Correct me if I am wrong but I think there is an increase in FE even without plugging in due to the electric motor being vastly more efficient than the ICE. As such when the battery pack is depleted and needs to be recharged by the ICE it is still more efficient than the ICE alone. The energy to recharge and drive in EVmode or assisted ICE is overall lower than ICE alone. I see when on the freeway that the ICE and then the ICE and electric motor pulse together off and on. This gives more FE and adds power too. When the assist is pulsing the FE bar jumps about 10 MPG and when it stops the FE bar drops about 7 MPG. This drop is due to the loss of the assist and the load to recharge the batteries too. Since the electric motor is about 2.5-3 times more efficient it adds MPG to the total.

While it is true that plugging in would be even more efficient going hybrid is better than ICE alone.

The best FE seems to be to determine the total daily use without needing to plug in until back at home and design the FEH to deliver within this determination. This would be the absolute best. BUT the design would be different for everyone so there needs to be a compromise that fits the AVERAGE drivers needs. I think this is where the 20-30 miles in EV only mode is coming from. If you could drive to work in EV only and then plug in at work you could effectively double the range with zero added cost beyond the cost of the electricity and some wear and tear on the batteries and mechanicals.

This brings up an interesting thought. If you worked 10 miles from home and could plug in you would still be very FE AND could keep the plug in modification at an overall lower cost. Hence for the 80% yearly use, figured on back and forth to work, it would do all you needed in EV mode and this would be less expensive in the near term. As battery and plug in mods come down in price then the miles in EV mode could extend. This would add others into the fold and make owning an PHEV more palatable.

I think all here agree that, as it is, the EV mode is at best a quiet drive in the parking lot and down a short side street. Give us 10 miles and 40-45 MPH EV mode and we now have a solid EV that delivers some valuable daily use. A little faster and farther makes all the difference in the world.

I want mine yesterday. But not if it is going to cost as much as double what an FEH costs now. This is not viable IMO.

 

AllenF — What you're saying cannot be true. Ultimately, in a round trip, all the energy used by the vehicle comes from the gasoline, including all the energy recovered by regenerative braking. The battery is also sometimes recharged directly by the ICE. But since the mechanical-to-electrical (and electrical-to-mechanical) conversion processes in the motor-generators aren't 100% efficient, and the battery charge/discharge process loses energy to heat too, you are only going to be better off FE-wise by using EV-mode as much as possible if you can arrange things so that battery recharging occurs when the ICE is running at greater efficiency than it would otherwise have been achieving had you not used EV-mode. This can apparently be done in the FEH more easily than in some of the other hybrids out there, whose ECUs optimize overall FE somewhat better. However, your assumption that you are increasing FE simply by using EV-mode more, is false.

Stan

 

OK. Here is how I see it and I don't know what the numbers are but here goes.....

Electric motors are much more efficient than ICE's are. But the load on the ICE is far less when recharging than when pulling the car through the drive train. Therefore the electric side of the FEH is using much less than the ICE when powering the wheels.

This is why trains and large ships are diesel electric. The diesel engine can be much smaller because it is used only to turn the generator which in turn powers the electric motor(s). Since the electric motor needs about 1/3 the energy that an similar piston engine would need to do the same work it is cheaper and more reliable to go diesel electric than it is to go purely mechanical diesel. On boats and trains there are far fewer start/stop cycles so they are more or less run at a constant speed and are well suited to these electric powered systems too.

In the case of the FEH, or any auto, we have many hills and start/ stop cycles so the hybrid system seems to be better suited for these types of operating conditions.


When you look at pure electric motors versus ICE's electrics are far more efficient with energy used thus they will go much farther on a gallon of BTU's than any other method out there .


Put another way. If it takes 360 watts to go 20 MPH for about a mile and there are 100 times that in one gallon of gas then if we had that level of energy storage in the battery pack we could go 100 miles on one gal of gas. I know of no ICE that can push this 3800 lb SUV at 20 MPH for 100 miles In fact I would think it would be hard to get much better than 60 MPG in a purpose built engine/drive train.

