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Discussion Starter #1
...clean sheet, ground up, dedicated EV production facility - will look nothing like this:






(hey Infinity, EAMES wants their LOUNGE CHAIRS Back)

And be manufactured in China, likely for the China market.

After reading this line regarding Infinity's plans:
...multi-motor all-electric system, as well as a range-extending system pairing an electric motor with a small four-cylinder gas engine up front, and one or two [Electric] engines in the rear, ... The gas engine would serve as a generator to power the motors or help recharge a drained battery.
I can't find a lot of info, and I'm piecing tidbits together. My question is regarding Series Hybrid Propulsion. The Q-EV sounds like its based on the Nissan Note e-Power technology. Basically a full-time “range extender”. A little 1.2L engine coupled with a Very little 2kWh battery, The Nissan Note e-Power gets 88 MPG & sold about 100,000 units in its first year in Japan.

The Q seems to aim for much bigger expansion. A 400HP motor and perhaps a 20kWh battery for a luxury sedan that may get 120 MPG, with "Ludicrous-like" Instant torque acceleration of sub 4 second 0-60...near silent operation, and ZERO range anxiety.

Is this a viable possibility? Should this type of Hybrid Propulsion system even be considered an EV (the car has no plug port)? Is a 5X reduction (not elimination) in CO2 for a vehicle of this class be a win-win/best of both worlds?
 

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No plug would be a mistake, as adding grid charging ability should be a relatively minor cost for the luxury vehicle. My Prius battery only has a 3 kWh usable capacity, but it still plugs in (24k EV miles so far at 30% EV use). A serial hybrid certainly makes sense for those who want a very fast car, good fuel economy, and convenience of standard refueling. In this way, a relatively weak (small / efficient) ICE engine can be installed to run at peak efficiency to resupply the battery, which is capable of feeding tremendous power to the electric motors for quick acceleration. This is probably how most sports cars should be designed as it doesn't make sense to lug around a big 600 HP engine when it almost never outputs that amount of power.
 

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Is this a viable possibility? Should this type of Hybrid Propulsion system even be considered an EV (the car has no plug port)? Is a 5X reduction (not elimination) in CO2 for a vehicle of this class be a win-win/best of both worlds?
It's basically a conventional hybrid like the classic Prius in terms of its capability. Nothing really wrong with that - the Prius gets incredible gas mileage. But it's not something I'd call an EV in any sense. That's why I sold my Prius C and bought a Bolt.
 

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Discussion Starter #4
It's basically a conventional hybrid like the classic Prius in terms of its capability. Nothing really wrong with that - the Prius gets incredible gas mileage. But it's not something I'd call an EV in any sense. That's why I sold my Prius C and bought a Bolt.
The Toyota Prius is somewhat unique among hybrids. It's a combination of both of the previous types and is known as a series-parallel hybrid. This is possible because of the Prius' power split device, a special gearbox that connects the gasoline engine, electric motor and generator together into one unit.
It seems that the Infinity Q e-power would be 100% series hybrid. Where the engine is the generator and not connected to the drive/propulsion system to move the wheels. Since it would have an Electric motor, and an Electric battery, isn't there more "E" than "V"? So to speak.

A serial hybrid certainly makes sense in for those who want a very fast car, good fuel economy, and convenience of standard refueling. In this way, a relatively weak ICE engine can be installed to run at peak efficiency to resupply the battery, which is capable of feeding tremendous power to the electric motors for quick acceleration.
To better restate my question;
Is an ICE engine acting as the main altenator for an Electric traction motor vehicle more efficient than a ICE engine simply powering the vehicle directly? I know all diesel-electric locomotives use this system, but that's an entirely different mission where low voltage/high current gets the very heavy train going, and higher voltage/lower current maintains an efficient constant speed (plus there is no transmission). If the diesel-electric locomotive model that's been around for over 5 decades (series hybrid like the Infinity e-power) is more efficient and versatile for all terrestrial transport, why is it just now being introduced into cars?
 

