ABG: Chevy Volt completes 1776-mile Freedom Drive in just 3 days; EVs can't match that

The Prius could do that too, being a series/parallel hybrid. Why doesn't it?

Because, actually, running the ICE at peak efficiency would be annoying.

Petrol engines do have one, peak, most efficient point. It's usually at about 40% of the rev range. On the Gen 2 Prius it's at around 2,700rpm and on Gen 3, about 2,100rpm. (This is the centre of the lowest contour on the Brake Specific Fuel Consumption map - Toyota have chosen not to go lower than 230g/kWh on the Gen 2 map and 220g/kWh on the Gen 3, probably that there wasn't a large enough region to show at 225 or 210.)

It would seriously alarm most drivers if the engine suddenly revved, from off, to this speed when travelling at only 20-30mph, where most cars are running at 1,000-1,500rpm. It would also wreck the supposedly all-important Noise, Vibration and Harshness metrics.

So to avoid alarming drivers, Toyota have chosen to only vary engine speed up a little. If cruising at 20-30mph, the engine speed actually doesn't change from its minimum, it increases load; increased load is (up to a point) much more efficient than low-load, so the extra load to recharge is practically free. I would expect GM to have made the same choice.

You may be surprised at how little power is actually necessary to cruise on highways: about 20kW at 70mph. On the Gen 3 Prius this falls at about 2,000rpm - actually slower than the peak efficiency.

 

I don't have a very good test environment. I did two attempts and they came out to 6.7 seconds and 7.6 seconds. There are hills so I could not do a flat test and traffic set the conditions of where I felt comfortable doing a run. Outside temp 88, AC set at 77. First attempt the battery was full, on the second it was down a little less than half power. For the test I had a warmed up engine, and kept the speed at 62 for about 30 seconds then accelerated.

This is mainly as another data point for the volt. For ultimate low energy consumption it doesn't matter, stay behind the slower car. But some of us don't want to give up ability to quickly pass on a two lane highway. Most of the time the car that I want to pass is going 50 or under, but I want to minimize the time I spend in the lane of oncoming traffic.

 

Yes it does. The Volt will maintain a minimum charge level on the battery. The Volt uses 8 kWh out of 16 kWh battery capacity. Let's say it uses the middle of the range so it has 4 kWh on the bottom and 4 kWh on the top that it doesn't use.

That means if you are in charge sustaining mode, it will aim to keep the battery at 4 kWh. Floor it to pass someone and charge drops below 4 kWh? The gas engine will run until the battery is charged back up to 4 kWh so you have that bit of reserve when you floor it again.

In CS mode the Volt will drive just like it does in EV mode - the only difference being if you exceed the power capability of the engine for an extended period of time - such as climbing a very large mountain at high speeds and you deplete the battery to a point where it reduces power output to keep the battery charge from going any lower - you know, just like the Prius does and many have experienced that as well.

 

You are absolutely right, there are other considerations. My only point was that the generator in a series hybrid can be much smaller than peak horsepower needs.

On your point about noise and the prius, the engine seems to rev and slow down in a counter intuitive fashion. So at least for me, the hsd does not do a good job at creating a good engine note. It does provide a highly efficient transmission which is more important in the prius. GM did indeed change their design plan, and made the ice rev more like a driver would expect it to rev. So your conjecture has been confirmed.

 

I hope you are right. But the above runs counter to everything I've read about the Volt. Of course, with GM telling us nothing but bunnyfeathers about 230 mpg and 1776 miles on a trip, we probably won't really know how the car functions until they actually start selling it to the public (assuming they ever do) and we get test results from independent sources.

 

Thus sacrificing efficiency for appearance and burning more gasoline overall. How like GM!

 

Go and read every post for the last two years on gm-volt.com , i have. Drees has it right. on hitting 25% SOC ICE starts up, and will maintain 25%. i believe you can drop to either 20% or 15% before power output would be reduced. using the 5% window you have 800watt hours, enough to drive 4 miles at 60mph or so. the genset can output 53kw, which is enough to maintain speed of 100mph and supply a couple of kilowatts of accessory load. if you find a mountain you wish to climb at 100mph, then obviously you'll need more than 53kw, and you'll draw whatever was left in the pack down to 25%, then the 5% window, then your power goes down to 53kw and your car begins to lose speed. just like the prius, and really, like most cars. you do have the option however to use "mountain mode" which will put an (currently unspecified) additional level of charge into the pack. while there's power in the pack you can charge up that mountain with 110kw of power.

I am eagerly waiting for an Ampera, i only got the prius as a stop gap and hate burning petrol, both for the political and financial ($7 a gallon in good ol blighty) reasons, but also don't want to own two cars. work is a 34 mile round trip, our weather is consistently mild and i have a driveway. the Ampera will suit me (and millions of other europeans) perfectly. i don't care if it's £25,000 (i like the way you keep quoting $40,000 - the price has still not been announced) and CS mode is "only" 40mpgUS because here in $7 land the car PAYS FOR ITSELF in 10 years.

Of course, if your life is suited to a BEV then more power ( ) to you. it wouldn't work for me, i need to know i can always get in my car and drive as far as i need to. i'm happy to support cars going in the right direction (the prius included) and will be happy once i can get an EV with 300+ miles of range for a reasonable price. in the interim i'll make the tradeoff of burning -some- petrol, and hope gen2 of the Ampera has more EV range for the same money, or that the Prius PHEV2 has true (>62mph) EV mode and more range.

 

10 years compare to which car? Prius?

 

That's still very good. Volt does it in 10 seconds.

 

Is that while it's depleted batteries are trying to be recharged? ... or on a fresh pack. So many variables ... such a high price ... such an unreliable company. They STILL want to sell you an internal combustian engine, at all costs.

Why would I want a GM ICE. If I have an EV ... and absolutely positively HAD to go farther than 100 miles w/out recharging ... I could make up one of these puppies to tow behind my ride:



THAT way, I'd be more comfortable, knowing I didn't have to rely on a GM ICE.



.

 

Read this somewhere.

Drive in your Leaf till battery depletion. Then switch to the Prius you have been pulling along, with Leaf hitched to the back. Repeat after every recharge

 

That picture is just SO WRONG!!! The EV that put all gas cars to shame, towing a gas engine. :mmph:

 

My concept of the Volt is an EV with an onboard gasoline engine that drives a generator to charge the batteries. Because it is a plug-in the arrangement will give fantastic mpg on short trips around town. But on a long high-speed trip I wonder if the gasoline engine/generator can keep the batteries charged at a level that will sustain the speed and the effiect on the mpg. From the statements that GM has made it sounds like the car becomes essentially a normal gasoline engine driven car under those conditions.

 

Now now, Daniel . . . you know, you COULD just as easily have that trailer generator running on LPG or CNG ... and then? It really isn't too shabby an idea!

.

 

You COULD run any conventional car on LPG or CNG.

 

can't we just put lance armstrong on a trailer on a bike and have the pedal power charge the car. I know it would work. I saw this documentary called gilligan's island and they used a bike to make electricity.

 

Didn't they also make a radio out of a coconut?

 

The smell of freedom is apparently the smell of the gasoline that's burned to drive long distances to make some sort of obtuse point.

 

Indeed. In fact GM has also promised us 1 million fuel cell cars on the road by.... wait for it.... 2010. But that was promised almost 10 years ago. The new goal is... wait for it... ten years from now.

:focus:...

 

TEN YEARS??? That's ten percent of the time the human race has left to live! I don't think I want to wait that long.