Topic: Volt = first 100mpg car

[Leviathan]

Why do people keep bringing this up?  No, the Volt is not for everyone.  If you commute more than 40 miles per day, you should probably look elsewhere.  But no one car is perfect for everyone, and the the Volt is no exception.  Like the Smart car, the Volt will be great around town but not as strong as a commuter (although likely better than the Smart!).  As others have said, a smart family might have a Volt and a traditional gas car for roadtrips...  nothing wrong with that.

Dunno. Everything I've been reading about the Volt points to it being a fine replacement for "normal" cars in every way whether you're a short tripper or long tripper or Jack Tripper. 50mpUSg when on generator? Sounds pretty good to me.

[tpl]

BUT.  If the gas engine can spin the generator against a 150 horsepower "load" of the electric motor then it must be capable of producing 150 bhp which is definitely isn't.  That 150 bhp has to come from somewhere.

Do you drive your Fit using 100% throttle 100% of the time? Of course not, and you won't drive the Volt that way either so you don't need 150hp all the time. Apparently GM will tune the gas generator to several fixed RPMs and will choose according to the load requirement.

So If by some magic the battery is flat you wont be going anywhere until the gas engine has rattled away for some time to get some charge into the battery.

Apparently the Volt runs directly off the generator with any excess power generated going to the battery.

So the car will not run properly unless they battery is 30% charged or thereabouts which to me would make it a bit problematical for driving across the rockies with a full load.

30% charge is a soft "limit" and still represents 24miles of range. Your rockies trip will include up AND down grades and you'll get some of your energy back through regen braking.

The next question that come to mind is: Can the car self start by which I mean, if the battery is completely flat is there are way with no external power source except maybe a tow trucks battery, of getting going again. Can the gas engine be started from a regular 12V source? Can the gas engine charge the main battery from dead flat.?

If not then I don't want one.

Dunno that, we'll find out in 2 years I guess. Lutz joked on the Colbert Report that you could charge the Volt from the 110v outlet of a Hummer so there *IS* an option    But it doesn't sound like the Volt is for you anyway.

The volt is not for me.  But I do indeed like the idea... if one wants a car that car run on electricity for a reasonable time in between charges then the Volt is the way to do it ( leaving out quibbles about gas or diesel, current batteries or unobtanium batteries)   It is still going to be a far more complex vehicle than just using a diesel of appropriate size.

No I realize that you don't need all the power for the generator all the time but the gas engine has to be capable of meeting high power demands for a short time I think. Which suggests that it has to be a reasonable size.... I think I saw it is  a bit over 1 litre so that should be plenty.

I do think the zero battery start capability is a necessity with NA weather

[G35X]

Total MPG = 50xM/(M-40) – Leviathan
That 50mpg was given in the early specs of the Volt with 1000cc turbocharged I-3 ICE.  The production model will have a 1400cc NA 1-4 ICE and GM has not made estimated mileage public yet.

From GM's official press release here
"The Volt's electric drive unit delivers the equivalent of 150 horsepower, 273 lb-ft. (370 Nm) of instant torque" – Leviathan

150HP is about 113KW, which the ICE/generator cannot supply alone.  You need additional juice from the battery pack. But, when the batteries are drained, where do you get the additional energy?  Anyway, that 150HP is available for only a short burst.  Try going up the Coquihalla highway from Hope to Merrit with depleted batteries.  Even if the necessary energy is available for more than a burst, the motor won’t be able to withstand the heat.  Suppose the efficiency of the motor is 95% (real number should be closer to 90%), 5% of 113KW, or about 5.6KW, turns into heat, which is something like turning on four coil elements of kitchen stove at the same time, all at the max setting. Where does this heat go?  Before long the motor will fry itself. Unlike ICE, heat of which is transferred to liquid coolant directly from the metal walls, electric motor’s coil windings have insulation, which is not a good heat conductor. Because of this the first generation Prius had motor failures.  The duty time of the rear wheel driving motors on the Toyota Highlander Hybrid and Lexus RX400h is limited to avoid the heat damage.  The amount of current of 113KW from a 300V source is about 218 amps if the motor is 3-phase. The wire should be as thick as the one that goes to the starter motor of an ordinary car.

[Leviathan]

Well, I dare say that the GM engineers are way ahead of either of us. We'll see how the car behaves in everyone's favorite "what if" scenario two years from now. Until then all this hand wringing is just that, hand wringing.

