Volt may become a parallel hybrid

[RobertSmalls]

Originally Posted by dcb

I think it is very telling though.

According to that article, the 71hp hp gas motor is struggling to keep the car going 50mph

the 149 hp electric motor on batteries can go at least 100mph

it should take no more than 1/4 of 149 hp to go 50mph

so of the 71hp in the gas motor, no more than 37 hp make it to the wheels via the "electronic transmission"

the transmission of power in this series configuration is %52 efficient at best.

It certainly doesn't add up, if this is the case, how did they ever figure on 50mpg in range extended mode? Something isn't right here.

DCB, those numbers are too speculative for any sort of conclusions. We only know peak HP, not the full torque curves. Plus, the performance problem described was a lack of passing power at high speeds under electric power alone. That's very hard to put numbers to.

52%? Probably not. Based on the performance of the Honda Accord Hybrid, I'd expect around 75-85% efficiency in a series hybrid's "electric transmission". This number is not disastrous like I expected it would be, but it's surely worse than the losses from having to run your gas engine as much as 10% away from your RPM target (achievable from 40-90mph with four gear ratios). I take it from the "power generation losses" mentioned in the article that GM engineers are inclined to agree, much to the chagrin of GM's marketing department.

Additionally, a series hybrid requires more and larger electric motors to achieve the same peak horsepower, adding substantial weight and cost.

Here's an article where a GM spokesman (PR guy) confirms that switching to a parallel hybrid arrangement is "a matter of software": Exclusive: Chevy Volt Is More Hybrid Than Previously Thought | Hybrid Cars



Well, good. Now I want an EV mode toggle switch so I can make sure my EV mode operation coincides with the low-speed, heavy traffic portions of my commute. I also want to see a version with a 6kWh battery pack for around $23000. Call it the Cruze PHEV-12, because I am so disgusted with all the marketing and over three years of hype surrounding the Volt name.

[jamesqf]

Originally Posted by dcb

According to that article, the 71hp hp gas motor is struggling to keep the car going 50mph...

Doesn't quite make sense. It takes about 17 hp to keep the Insight moving at ~60 mph (tested by engine-off coasting down a long mountain road), and the Volt's weight/drag surely isn't 7 times the Insight's.

[cfg83]

RobertSmalls -

Originally Posted by RobertSmalls

DCB, those numbers are too speculative for any sort of conclusions. We only know peak HP, not the full torque curves. Plus, the performance problem described was a lack of passing power at high speeds under electric power alone. That's very hard to put numbers to.

....

That's what I was thinking, aka the "Autobahn Issue".

Question: How difficult would it be to have more torquey electric motor? I am guessing that this is harder because the rest of the system has to be resized. It's probably cheaper/easier to beef up the "direct mechanical link between the engine and wheels" you quoted at the start of the thread.

CarloSW2

[MadisonMPG]

Would GM just drop this, I'm tired of hearing about it.

[NeilBlanchard]

Repeat after us: The Chevrolet Volt's gas engine does not drive the wheels! — Autoblog Green

[Patrick]

Originally Posted by NeilBlanchard

Repeat after us: The Chevrolet Volt's gas engine does not drive the wheels! — Autoblog Green

Oh, yeah?

"Efficiency is the Volt’s mantra,” Peterson said. “We will take whatever method we have to get there.” Asked if Volt engineers would use the gas engine to power the wheels—a signature of a parallel hybrid system—if it meant greater efficiency, Peterson replied, “You could do it. Absolutely. It’s a matter of software.” He added, “You have some motors, a planetary gear box, there’s a variety of things we can do in there.”

Sounds like their PR guy needs a PR guy.

[Frank Lee]

GM might be trying to throw everyone off kilter. They did that before with the Corvair program- called it a Holden- to keep the secrecy intact.

Or it could be that the marketing dept. was out there blabbing and hyping without the true facts. Wouldn't be the first time that's happened.

[NeilBlanchard]

Combustion Engine Does Not and Will Not Turn the Volt’s Driveshaft Ever. Got it?

[dcb]

They still have not accounted for the transmission losses. Looks like folks are guessing it is from %75 to %86 efficient. The BSFC argument has been analyzed also and does not conclusively make up for those losses, especially on the hiway.

But not calling it a hybrid is also deceitful, the prius can also move on electric power only too. Plus all the other deceitful stuff (i.e. 230 mpg)

I would have been a happy US consumer with an electric car, not a hybrid. Electric is simple, could have been to market long ago with more room for batteries for less cost and development/certification time. Don't know why they didn't release an electric only car and sort out the fartbox as an option later. Opportunity lost.

Signed,
very disappointed in the states.

[basslover911]

Originally Posted by MadisonMPG

Would GM just drop this, I'm tired of hearing about it.

Seriously guys... lets make a law to never talk about that car again here... I bet it just gives GM an excuse to keep on lying to everyone.

Next thing is their going to make it nuclear power... never needed fillup! OR go a completely different dirrection and make it a motorcycle! or a minivan!