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Hi,

Took a couple hundred mile trip today, Interstate and city streets and rural highway. On my 2013 I have a display that show kW and if it is coming from the battery, regen to the battery or from the engine/generator. Several times the display indicated power coming from the engine/generator and going to the battery. Even at 55-60 mph I would see the engine quit and just run off battery for several miles. I go the impression that the engine would run only at several preset RPM's and if the generator output was more than needed for driving some would go back into the battery. Sometimes the display would show a draw from the battery and the generator at the same time. I understand CS mode is suppose to run the engine/generator just enough to get you down the road without using expensive gasoline to charge the battery.

I would expect the system to have some excess if my speed/need for power changed significantly and often, but even on flat roads with no variance in speed (used cruise control), my power needs appeared to stay the same, but some of the engine/generator output went to the battery for some time and then the engine shutoff and used battery only.

Over a long distance it does not make a difference in gas consumption and I still arrived with an 'empty' battery.

I would suppose they can 'tune' the engine for optimum fuel efficiency and minimal vibration and sound if it is only used at certain RPMs. There were frequent times I could not tell the ICE was running other than looking at the power display.

Do you experience this on your 2013 or other years?

Thanks,

Tim.
 

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You are right.

The Volt's engine normally operates in ranges of peak efficiency AKA low specific fuel consumption. Look in the engineering threads, at least one thread has a map. Typically what you see is the ICE generating more power than the electric motor is using at a peak efficiency and then cutting off while the stored energy is used. Its pretty clever.

One exception is if you exhaust your battery and go to pure ICE power (reduced power mode.) Then the engine operates all over its fuel map. In this mode the battery is not used.

The other exception is if the battery is low and you put it in MM. The engine will howl trying to pull the battery up before you hit the hill. If the battery is exhausted before you get the top, you get to see the first exception.
 

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Yes and no. The engine output is adjusted to meet demands, in the most efficient way GM could find.

The Volt runs with a wide open throttle at all times, except during the 30 second warmup cycle (~50%) and momentary idling during transmission changes. The lowest speed the car ever runs the engine is ~1400 rpm.

Below 60-65, the car needs less power than the engine produces at WOT at 1400 rpm, so GM had to do something. Rather than throttle the engine, GM decided it was more efficient to cycle the engine - so the car runs the engine for a while at the most mechanically efficient point (virtual 6th gear, with 100% of the power moving the car delivered mechanically,) then tapers down to the 1400 rpm cutoff (usually spending some time on the way at the 1700 rpm beat efficiency point,) and then shuts the engine off for a mile or two.

If you go faster than this transition speed, the engine runs continuously at low RPMs in an eCVT arrangement.

I've never been there personally, but from my understanding, if you get into propulsion power reduced from an extended hill, the car will be running the engine at the peak 4800 rpm set point until you get back out off PPR. If you get into PPR because of a battery fault, then it attempts to match engine power to load requirements with no battery use.
 
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