 wheel bicycle framed and wheeled vehicle that weighs only 300 or 400 pounds at the most for a bare rolling chassis without fairings, etc, but including the small motor/generator, batteries, and drive motor.
Am I just dreaming here?

Bruce

[lfairban]

27. Someone called this a Tri-bred.

You may wish to read:

http://www.motoredbikes.com/showthread.php?t=13517

http://www.motoredbikes.com/showthread.php?t=11754

http://www.motoredbikes.com/showthread.php?t=8764

The best idea is to use a regenerative hub motor and a friction or direct drive gas engine.

From a practical standpoint, it would be good to be able to remove the gas engine for short trips. Another idea is using a small generator. It could be carried on long rides, and could be shared among more than one user, just hand it off.