Quote:
Originally Posted by tumnasgt
I suspect that having direct drive instead of the transmission would more than make up for the loss. Fixed output generators are much more efficient than variable output as they run at the most efficient speed. An hybrid car is a perfect application for it as the alternator can be set up to load the system at its most efficient level. As I understand it, the Volt only provides the amount of electricity needed to power the wheels + a bit extra in case of steep hills, so it cannot always be running the gasoline engine at peak efficiency.
Regardless of which is actually better, I agree that GM made the wrong decision. Of the two sensible solutions (true series hybrid or Prius-like hybrid), they managed to combine the worst bits (having a transmission and going gasoline -> rotation -> electric -> rotation).
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Do you have any sources? Direct drive instead of a transmission only frees up ~5-10% depending on the transmission, and some hybrids are practically direct drive anyway IIRC (Toyota and licensing their patents). Maybe for small engines fixed output generators are significantly more efficient, but for hybrid automotive engines efficiency doesn't
vary a lot, especially over the speeds/loads the engine is operating most of the time. The drop in efficiency from converting everything to electricity and then back to mechanical power via a motor is way more than any gain from running an engine at whatever discrete states. The proof is in the pudding really. The Volt should at least do better in the city than the heavier/larger fusion hybrid, but it does significantly worse because it is a series hybrid.