Quote:
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.
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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.