How I arrived at 360 watts was to take a fully charged battery pack which holds 1.8 KW and used 20% since this seems to be what most here are saying this gives you 360watts. Most here also think you can drive about 1 mile without to much trouble at 20MPH. If I am off then adjust accordingly. But even if I am 100% in error it still works out to be 50 MPG. This is still far greater than any ICE could do. How it does this is due to the electric using nearly all of the energy in motion and very little lost to heat and friction.


The ICE when recharging is under a lighter load than when it has to push the whole truck so it uses much less gas. Since the electric motor uses about 1/10 the energy, maybe even less, that the ICE does to do the same work the electric motor will ALWAYS have better FE EVEN when it's battery needs to be recharged by the ICE.

The Ice recharges VIA the 45 KW generator. The electric motor is rated at 70 KW MAX load/power. Usually it is using much less than this hence why 360 watts can get you down the road about 1 mile at 20 MPH.

The real gains come when you plug in and thus keep the ICE off all or almost all of your drive to work. Since electricity costs about 1/3 for the same amount of electricity generated by the ICE, you can really save some money buy plugging into the grid and also send that tail pipe far from the crowded city.

 

No, trains are diesel electric because they require extremely large amounts of torque to get them moving. Electric motors have large amounts of torque when starting, which make them uniquely ideal for the application.

Gas and diesel engines have like no torque at 0 rpms.

 

AllenF — I was, of course, commenting on the first paragraph of your earlier post (#11); this concerned HEVs and not PHEVs. Yes, the electric motors are far more efficient in converting electrical-energy-in to mechanical-energy-out than an ICE is in converting chemical energy in the gasoline into mechanical energy, but the energy input to the motor comes ultimately from the ICE anyway, and so the electric system simply adds an additional (small) energy loss to the system. The reason this can be beneficial from an FE point of view, is that the HEV design allows the ICE to be run in a generally more efficient regime than is normally the case in a non-hybrid. And, of course, the facts that the ICE is frequently "off" when it's not needed (as when idling or coasting, for example), and significant kinetic energy is recovered as charge in the battery (instead of being wasted as heat, as would otherwise be the case) when braking, are additional major factors that increase the in-town FE of an HEV. But you don't get energy for free, and every single kWh of energy used came ultimately from the ICE (and thus from the gasoline), and so includes its very significant losses. By the way, an ICE is very inefficient at low power outputs, and so the argument in your latest post for recharging the battery with the ICE running at low power wouldn't result in high FE, but the opposite.

Stan

 

Walt are you saying that Diesel electric is torque based only and not more efficient? If so I disagree. A simple Google will so this so.

Stan whether or not in it's most efficient mode the lower load will use less fuel. How much is not available to me but I arrived at this using common sense. Idle you lawn mower and try to cut the lawn verses rev it up and do some work. Which one works better? The same for the FEH ICE driving the 45KW genny is easier than the whole SUV. If Ford used a bigger motor and battery pack we most likely could have the gas electric all electric SUV in stead of what we have now. I think cost was the over riding factor hence what we have now. All speculation on my part but I see a small efficient Diesel driving a generator which runs the electric motor as being something worth looking into. You would use the battery pack to add power for starts and hills and passing. Otherwise the genny would power the motor. Not new just different and perhaps better.

Since Ford is already installing the ICE in non FEH it makes better $$$$ sense to modify what they already have and thus what we end up with.

Starting with a clean sheet of paper could have given us an even better product but cost keeps all things in check.

One last point run the ICE at it's best and worst case of FE and I bet it is not that big of a difference as in either case the ICE is very inefficient compared to the electric motor.

