CNN drives the Chevy Volt

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Originally posted by: heymrdj

Originally posted by: RU482

Originally posted by: Skoorb
What if the Volt did away with its batteries and just an array of capacitors with enough juice to take a full highway speed brake and through charging/discharging of those and the engine either on at 100% or off, we get a similar effect, so even at highway speed say you need 50 horsepower and the engine is making 150, it will turn on for 20 seconds to charge the capacitors and then off for 40 as they quickly drain out, then on again. I imagine it was considered or ignored outright (maybe capacitors are too heavy or useless for discharges as long as 60 seconds).

The only reason the batteries are really in the volt is so that a) it can be plugged in for short trips and b) allows the engine to be off or running at full power.

the last time I worked int he auto industry ( a few years ago) the reliability and safety of UltraCapacitors made sony LiIon laptop batteries seem awesome

I needed a good chuckle.

Just keep them in the trunk. Will ensure people are more careful not to rear-end you because to do so the back of your car turns into a bomb and shoots metal through their windshield.

 

[Bignate603]

Originally posted by: LTC8K6
Stop redesigning my vehicle.

Go design your own. This is my imaginary grant money.

I work with real grant money. Propulsion systems are my job, though I do design for aircraft, not automobiles. I'll leave you to your imaginary system and I'll stick with my turbines.

 

[91TTZ]

Originally posted by: Bignate603

So you'd have to let your car idle for a few minutes to charge up the capacitors before you left? Or would you just drive at 20 mph because your capacitors are out of juice because you accelerated hard and then coasted to a stop a few times between a series of stop lights? The engine would be too small to accelerate from a stop without the energy storage and capacitors have some serious drawbacks. .

No, the engine would still be big enough to drive the car on engine power alone. If a Prius's battery runs out, does it only go 20 mph? No. The car still has 76 HP. Not going to win any races, but you won't be holding up traffic, either. Hell, my first Toyota Corolla had less HP than that, and wasn't too much lighter.

 

[91TTZ]

Originally posted by: KnightBreed

Originally posted by: 91TTZ

Originally posted by: Skoorb
What if the Volt did away with its batteries and just an array of capacitors with enough juice to take a full highway speed brake and through charging/discharging

I agree that capacitors are the way to go. They're much cheaper than the huge batteries and they'd have just enough energy storage capacity to improve efficiency. They'd allow the car to get to highway speeds from a full stop and they'd store the electricity generated while braking.

Remember, you don't really need to be able to drive 40 miles on battery power to improve efficiency. The simple act of using caps to even out the load on the generator (engine) will help.

Improve efficiency by how much? How much gas will a cap save if it gets me up to highway speed, but I end up driving for 20+ minutes? The amount of electricity needed to get to highway speed is far more than you're going to get from stomping the brakes a couple times.

You can improve efficiency quite a bit by optimizing the engine to run in a narrower RPM range. One of the biggest complications in automobile engine design is that it needs to perform smoothly across a pretty wide RPM range. Usually the most efficient RPM is the RPM at which the engine produces max torque. You could cam it down so the torque peak doesn't occur so high in the RPM range.


The car would be drive by wire like some cars already have. The throttle wouldn't connect directly to the throttle body, it would connect to a throttle position sensor that tells the computer your demand. The computer would decide the most efficient manner to fill that demand, whether it be keeping the engine running in its max efficiency and letting the caps pick up the slack, or force the engine to rev up to supply more power.

The caps wouldn't be powering the electric motor alone. The gas engine would be producing enough power for cruising plus a little extra to charge the caps. They'd be used for supplying extra juice for the short periods of high demand to make up for the lackluster performance of the high-efficiency engine. My idea wouldn't have the gas engine shut off at all when you're driving.

Of course there are times when your throttle demands exceed what the engine can produce at its most efficient RPM. In those cases the engine would run outside its most efficient range until the demand decreases. That's where the caps would come into play. Since most of those burst of demanded power are only temporary, the capacitors could smooth out that demand by supplying the electric motor with extra juice until the demand decreases. Sure, it's not going to cover you in ALL cases, but it'll probably be able to help our the majority of the time.

Think to yourself for a moment, how many times do you floor your car in your daily drive, and how long are those durations? How often is the car able to sit in overdrive and cruise efficiently?

