[carve]

Has everyone seen the announcement that the new Volt will get a 230mpg city rating? That's outstanding. My only question: how much energy is in a gallon of electricity?

[Bobby_Light]

Link please.

[quagmire]

http://media.gm.com/servlet/GatewayS...=2&docid=56132

[carve]

In case you didn't catch my drift, there's no such thing as a gallon of electricity. The number is therefore completely arbitrary, but I'm sure it'll fool a lot of people. I'm sure GM was able to use many of it's gov. connections it now has to get a great mpg to help them in their CAFE ratings so they can sell these at a loss, and sell more low-mpg cars at a nice profit.

[Bobby_Light]

Originally Posted by carve

In case you didn't catch my drift, there's no such thing as a gallon of electricity. The number is therefore completely arbitrary, but I'm sure it'll fool a lot of people. I'm sure GM was able to use many of it's gov. connections it now has to get a great mpg to help them in their CAFE ratings so they can sell these at a loss, and sell more low-mpg cars at a nice profit.

I caught it, but that number is eye catching.

[quagmire]

Originally Posted by carve

In case you didn't catch my drift, there's no such thing as a gallon of electricity. The number is therefore completely arbitrary, but I'm sure it'll fool a lot of people. I'm sure GM was able to use many of it's gov. connections it now has to get a great mpg to help them in their CAFE ratings so they can sell these at a loss, and sell more low-mpg cars at a nice profit.

I doubt it as others who produce plug in electric vehicles, will be tested the same way....... So GM has no advantage besides being the first one to produce a vehicle like the Volt.

[carve]

I just ran some numbers. The volt has 8 kwh of useable electricty in its battery. They expect it to go 40 miles on that, although it wouldn't surprise me if it couldn't go that far in EPA tests.

A gallon of gas contains 36.6 kwh of energy, so the battery contains the energy of about .22 gallons of gas.

40miles/.22 gallons = 182 miles per gallon. An electric drive train has about 4x the efficiency of a gas engine, so, for an estimated reality check, this would be like 45.5 mpg on gas. Reasonable. However, their official RATING, is far better than even their best case scenerio of 183 mpg! They just pretend like it's getting infinity mpg until the generator kicks on. I mean, it is, but mpg isn't a relevant number if your fuel isn't a liqiud. 45 mpg would be a rating that'd much better reflect reality.

Since we'll be seeing more Hybrids, maybe we should measure how far they go on a given amount of energy instead of a given volume of fuel. Just replace gallons of gas with 36.6 kwh. That would show Ethanol's true self, too, since it only contains about 70% as much energy per gallon as gasoline. Or better yet, how much energy it takes to go a given distance- kwh per 100 km would be good. Then you'd have to throw in some waiting factors based on the costs of different fuels, which would always be changing.

[Couch]

I was confused to. But most people reading the story would never think about stuff like that because they're slow. lol just kidding.

Maybe their 230mpg = per charge?

[quagmire]

Originally Posted by carve

I just ran some numbers. The volt has 8 kwh of useable electricty in its battery. They expect it to go 40 miles on that, although it wouldn't surprise me if it couldn't go that far in EPA tests.

A gallon of gas contains 36.6 kwh of energy, so the battery contains the energy of about .22 gallons of gas.

40miles/.22 gallons = 182 miles per gallon. An electric drive train has about 4x the efficiency of a gas engine, so, for an estimated reality check, this would be like 45.5 mpg on gas. Reasonable. However, their official RATING, is far better than even their best case scenerio of 183 mpg! They just pretend like it's getting infinity mpg until the generator kicks on. I mean, it is, but mpg isn't a relevant number if your fuel isn't a liqiud. 45 mpg would be a rating that'd much better reflect reality.

Since we'll be seeing more Hybrids, maybe we should measure how far they go on a given amount of energy instead of a given volume of fuel. Just replace gallons of gas with 36.6 kwh. That would show Ethanol's true self, too, since it only contains about 70% as much energy per gallon as gasoline. Or better yet, how much energy it takes to go a given distance- kwh per 100 km would be good. Then you'd have to throw in some waiting factors based on the costs of different fuels, which would always be changing.