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To better restate my question;
Is an ICE engine acting as the main altenator for an Electric traction motor vehicle more efficient than a ICE engine simply powering the vehicle directly? I know all diesel-electric locomotives use this system, but that's an entirely different mission where low voltage/high current gets the very heavy train going, and higher voltage/lower current maintains an efficient constant speed (plus there is no transmission). If the diesel-electric locomotive model that's been around for over 5 decades (series hybrid like the Infinity e-power) is more efficient and versatile for all terrestrial transport, why is it just now being introduced into cars?
That is an excellent question, and the answer is that it depends on the application.

The gen I Volt is a series hybrid, and it suffered from relatively poor efficiency when running on the gasoline engine. Every time energy has to change forms, there are losses. A series hybrid has this worst case conversion sequence:

Chemical energy in gasoline > thermal energy in engine > mechanical energy > electrical energy > *chemical energy stored in battery > mechanical energy to drive the wheels.

* the battery charging loss is not incurred if the electrical energy is immediately converted to mechanical such as driving a locomotive.

The gen II Volt is a series/parallel hybrid, meaning the mechanical output of the engine can be directly used to drive the wheels. This is more efficient since it undergoes less conversion:

gasoline > thermal energy in engine > mechanical energy powering the wheels

However, ICE engines are only efficient near full throttle and at certain RPM. A 600 HP sport car cruising at 55 MPH is very inefficient since it's running the powerful engine at very low throttle. It's more efficient to have a weaker engine that is capable of supplying just over the amount of power required at cruising speed to run near full throttle (peak efficiency), maintain cruising speed while slowly replenishing the battery for when fast acceleration is needed.

Trains are electric due to the complexity that would be required to have a transmission. Since ICE engines have a small RPM range to operate in, and an even smaller efficiency range, the number of gear changes would not be feasible. Electric motors are capable of a a much higher RPM while retaining power and efficiency throughout the range.

To summarize, an EV is a great choice for trips that don't exceed the range, and ideal for sports cars where acceleration is a primary consideration.

A series hybrid is a great choice for sports cars needing the convenience of petrol station refueling while benefiting from the performance of electric acceleration and retaining the fuel economy of a smaller engine.

A parallel hybrid is best suited for economy driving where the convenience of petrol station refueling is needed, but fuel efficiency is paramount.

To give a human analogy, consider that the body is constantly trying to be as weak as possible to still reasonably function. Adding muscle is like having a larger engine, which is inefficient. The body removes the amount of engine (muscle) that is not necessary in daily life so that it can be as fuel efficient (calorie efficient) as possible. End up bedridden for a period of time and the muscles atrophy to the point of extreme weakness. Trick the body into thinking it needs a larger engine with weight lifting, and it grows it. If only cars were able to biologically adapt to need, they would all be as powerful and efficient as we demand them to be. Stuck in bumper to bumper daily traffic, and it becomes a Prius, or speed on the autobahn, and it becomes a Lamborghini.
 

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If the diesel-electric locomotive model that's been around for over 5 decades (series hybrid like the Infinity e-power) is more efficient and versatile for all terrestrial transport, why is it just now being introduced into cars?
I would only add to redpoint5's excellent reply that for most people, who are not very environmentally motivated, or overly concerned with efficiency, given the US history of cheap gas, they wouldn't be happening. If the OEM's are forced to continue to reduce emissions, and increase mpg, then they will replace straight ICE in almost every vehicle. The required ten or twelve speed computerized transmissions, valve, compression, stroke, fuel mix, and ignition all controlled by computers will make straight ICE too expensive to compete.
 

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Discussion Starter #7
That is an excellent question, and the answer is that it depends on the application.

Stuck in bumper to bumper daily traffic, and it becomes a Prius, or speed on the autobahn, and it becomes a Lamborghini.
Wow! That was an excellent explainer.

So, my old 2000 Ford Focus with manual transmission would be in overdrive at 75 MPH @ 2600 RPM
...on the other hand...
My 2018 McLaren 720S with 7-speed dual-clutch transmission would just be shifting into 2nd gear at 75 MPH @ 8000 RPM (because I typically drive it at the outer edge of the traction envelope...since its all a dream anyway)

Thus the, ...I mean My McLaren is very inefficient when maintaining 75 MPH?