 

[Bignate603]

Originally posted by: 91TTZ

Originally posted by: Bignate603

So you'd have to let your car idle for a few minutes to charge up the capacitors before you left? Or would you just drive at 20 mph because your capacitors are out of juice because you accelerated hard and then coasted to a stop a few times between a series of stop lights? The engine would be too small to accelerate from a stop without the energy storage and capacitors have some serious drawbacks. .

No, the engine would still be big enough to drive the car on engine power alone. If a Prius's battery runs out, does it only go 20 mph? No. The car still has 76 HP. Not going to win any races, but you won't be holding up traffic, either. Hell, my first Toyota Corolla had less HP than that, and wasn't too much lighter.

What you described is a typical hybrid that uses capacitors instead of batteries. It will max out at the same limits as a typical hybrid with the possible disadvantage that capacitor charges dies down over time so you'd end up with less of an advantage from the energy storage. Tack on safety issues and you've got something that isn't really advantageous. It's not exactly a big design change and I can guarantee that any car company considering a hybrid had the same idea about capacitors instead of batteries. None have chosen to use them. I'm sure that's not just by chance.

 

[91TTZ]

Originally posted by: Bignate603

Originally posted by: 91TTZ

Originally posted by: Bignate603

So you'd have to let your car idle for a few minutes to charge up the capacitors before you left? Or would you just drive at 20 mph because your capacitors are out of juice because you accelerated hard and then coasted to a stop a few times between a series of stop lights? The engine would be too small to accelerate from a stop without the energy storage and capacitors have some serious drawbacks. .

No, the engine would still be big enough to drive the car on engine power alone. If a Prius's battery runs out, does it only go 20 mph? No. The car still has 76 HP. Not going to win any races, but you won't be holding up traffic, either. Hell, my first Toyota Corolla had less HP than that, and wasn't too much lighter.

What you described is a typical hybrid that uses capacitors instead of batteries. It will max out at the same limits as a typical hybrid with the possible disadvantage that capacitor charges dies down over time. It's not exactly a big design change and I can guarantee that any car company considering a hybrid had the same idea about capacitors instead of batteries.

Correct, that's what I've been getting at. You made it sound like a giant leap of technology to do it.

What I'm striving for isn't a performance improvement over today's hybrids, it's to achieve most of the performance of a hybrid at a much lower cost by eliminating the expensive battery.

Most car companies seem to be aiming for a pure electric car, but that comes at a high price. I'm aiming for a more widespread adoption at a much lower price. I'm not trying to eliminate the internal combustion engine, I'm trying to get the most efficiency out of it as possible.

 

[SickBeast]

Apparently the Volt will get around 60 mpg when run with the motor running as a generator. I find it interesting that this seems to be more efficient that running a straight gas motor. They say that every time energy changes state, there is loss. The Volt seems to prove that theory wrong in a sense.

 

[91TTZ]

Originally posted by: SickBeast
Apparently the Volt will get around 60 mpg when run with the motor running as a generator. I find it interesting that this seems to be more efficient that running a straight gas motor. They say that every time energy changes state, there is loss. The Volt seems to prove that theory wrong in a sense.

It's not proving that theory wrong. The same laws of physics apply. It's all about tradeoffs, such as "Will the benefits of better engine management outweigh the added loss from converting energy to different forms?"

I think the Volt will be a failure. People will be happy that GM is producing a hybrid instead of SUV's, but when it comes time for people to make a purchase I think that they'll balk at the $40k price tag.

 

[Fenixgoon]

Originally posted by: 91TTZ

Originally posted by: SickBeast
Apparently the Volt will get around 60 mpg when run with the motor running as a generator. I find it interesting that this seems to be more efficient that running a straight gas motor. They say that every time energy changes state, there is loss. The Volt seems to prove that theory wrong in a sense.

It's not proving that theory wrong. The same laws of physics apply. It's all about tradeoffs, such as "Will the benefits of better engine management outweigh the added loss from converting energy to different forms?"

I think the Volt will be a failure. People will be happy that GM is producing a hybrid instead of SUV's, but when it comes time for people to make a purchase I think that they'll balk at the $40k price tag.

tax incentives lower the cost, but yeah.. it's definitely an uphill battle.

 

[Bignate603]

Originally posted by: SickBeast
Apparently the Volt will get around 60 mpg when run with the motor running as a generator. I find it interesting that this seems to be more efficient that running a straight gas motor. They say that every time energy changes state, there is loss. The Volt seems to prove that theory wrong in a sense.

