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Originally Posted by lakedude
I cringe everytime someone uses the terms "series" or "parallel" hybrid and I don't much care for the terms "mild" and "full" hybrid either. None of the forementioned terms has any useful purpose. No one fully agrees as to what the terms mean so useing them is like using a random word that means next to nothing. The series and parallel terms are completely confusing and meaningless. The mild and full terms are used to describe IMA and HSD and imply that HSD is somehow better because it is "full". Pure hogwash.
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Well, it may be time to scrap the terms, but I think it is important, before we send them off to the grammatical graveyard, that we at least write them a proper eulogy and recognize where they came from.
I still like the report published in 2003 by the Union of Concerned Scientists.
http://www.ucsusa.org/assets/documen...2003_final.pdf
I don't believe that this report coined any of the terms, but it does do a fair job of defining them. The report is lengthy, and IMO repeats itself way too much, and it is dated and it uses existing technology (in 2003) to help define terms. But still does a decent job of defining them.
The only term, I believe, that has become murky to date is the term "full hybrid", since it defines its differentiating characteristic as "drive using only electric power". Honda's HCHII threw a wrench in the works by allowing the car to drive using only electric power, but with the ICE still turning. I don't think the writer of the report foresaw this development. As other developments occur, the terms will likely become more murky. But they are still somewhat important in that people need definitions in order to discuss (or argue) the finer points.
So, from the report:
See Table ES-1 and the supporting verbiage around it. This table differentiates:
Conventional Vehicle, Muscle Hybrid, Mild Hybrid, Full Hybrid, Plug-in Hybrid.
Figures 4-8 define:
Series Hybrid, Parallel Hybrid, Split-Parallel Hybrid, Toyota Series - Parallel Hybrid, and Basic Series-Parallel Hybrid drivetrains.
Note that it defines the HCH I and the Insight as a parallel hybrid (the HCH II didn't exist when it was written). This may be surprising to some, because I believe there is a popular misconception that since the engine, motor and transmission are all linked together in a line, or "series" in the HCH, that it is a series hybrid. However, a series hybrid is defined asa vehicle where "an electric motor is the only means of driving the wheels. The motor obtains electricity either from a battery pack or from a generator powered by an engine in much the same was as a portable generator." So, in other words, an EV with an ICE onboard who's only purpose is to recharge the batteries.
The report defines the Prius (and I would inject the FEH) as a type of series/parallel drivetrain, indicating that "The Toyota Prius made popular a new concept that combines many of the advantages of the parallel drivetrain with the series drivetrain's ability to maintain engine operation near its most efficient operating point."
My point in this diatribe is that the terms DO mean something, and they DO serve a purpose. But as the technology develops, the terminology will blur and new terms will need to be developed to replace many of these, or at least enhance them.