 

AllenF — I'll try one last time! You can't get something for nothing. All the electrical energy that the electric motor uses (included regenerated energy from braking) can be traced back to energy originally produced by the ICE from burning gasoline. Having a very efficient electric motor can't overcome the fact that the electrical energy it uses has already been subject to losses in the ICE (and also the battery, if involved) — all it can do is reduce the extent of the further energy loss. There's no perpetual motion machine; the laws of physics are immutable! Yes, running the ICE at low power will burn less fuel, but it will also correspondingly do less work! Its efficiency could also drop by a factor of two! The demand on the vehicle will dictate moment by moment the work that the ICE needs to do. And the work that it does will use more gasoline per kWh of work done if it's run inefficiently. The whole science of hybrid ECU programming is to maximize the moment by moment efficiency of the ICE, within the limits imposed by the parameters of the system.

Stan

 

Stan I see your point however I think you missed mine so I too will try once more.

If it takes 1/4 gallon to go 10 miles using the ICE ONLY and this is due to it's inherit inefficiency I think that those same KW's are better put to use in powering an electric motor which even being charged by the ICE will go farther due to it's HIGHER efficiency.

As you pointed out all one can do to make gains in FE is to capture energy lost to inefficient technology. This is what the electric motor does in part. So what I said in my earlier posts holds up. Using better technologies to do the work yields better FE.

 

I think you two are talking about two sides of the same coin - you're just trying to use different arguments about the same thing.

You're actually both right.

But diesel electric engines are used on trains because of the better torque curve of the electric motors. On hills and from a standstill, with trains with a couple of million tons of load, they just would not be able to pull a load well if they had to try to work off gearing down from a direct shaft from a diesel motor. There's just not enough low end torque to get a decent sized construct (locomotive/car combinations) moving. That's part of the reason the switch from steam engines to diesel-electric happened so fast. Steam locomotives were very limited in their total load capacity (usually only about 15-20 cars max) because of their poor ability to get going from a stop. Diesel-electric constructs can easily run into 100 or more car combinations nowdays.

The limitations they have been running into in the last couple of decades on the length of the constructs are not the power of the locomotives but the actual length of the string of cars itself. When they have to slow down to go through towns, a long string of cars tends to **** off the townspeople when they have to wait at the crossing for 15 minutes to let the train go by.

 

[quote=AllenF;161588]

If it takes 1/4 gallon to go 10 miles using the ICE ONLY and this is due to it's inherit inefficiency I think that those same KW's are better put to use in powering an electric motor which even being charged by the ICE will go farther due to it's HIGHER efficiency.

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Let's do the math. To avoid mixed units (watt-hours, horsepower, BTU,
joules, calories, whatever), let's make up a universal energy unit I'll call
"Noodle" which applies to both electric and ICE domains. Suppose the ICE is 25% efficient and the electric motor is 75% efficient at converting Noodles into motion, across their entire operating range. These are simplifications, obviously.

Let's say it takes 100 Noodles of energy at the wheels to accelerate our car to 30 MPH and travel 1 mile, accounting for air and tire friction.

For the pure electric case, at 75% efficiency, it will require 100N/.75 = 133 noodles of electricity to make that happen.

For the pure ICE case, at 25% efficiency, it will require 100N/.25 = 400 Noodles of gasoline.

For a series hybrid, where the ICE drives a generator which drives the electric motor, you have two levels of loss -- the ICE loses 75% and the motor loses 25%. To get the 100 noodles kinetic energy on the road :

You already need 133 Noodles of electricity to drive the 75% efficient electric motor, and to generate that much electricity from the ICE, you need 133/.25 = 533 Noodles of gasoline (vs. 400 Noodles in pure ICE drive). As someone noted, there is no free lunch. This requires more energy this way; the total efficiency is now only 100/533 = 19%.

There are proposed "Range extended electric vehicles", which are plugin EVs with
auxiliary ICE generators (the ICE doesn't drive the wheels, only the generator). The way I see it, the only potential advantage over hybrids is that the ICE doesn't need to be big enough to accelerate the car up a mountain road; instead of a 150 HP ICE, you can run a smaller and lighter one at a constant load to charge the battery and run the electric motor. I suppose you could run the generator in the parking lot while you were in the grocery store or meeting with your clients. Anyhow, the whole idea sounds too kludgy to me.