That's the issue. Unlike the Prius being a parallel hybrid where it is still easy to use the EPA's current method of testing, the Volt is a series hybrid where the ICE won't be running all the time. So how do you test it? I wish I knew the way the EPA got the 230 MPG number......

[sparkyg]

Originally Posted by Couch

I was confused to. But most people reading the story would never think about stuff like that because they're slow. lol just kidding.

Maybe their 230mpg = per charge?

This could be the truth, maybe driving the car per the EPA ratings system and that's how far you go.

I am sure they used the rating system to their advantage any way you look at it.

[NewSong]

The Chevrolet Volt, on other hand, runs on electricity that comes from two sources -- a battery as well as a gasoline engine.

When gasoline is providing the power, the Volt might get as much as 50 mpg. But that mpg figure would not take into account that the car has already gone 40 miles with no gas at all.

So let's say the car is driven 50 miles in a day. For the first 40 miles, no gas is used and during the last 10 miles, 0.2 gallons are used. That's the equivalent of 250 miles per gallon.

[atr_hugo]

The Volt is all electric for the first 40 miles (that'll run the battery charge to about 50%) at which point the extended range gas engine will power the electric motor (it will NOT recharge the batteries).

So how did they come with the 230 mpg #? Well they had to run more than 2 EPA driving cycles to activate the 'extended range' engine. It was .22 gallons for about 50+ miles. Here's a linkee: http://www.greencarreports.com/blog/...ng-assumptions

My big question is this, will running on the 'extended range 1.4L engine feel like driving a car in limp-home mode? ; -)

[carve]

It gets 40 miles per charge MAXIMUM. Nowhere near 230 miles. The MPG rating problem isn't because it's series- it's because it's a plug-in. Much of it's energy comes from somewhere besides the gasoline, but it still uses energy. It's like having a 45 mpg econo car that starts the day with a gallon of gas (.23 x 4 times as efficienct as an IC drivetrain.

Don't get me wrong here- electric is the future, and plug-in is a good stop-gap or road-trip solution. I just don't like the way they're fudging the numbers. According to this, the Tesla, or even a Volt if it could complete the test on battery power alone, could be advertised as getting infinity mpg. I also don't particularly like the way the volt is set up.

The internal combustion motor is a lot of dead weight 90% of the time for 75% of people. The generator duplicates a very expensive part (the motor can already be used as a generator) and it CAN'T EVEN CHARGE THE BATTERY. That's righ- in gasoline mode, the generator powers the electric motor directly and can't charge the battery, and it can't provide as much power as the battery does either. Dragging around this extra dead weightrequires an extrodinary amount of current from such a small battery pack. To avoid catching on fire, you need a bigger, heavier, more expensive high-current battery. If they'd gotten rid of the generator and use a much smaller gas engine, they could've spent the same amount of money, used a slightly bigger battery pack that'd provide massively longer range and draw less current from each cell, which allows them to optimize each cell for energy density rather than power density.

I think an ideal range-extended EV would have a battery good for 100 to 200 miles. In normal commuting, you'd keep the state of charge between 33 and 66%, maximizing longevity. The electric motor would power the front wheels, maximizing regenerative braking. When taking a road trip there'd be a very small, possibly removable (in place of a battery?) internal combustion engine mounted to a CVT that could power the rear wheels. This would make little more power than required to maintain 75 mph on the highway...maybe 20 hp. On a long trip, you'd charge up to 100% at night and use that energy to provide most of your accelerating and hill climbing power. The gas motor would be used to give you the bulk of your range, adding little weight and burning little fuel. You'd also get an EXTRA 20 hp in range extended mode, rather than reduced power. At times when you're going less than 75, the front wheels could go into regen-mode and top up the battery. This would be better and likely cheaper than the Volt in every way. Better longevity, longer range, always running at full power, and uses a small, light motor + CVT instead of a big motor and big generator. Ideally, since back-up power would seldom be used, the engine could be optimized for affordibility, light-weight and simplicity (air cooled?) rather than for power, emissions, or even long-term reliability (will probably only go ~40k miles in it's life for most people). Maybe emissions requirements could be more in line with gas power generators, or recreational equipment.