No, it's just that you don't understand the trade offs that go into a typical car engine. It has to be designed to work across a huge range of RPM and power. It means that it works ok across the whole range but doesn't work amazingly well at any of them. If you can disconnect the wheels from the engine you can design the engine to work extremely well at one single design point. Diesel electric locomotives have been doing that for decades and get amazing efficiency. It's not some crazy theory, its been proven for quite some time.

 

[LTC8K6]

I'll leave you to your imaginary system and I'll stick with my turbines.

Lighten up Francis!

Hmmm... Efficient small Honeywell turbine for power instead of ICE... Can run on lots of different fuels...

The Greer SC turbine blade facility is fascinating. I went there to start up some equipment Honeywell purchased from my company. We make heat treating furnaces.

Forgot all about turbines for my "green" Obama grant grabber.

Another prototype I can try when Obama returns my call.

 

[Bignate603]

Originally posted by: LTC8K6

I'll leave you to your imaginary system and I'll stick with my turbines.

Lighten up Francis!

Hmmm... Efficient small Honeywell turbine for power instead of ICE... Can run on lots of different fuels...

The Greer SC turbine blade facility is fascinating. I went there to start up some equipment Honeywell purchased from my company. We make heat treating furnaces.

Forgot all about turbines for my "green" Obama grant grabber.

Another prototype I can try when Obama returns my call.

I actually work for Honeywell, the guy I sit next to is working with Greer for new blade technology. Interesting stuff.

There's another guy on my floor that's dropping a 1500hp turbine into his power boat. Twice the power of the built up 454 he had in there at less than half the weight. I think it would awesome to get a little APU (there is one in the 90hp range) and put it into a go kart. That thing would FLY.

 

[SickBeast]

I'm wondering how much money it would save to remove the gas motor from the Volt and just leave it with the 40 mile range. For people just wanting a commuter car and trying to save money, if it would take enough off the price, I say it might be worth it.

Also, removing the motor would give it more pure electric range due to the reduced weight.

 

[Bignate603]

Originally posted by: SickBeast
I'm wondering how much money it would save to remove the gas motor from the Volt and just leave it with the 40 mile range. For people just wanting a commuter car and trying to save money, if it would take enough off the price, I say it might be worth it.

Also, removing the motor would give it more pure electric range due to the reduced weight.

I actually like the idea of giving people the option to choose if they want the gas engine though it would make the optional equipment list look funny...

Options:
Navigation
Sunroof
Leather
Engine

 

[LTC8K6]

You could probably add more batteries if you could remove the engine...

 

[Muadib]

Originally posted by: Bignate603

Originally posted by: heymrdj
I still have to say what about KW costs. No one seems to talk about what it costs you per year to charge these things to drive them for x amount of miles compared to the fuel for x amount of miles. Around here where the average electric bill to keep your home at 72 degrees in winter is 350$, a car charging you 300$ in electricity a month to drive won't feel much better.

Do the math. The volt has a 16kWh battery, but to increase battery life you only use half of it. So you need to charge up 8kWh per 40 miles. Let's say the charger isn't terribly efficient and it actually takes 9kWh. The average cost per kWh for the US is about $.11 per kWhr but let's say you live in a place where costs are higher, so its $.14 per kWh. That means it would cost you $1.26 for a full charge. That's 3.15 cents a mile. At $2 a gallon gas you'd need a car that gets 63.5 mpg for it to be cheaper. That's not impossible if you hypermile a prius but the actual mpg rating by Toyota is only 48/45mpg. Also, gas has typically been significantly more volatile than electricity in terms of cost. If gas hits $3 a gallon you'd need a car that gets 95.2 miles per gallon to be as cheap per mile. At $4 a gallon it would need to get 127 miles per gallon.

Has anyone seen an estimates of the mpg on the engine alone? I do 44 miles a day for my commute, and would like the whole picture. I absolutely hate the look of the Volt though. They should use the Cruze body instead.

 

[Mr.IncrediblyBored]

Originally posted by: Muadib
Has anyone seen an estimates of the mpg on the engine alone? I do 44 miles a day for my commute, and would like the whole picture. I absolutely hate the look of the Volt though. They should use the Cruze body instead.

