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Confused about PHEV, Hybrids, etc...

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YurkshireLad:
Hybrids are better around town than they are on the highway. If you're doing mostly highway driving, I don't think a hybrid is the best option. It's not bad, but I don't think you'll get the best mileage out of it. You're not doing enough braking to put energy back into the battery. I think I got my best economy on a single journey while driving up and down the hills in Vermont. I think it was something like 4.6l/100kms.

nctnico:
That depends on the type of hybrid; the only hybrids to consider need to have a true Atkinson cycle engine. Such engines are much more efficient so even on highways, you'll get a much better mileage compared to a conventional ICE based car. Unfortunately there are only a few manufacturers that make such hybrids (typically with a drive train from Toyota).

Cerebus:
Just for completeness, there's one category missing, the mild hybrid.

These have thrown away the alternator and starter motor, and replaced them with a motor capable of moving the vehicle and being used as a generator. This is combined with a relatively small lithium chemistry battery - 1 kWh or less. So to start moving you use the electric motor, then the ICE is "bump started" once you're moving. They will have a small, low speed all electric range, but we're talking 10s, perhaps 100s of metres, not kilometres. Typically there's a small amount of regenerative braking as well, and the motor is obviously used in generator mode to recharge the battery. At the end of the day it's more of a re-working of the standard ICE engine's ancillaries than a true hybrid.

ejeffrey:

--- Quote from: nctnico on July 26, 2022, 07:31:12 pm ---That depends on the type of hybrid; the only hybrids to consider need to have a true Atkinson cycle engine. Such engines are much more efficient so even on highways, you'll get a much better mileage compared to a conventional ICE based car. Unfortunately there are only a few manufacturers that make such hybrids (typically with a drive train from Toyota).

--- End quote ---

This.  The biggest efficiency improvement on traditional hybrids comes from using a more efficient engine and keeping it running in the most efficient operating range as much as possible.  The battery and electric motor work to provide a torque boost to get more acceptable performance out of an Atkinson cycle engine and also to average out load a bit so that the engine can stay operating at peak efficiency more of the time.  Regenerative braking definitely helps around town, but the car will also charge the battery from the engine while cruising if doing so keeps the overall system operating higher efficiency.

As for mild hybrids: they are more like an improved stop-start system with a 48 volt electrical system so they can use an electric AC compressor.  They hardly count as a hybrid -- while the motor can technically move the car it is a negligible fraction of overall traction power.

Someone:

--- Quote from: Cerebus on July 26, 2022, 11:22:07 pm ---Just for completeness, there's one category missing, the mild hybrid.

These have thrown away the alternator and starter motor, and replaced them with a motor capable of moving the vehicle and being used as a generator. This is combined with a relatively small lithium chemistry battery - 1 kWh or less.
--- End quote ---

--- Quote from: ejeffrey on July 26, 2022, 11:41:20 pm ---As for mild hybrids: they are more like an improved stop-start system with a 48 volt electrical system so they can use an electric AC compressor.  They hardly count as a hybrid -- while the motor can technically move the car it is a negligible fraction of overall traction power.
--- End quote ---
They might be stretching the term "hybrid" but a battery of roughly 1kWh is close to the optimum overall energy efficiency for interurban driving (not carting around more weight than required, it is unusual to have conditions where a car can use more than that from regenerative braking.

Around town with lots of start stop and low speeds, pure electric makes sense.

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