Do you think the Infinity Q EV mission/application is to use such a large battery (if indeed its 20kW) as to pull 100's of kW on-demand at launch, yet transition into a very low current - almost overdrive effect - while simultaneously recharging the battery? IOW, the ICE is sufficient to propel the vehicle Only after its gained momentum from its battery. Is this efficiency enough to achieve 125 MPG?

Why does this sound as if their are some laws of physics being broken somewhere?
 

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So, my old 2000 Ford Focus with manual transmission would be in overdrive at 75 MPH @ 2600 RPM
...on the other hand...
My 2018 McLaren 720S with 7-speed dual-clutch transmission would just be shifting into 2nd gear at 75 MPH @ 8000 RPM (because I typically drive it at the outer edge of the traction envelope...since its all a dream anyway)

My McLaren is very inefficient when maintaining 75 MPH?
Yes, exactly. The Ford focus is more efficient at steady 75 MPH than the McLaren both because it's geared to turn less RPM (less explosions per minute), and because it's nearer to it's peak torque efficiency to maintain 75 MPH than the McLaren. IOW, the Ford requires more of the throttle to be open to maintain 75 MPH than the McLaren does. The Ford is generating the required power to maintain a given speed while using less gasoline compared to the McLaren.

This is a Brake Specific Fuel Consumption map for a Saturn 1.9L engine. It shows various engine speed and torque requirements to generate a given horsepower. The blue numbers on the right show horsepower, and any combination of engine RPM (bottom number) and Torque (left number) along this blue line will produce that same horsepower.

The closer you get to the red island in the middle, the more efficiently fuel is being converted into power. Lower numbers on the colored rings mean lower fuel consumption to produce a given horsepower for 1 hr.

Looking at the 20 HP blue curve on the right, you see that you can make that power at 4,500 RPM and a fuel consumption rate of 400 grams per kWh. Following that 20 HP blue curve, you can make the same power at about 1,750 RPM and a fuel consumption rate of 275 grams per kWh. Same power, less fuel consumption (and much higher torque). That 75% of peak torque line is very close to the sweet spot for efficiency. 80% might be ideal, but you don't lose much by going higher.

Notice you can't even get into the efficient red island without producing a minimum of about 30 HP, with 45 HP being right at about peak efficiency at 75% of the available torque and 2500 RPM.



Here's a graph showing typical power requirements to maintain a given speed. Notice that at 60 MPH, only 15 HP is required, which is nowhere near the 45 HP peak efficiency shown in the graph above. Peak engine efficiency wouldn't occur until about 90 MPH. Don't confuse peak engine efficiency with peak fuel economy though. As the graph shows, the power required to overcome drag increases with the square of speed. It takes 5 HP to drive 40 MPH, but 25 HP to do 80 MPH. That's 5x more power to go 2x the speed (rolling resistance goes up with speed too). What all this means is that the dinky 1.9L, 124 peak horsepower engine in the Saturn is still monstrously oversized to efficiently maintain 60 MPH on the freeway. It would be way more efficient to have a tiny 40 peak horsepower engine powering the car on the freeway, but then it would take an eternity to get up to speed, and the car would slow to a crawl going up hills.



Finally, here is a graph showing electric motor efficiency. At first glance it doesn't look so great, but then notice that efficiency only varies between about 85% and 95% throughout the RPM and torque range. It's pretty darn efficient no matter how hard or fast you run it.



Do you think the Infinity Q EV mission/application is to use such a large battery (if indeed its 20kW) as to pull 100's of kW on-demand at launch, yet transition into a very low current - almost overdrive effect - while simultaneously recharging the battery? IOW, the ICE is sufficient to propel the vehicle Only after its gained momentum from its battery. Is this efficiency enough to achieve 125 MPG?

Why does this sound as if their are some laws of physics being broken somewhere?
All of your assumptions sound correct to me, including doubting the 125 MPG efficiency. My guess is they are stating the MPGe efficiency of the electric drivetrain, just as the Bolt is rated at 119 MPGe. There is no way the gasoline engine can get 125 MPG no matter how efficiently they convert mechanical energy into electrical. The first gen Honda Insight is about the most efficient hybrid car you can find, and it peaks around 70 MPG.

My guess is the car will get about 35 MPG, which is very respectable for a 400 HP, sub 4-second to 60 vehicle.
 
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