[EV Dan]

@G35X

There are 100s of thousands of electric locomotives around the world, including those without any diesel backup whatsoever. All the time they have to accelerate and go up the mountains and yet they seem to perform flawlessly.
If someone decides to burn a Volt by going full "throttle" up hill with AC set to subzero I think it may actually burn, or likely the electronics will limit the input once the motor reaches critical temp.
But then again an ICE can be overheated under extreme driving conditions as well.

the other part of the question has been answered; there is no need for a constant 150hp. For acceleration the batteries can supply enough current to the motor to crank out that power. Any way you look at Volt you gotta admit GM managed to pull it off this time. By the time all the greenest of us get one, production volume of battery plant should be sufficient to bring the price down.
I have no clue why GM here gets beaten more than Chrysler and Ford put together. In my experience their cars have been very reliable. 

[G35X]

“ …I dare say that the GM engineers are way ahead of either of us… “ – Leviathan

Maybe so, but you cannot cheat the laws of physics. I think GM marketing people are way ahead of engineers, who must be under heavy pressure now.  Conceptually the ICE>generator>motor serial drive is not new and much simpler than the parallel design. The most difficult part of the serial design must be charge/discharge power management and heat management firmware.  I think Toyota was wise to choose the parallel design with part time "small" electric motor even though its controlling algorithm is very complex.  The question today is not whether you use zero gas or not, rather it is how much we can reduce the gas consumption.  By driving hybrids and other fuel-efficient automobiles if we can reduce the gas consumption by 20% nationwide, which is possible even today, that’s a tremendous accomplishment. My next car will be a hybrid.

[G35X]

“ …There are 100s of thousands of electric locomotives around the world… “ – Dan Yanoff

Yes, indeed.  They are operating at much higher voltage than Volt’s 300 volts. Besides, their motors have the luxury of being heavier and more robust. Suppose the voltage supplied is 1500 volts, or five times of 300 volts, with the same amount of current (read: heat) you can get five times more power.  The Volt is said to have a 45kW (continuous) electric motor. With the same amount of current you can obtain 225kW of power per motor for trains.  Actually, older design “shinkansen” train motor is rated at 210kW each, 24 of which are used per train. 

“ …there is no need for a constant 150hp… “ – Dan Yanoff

Yes, that’s true.  But, going uphill requires a lot of energy (mass*acceleration of gravity*height).  For example, if you want to drive a car weighing 1800kg up from the sea level to 1000 meter elevation in one hour (something like to go from Hope to Merrit) you need 49kW of power in addition to the power required for going on a flat highway (against wind and rolling resistance), which should be about 15 to 20kW.  The combined power of 64kW to 69kW is more than the continuous rating of Volt’s motor. Therefore, you have to slow down, taking maybe 100 minutes to cover the same distance.  In other words, the Volt, with its 53HP motor, is a rather anaemic automobile.

I am not saying this is bad. If everybody is happy with sub-100HP automobiles, electric or otherwise, we can reduce fuel consumption siginificantly.

[Sir Osis of Liver]

Industrial 150hp motors typically have efficiency rating of 95% so I wouldn't expect this to be any different.

Winding temperatures are typically monitored by RTD or thermocouples, and in motors this size would typically have an alarm point around 160C, with shut off around 185C. The windings for a motor would not hit that temperature at its rated service factor at ambient temperatures less than 40C. Given the cooling air provided, and any other measures they've taken ie heat sinks, I don't see a problem here.

We've run motors as large as 800hp on 600v using soft starts on very high inertial loads (squirrel cage fans) with no problem other than long start times, so using 300V for 150hp motor shouldn't be a concern.

Having said that, we don't know any details on the motor. The 150hp rating could be peak, which is essentially what G35x is saying, and a fairly meaningless number in the real world. I've never heard any numbers indicating the continuous rating of the motor, that's the important one. So it's all pretty speculative at this point.

[The Mighty Duck]

The locomotive is also moving far, far, more mass.  I'll wager if you looked at power/tonne, even with a locomotive with no train, the Volt would actually come out ahead.  Couple a hundred cars to the locomotive and it's game over.

[Ex-airbalancer]

800hp on 600v using soft starts on very high inertial loads (squirrel cage fans)
That a big f*ucking fan
I do not think my clamp on meter would fit around the wires, nevermind I do not think my meter could measure that high of an amperage

[EV Dan]

The bigger question is why a squirrel needs such a fan 

[G35X]

“ …The 150hp rating could be peak… “ – Big_Thumb

In spite of all the hoopla GM has not announced detailed specs of the Volt yet. In the following site you will find the motor used for prototype is rated at 45kW continuous:

http://www.chevy-volt.net/chevrolet-volt-specs.htm

Imagine supplying 113kW of power to a 45kW motor. Before long it will fry itself or be cut off.