The volt just doesn't seem that well thought out, and seems like an enormous amount of money for what'll amount to a Chevy-Cruze quality econo car with better efficiency.

[blue2fire]

It's a Chevy, guys. Who cares, right?

Anyway, didnt BMW think of this and put it into production a century ago?

[quagmire]

Originally Posted by blue2fire

It's a Chevy, guys. Who cares, right?

Anyway, didnt BMW think of this and put it into production a century ago?

Think you're going to gain support by being an image snob?

Originally Posted by carve

It gets 40 miles per charge MAXIMUM. Nowhere near 230 miles. The MPG rating problem isn't because it's series- it's because it's a plug-in. Much of it's energy comes from somewhere besides the gasoline, but it still uses energy. It's like having a 45 mpg econo car that starts the day with a gallon of gas (.23 x 4 times as efficienct as an IC drivetrain.

Don't get me wrong here- electric is the future, and plug-in is a good stop-gap or road-trip solution. I just don't like the way they're fudging the numbers. According to this, the Tesla, or even a Volt if it could complete the test on battery power alone, could be advertised as getting infinity mpg. I also don't particularly like the way the volt is set up.

The internal combustion motor is a lot of dead weight 90% of the time for 75% of people. The generator duplicates a very expensive part (the motor can already be used as a generator) and it CAN'T EVEN CHARGE THE BATTERY. That's righ- in gasoline mode, the generator powers the electric motor directly and can't charge the battery, and it can't provide as much power as the battery does either. Dragging around this extra dead requires an extrodinary amount of current from such a small battery pack. To avoid catching on fire, you need a bigger, heavier, more expensive high-current battery. If they'd gotten rid of the generator and use a much smaller gas engine, they could've spent the same amount of money, used a slightly bigger battery pack that'd provide massively longer range and draw less current from each cell, which allows them to optimize each cell for energy density rather than power density.

I think an ideal range-extended EV would have a battery good for 100 to 200 miles. In normal commuting, you'd keep the state of charge between 33 and 66%, maximizing longevity. The electric motor would power the front wheels, maximizing regenerative braking. When taking a road trip there'd be a very small, possibly removable (in place of a battery?) internal combustion engine mounted to a CVT that could power the rear wheels. This would make little more power than required to maintain 75 mph on the highway...maybe 20 hp. On a long trip, you'd charge up to 100% at night and use that energy to provide most of your accelerating and hill climbing power. The gas motor would be used to give you the bulk of your range, adding little weight and burning little fuel. At times when you're going less than 75, the front wheels could go into regen-mode and top up the battery. This would be better and likely cheaper than the Volt in every way. Better longevity, longer range, always running at full power, and uses a small, light motor + CVT instead of a big motor and big generator.

The volt just doesn't seem that well thought out, and seems like an enormous amount of money for what'll amount to a Chevy-Cruze quality econo car with better efficiency.

How much do you want to bet how much that will cost using a battery that can last 100-200 miles? Certainly not $40K......... By having the ICE be a generator, it can run at its peak efficiency all the time. As you pointed out, the ICE can't charge the battery enough to keep it at 30% and drive the car. So the only other choice was to have the ICE run the electric motor. There is going to be a solar panel roof option according to Lutz that will help charge the battery.

[My135]

They should rate it miles/kwh and hours to fully charge instead.

[blue2fire]

Originally Posted by quagmire

Think you're going to gain support by being an image snob?

It seems that being a snob and basing comments on no truths whatsoever is the ticket to social acceptance here.

[atr_hugo]

Originally Posted by blue2fire

Anyway, didnt BMW think of this and put it into production a century ago?

You may be thinking of the Lohner-Porsche?

[carve]

OK...Elon might skew the numbers, but he's probably in the right ball park. Here's what he says...