About 50mpg running strictly on gas. http://gm-volt.com/chevy-volt-faqs/

Q: How many miles per gallon will the Chevy Volt get?
A: A bit of a trick question. For the first 40 miles it will get infinite mpg, because no gas will be burned. When the generator starts, the car will get an equivalent of 50 mpg thereafter. One can calculate the average mpg per for any length drive starting with a full battery: Total MPG = 50xM/(M-40)

 

[SickBeast]

I'm still floored by the fact that the Volt can get 50 mpg running a motor that is equivalent to a V6 w/ 250 horsepower. It defies logic. If this is the case, I'm shocked that GM did not release a car like this sooner seeing as they've had electric motor technology for 100+ years. I'm sure it's basically just using a juiced up alternator. It's not exactly cutting edge or rocket science.

 

[SickBeast]

I'm also curious as to what would happen if they removed the battery, or else removed the gas motor. Perhaps those would make interesting separate models for people with different needs for the car. Like I said, 50 mpg for a 250hp car is insane; I'm sure people would buy one on that basis alone, and if it was $5000 less because it didn't have a battery, it would be that much more popular.

 

[ElFenix]

Originally posted by: SickBeast
I'm still floored by the fact that the Volt can get 50 mpg running a motor that is equivalent to a V6 w/ 250 horsepower. It defies logic. If this is the case, I'm shocked that GM did not release a car like this sooner seeing as they've had electric motor technology for 100+ years. I'm sure it's basically just using a juiced up alternator. It's not exactly cutting edge or rocket science.

0-60 times, a bit over 8 seconds, are slower than midsized cars with 250 hp V6s (usually in the 6 second range), so their claim that it's like a 250 hp V6 isn't quite right. of course, a lot of that is weight, it may just match the 0-60 for an SUV or station wagon with that sort of engine.

Originally posted by: SickBeast
I'm also curious as to what would happen if they removed the battery, or else removed the gas motor. Perhaps those would make interesting separate models for people with different needs for the car. Like I said, 50 mpg for a 250hp car is insane; I'm sure people would buy one on that basis alone, and if it was $5000 less because it didn't have a battery, it would be that much more popular.

without the battery i doubt it will accelerate very quickly. all full throttle i'm guessing the car uses significantly more current than the engine can provide.

remember, at highway cruising speed horsepower is in the single digits or low teens for many regular cars. a small engine could easily provide enough current to allow the car to cruise and recharge the battery. and if properly optimized for a single RPM, do it with much less fuel consumption than a standard car.

 

[Bignate603]

Originally posted by: SickBeast
I'm also curious as to what would happen if they removed the battery, or else removed the gas motor. Perhaps those would make interesting separate models for people with different needs for the car. Like I said, 50 mpg for a 250hp car is insane; I'm sure people would buy one on that basis alone, and if it was $5000 less because it didn't have a battery, it would be that much more popular.

The reason you can get that high mileage after you drove the first 40 miles is because the engine only is running part of the time. The car runs constantly off the battery and the engine only turns on to charge the battery. It's basically an electric car with a highly efficient gas powered generator on board. The generator only runs for a short period to charge up the battery and then turns off. The big savings in fuel economy comes from the fact the generator can be optimized to be very efficient because it only has to run at one condition and because it's off the vast majority of the time. It will only kick on for a while, charge up the battery, and then turn back off.

You can't have this type of drive train without a battery, though they could do it with a smaller battery if they didn't want to have the ability to do 40 miles without any gas.

Without an engine it would just be a typical electric vehicle. That would be useful to some but not really revolutionary.

If this is the case, I'm shocked that GM did not release a car like this sooner seeing as they've had electric motor technology for 100+ years. I'm sure it's basically just using a juiced up alternator. It's not exactly cutting edge or rocket science.

The battery technology, engine optimization, and control systems are actually all relatively new technology. The biggest obstacle for them was the batteries. You can't compare the tesla battery packs to GM's because the Volt doesn't have an amazingly high price tag to let them buy expensive batteries. Even at $40k the volt had to find a high performance battery that was completely new so that it was able to be within budget. If it had been possible before now someone would have done it. There has been discussion for systems similar to this for years but the battery technology always was the limitation. You could do it but it would cost a small fortune in batteries (like the Tesla) and would require a long development process to get the control system between the electrical power and gas engine to work well. Control systems can be seriously difficult to design well.

 

[LTC8K6]

I'm still floored by the fact that the Volt can get 50 mpg running a motor that is equivalent to a V6 w/ 250 horsepower. It defies logic.

It can't, imo. Unless you never use that full equivalent power to accelerate.