Thank you, Big_Thumb, for the information on industrial heavy duty motors. With heavy gage coil windings their internal resistance can be very low.  Whether this kind of motor can be pushed into an automobile or not, I do not know.  The Volt has to squeeze a 1400cc I-4 ICE, a 53kW generator, a 16kWh battery pack and a 45kW motor into its mid-size body.

Heat generated by electrical current through a resistive load is very high. You cook with it.  The KitchinAid mixer gets very hot if you knead sticky dough for 10 minutes or so.  The Pentium MPU can become so hot that the heat melts solder joints if not properly ventilated.

[Sir Osis of Liver]

45kW is about 60hp.

A higher revving motor would be physically smaller, so say a 3560rpm motor. That would give a braking torque of 88.5 ft/lbs (at 3560rpm) which isn't bad for pushing a car along at speed. Starting torque is at least 150% of braking torque, so 132ft-lbs, but you can get more, up to 275% depending on motor type and power electronics so 245ft-lbs.

The 2.4L in a Camry runs about 160ft-lbs for comparison.

Again all speculation, cause we don't know what they've spec'd.

[Sir Osis of Liver]

800hp on 600v using soft starts on very high inertial loads (squirrel cage fans)
That a big f*ucking fan
I do not think my clamp on meter would fit around the wires, never I do not think my meter could measure that high of an amperage

Biggest fan motors the company has worked with lately were 3000hp fans at Nanticoke generating station. I can't remember is they were 4160v or 12.7kV.

[safristi]

Quit FANNYING about and let the WIND  generators in yer hair...... .....

[Leviathan]

This article explains how the battery charging will work. In the comments was this link to Tesla's site about disposal of their Li batteries.

[G35X]

The article states “ …The generator does not fully recharge the battery. It doesn’t make any sense to, for then you would be using petroleum to travel. The goal is to use the electric grid, so the car will carry on at approximately that 30% state of charge until the driver can get to an outlet and then fully recharge. Without recharging at an outlet, the car could drive indefinitely using gas and refills, but doing so would defeat the whole point of petroleum displacement... ” .  As publicity stunt saying “petroleum displacement” is good.  But, this from a company selling millions of gas guzzling trucks, SUV’s and 8-cylinder passenger cars?  The token number of Volts won’t make any difference.  As I mentioned earlier in the forum, the question is not “gas or no gas”, rather it is reduction of gas consumption overall.  If the Volt-like drive system is more efficient than conventional ICE>transmission system, then go ahead and make the ICE>generator>motor system with much smaller buffer battery (cheaper and lighter) as the mainstream drivetrain for the fleet.

The benefit of plug-in automobiles such as the Volt is they utilize otherwise wasted off-peak electric energy.  If we charge them during peak hours (while we are at work, for example) it only adds burden on the grid.

If the purpose of the ICE is only to maintain state of charge at around 30%, then it would be much cheaper to drive purely electric automobile such as Mitsu iMiEV with a small Honda gas generator in the trunk for just in case.  If unfortunately you ran out of juice, just stop at roadside and plug it in to the Honda for about one hour, which should give you another 10 mile or so of drive.

[Triple Bob]

Isn't the purpose of this car for people who have a say 10 mile commute and then go further at weekends?  I would quite happily use a car like this to drive to work and back solely on electricity, and then use gas for longer journeys at the weekends.

If used in this way by a large number of people with the same type of journey as mine you would save a fortune on gas?  I bet that the total distance powered only by electricity (is it 40 miles?) would cover a large proportion of the nation's daily commutes...

Isn't THAT the point of this car?

[EV Dan]

"If the Volt-like drive system is more efficient than conventional ICE>transmission system, then go ahead and make the ICE>generator>motor system with much smaller buffer battery (cheaper and lighter) as the mainstream drivetrain for the fleet."

If they (GM) did that they'd have to call it a Prius and I suppose why the latter wasnt made a sequential hybrid in the first place (much simpler design) is because they would have to use a bigger more powerful motor to pull the car, which would fry a small battery (higher motor power - lower internal resistance).
IMO GM has struck gold with Volt

[Sir Osis of Liver]

We all get it, you hate domestics, move along.

For what it is, I believe it to be very well thought out and moves the technology forward.  Diesels are another kettle of fish altogether. There is a lot of evidence that Americans are more receptive to hybrids than diesel, so that's how GM is leaning, just like Toyota, Nissan, Ford, Chrysler and Honda. They all are looking at specific diesel applications, but none of them are racing to widespread adoption.