Originally Posted by Elon Musk

An important consideration that people without a technical background don't understand is that you can either have a high power or a high energy cell chemistry, but not both. Since the battery pack in a plug in hybrid like the Volt has to generate the same *power* as a much larger battery pack in a pure electric vehicle, it has to use a low energy cell chemistry... The net result is that a 40 mile REV pack is roughly half the size of a 200 mile EV pack.

This means they had to optimzie for power density instead of energy density. They could probably get double the range for a battery 30-40% bigger, and offset that cost by shrinking the combustion powertrain.

If the ICE is designed for range, it's probably going to spend most of it's life going between 55 and 75 on the highway, so it can also be optimzied. The Volt motor can't be as optimized as you think because it can't take power from the battery and the engine at the same time. I predict driving it will feel something like a particularly slushy CVT when in range-extended mode. If it could put it's excess power back into the battery, then it COULD operate at max efficiency all the time. Since the battery can't contribute power to the motor at the same time as then engine (as in the Prius), the motor needs to be MUCH- MANY TIMES more powerful than would otherwise be required. It just isn't that elegent of a design.

[carve]

The solar panel is another gimmick. You have to put it in a vulnerable, non-optimal position, accelerate the extra weight around with you everywehre you go, and it'll make a negligable difference to power consumption. Look at those solar racers...they weigh maybe 500 pounds, have ENORMOUS multi hundred thousand dollar solar arrays, carry one 120 pound person in supreme discomfort with minimal safety equipment, and can still only manage about 40mph on a bright sunny day at high noon. A good rule of thumb is a one square meter solar panel, mounted in a fixed position OPTIMIZED FOR YOUR LATITUDE makes about 633 watt hours per day on a seasonaly-average SUNNY day. This panel would be pointing straigt up, so is only optimized if you live at the equator. Figure if you live at 45 degrees you'd get about half that much energy. This means on a seasonly-average sunny day (you'll get more in summer, less in winter), if you park in the sun the roof mounted panel, if it's as big as possible, may get you an extra 1.5 miles per day, minus whatever energy is required to haul it's weight around. If you live somewhere where cloudy days are common (most of the US), you'll get significantly less than that. The solar panel is a look-at-me-i'm-so-socially-conscious gimmick. It'd be cheaper and more efficient to put the solar panel on your house and sell the power to the grid during the day, and then charge the car with the cheap off-peak power at night.

The thing that'll really confuse people is this 230 mpg number though...even some of you seem to be falling for it. If you put a gallon of gas in the car, you'll not be able to drive anywhere near 230 miles. I hear it get on the order of 30 mpg in gas mode, but lets give it the benefit of the doubt and say it gets 40.

With a fully charged battery, to take a trip of 230 miles you'll need all that battery power and 4.75 gallons of gas. That's nearly 5x the amount of gas the number will lead people to believe. Your trip average will be slightly under 50 mpg. To come back to my first post, miles per GALLON is a meaningless number when your energy source is not measured in gallons.

[iatacs19]

Nissan Leaf: 367mpg

http://www.autoblog.com/2009/08/11/n...lent-for-leaf/

LOL

[carve]

Good site. I found this quote on it...

Originally Posted by autoblog

Under the new methodology being developed, EPA weights plug-in electric vehicles as traveling more city miles than highway miles on only electricity. The EPA methodology uses kilowatt hours per 100 miles traveled to define the electrical efficiency of plug-ins. Applying EPA's methodology, GM expects the Volt to consume as little as 25 kilowatt hours per 100 miles in city driving. At the U.S. average cost of electricity (approximately 11 cents per kWh), a typical Volt driver would pay about $2.75 for electricity to travel 100 miles, or less than 3 cents per mile.

OK...so they're using kwh/100 miles! AWESOME- just what I suggested. However, their mpg equivelent is based on fuel cost. It might be nice for a little piece of supplementary information, but the price of electricity can vary by hundreds of percent across the country, and the price of gas is very unstable, so this number becoming meaningless after a few months, and may be way off depending on where you live. Furthermore, it ignores the fact that the battery would probably need to be replaced much sooner than a motor, although the rest of the drive train would be lower maintenance. It also ignores that you don't pay road taxes when you use electricity, but you do when you buy gas.