EREV - A Horsepower Math Problem?

[Newton]

Because you dont have to run the battery to minimum SOC. Thats just computer logic to balance generstor output and battery output. Ultimately though the battery HAS to be available, the demand placed on the system is highly variable and the battery provides that variation.

No reason that at 50% SOC the generstor kicks on full time, and at 25% SOC speed and acceleratiin are limited. Or 75% and 50%. After that its just giving the drivers some settings to bias the system one way or another.

I agree that if you want any kind of decent performance the battery has to be available, but I'm not sure that is what happens.

If we want to speculate about these systems we need to know the output of the generator in kW, and we don't know it for either of the two EREV truck systems that are in or close to production. You cannot know this from the HP rating of the gas engine, as I have said often.

So, consider this to be wild speculation based on some knowledge. I believe that the Ramcharger is a 30kW system based on some information and speculation. In one report, I read that they can send 30kW to a house in an emergency. The Pentastar V6 has a displacement of 3.7L which would be too small for a 50kW Diesel generator (4.5L for this 50kW) but about right for approximately a 30kW generator. I know that I am comparing different technologies but a diesel engine will always be capable of more torque than a similar displacement gasoline.

I also looked at the dimensions of the Ford Ecoboost V6 which I think is the largest engine that fits in the F-150 compared to the dimensions of the diesel generators and again, roughly 30kW is all that I think can fit. This is of course very speculative and rough but I'd say that 30kW is in the ballpark and even trying to get that much from a gasoline engine that is specifically designed to be light is ... bold.

If we use 30kW as a benchmark then we can go even further out on the speculative limb to see what the managers are thinking while the engineers cringe. The Lightning is rated at about 2.6 mi/kWh from the EPA (Lariat 320mi/131kWh). At that rate, one hour of driving will generate a (absolute maximum) of 78 miles of charge so if you keep it under 80 you can drive as much as you have gas in the tank + the electric range.

Unfortunately it is not that simple, beginning with the fact that I rarely see numbers that high and certainly not when towing. Additionally in the heavy towing cases that the EREV is supposed to solve, the battery will be hot which limits how much charging you can do.

The really hard problem to solve is that 30kW is not going to drive the electric motors very well, and while it is driving the motors it is not charging the battery. So once the battery is down it stays down until you fast charge. The assumption when they say things like "700 mile combined range" is that you can just go to a gas station and fill up - but that is not true. You will have to go to both a gas station and a charger for the next leg of your 1400 mile trip.

To make this work as a driver, I think you are going to have to be very aware of your current usage, expected usage, and plan on turning on the 'charger' much earlier than you think - probably at the beginning of your trip. For customers who already have difficulty with route planning ("just use ABRP!" we say so often) this is going to be even more off-putting.

The really big question for me is "how well does it drive with the battery completely empty?" Can I tow my (imaginary) big rig up Washington Pass, and at what speed?

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[hturnerfamily]

yes, those are agreed points that most of us have little to go on, at least yet...

from the very beginning, an advertised '700 miles Combined range' can be a little misleading, at least to those unaware of all the REAL elements to this idea. I doubt that anyone assuming that you can then drive 80+mph on the Interstates for the whole 700 miles is going to be pleased with the 'real' outcome... they'll be stopping to fast charge about 200 miles in. They'll have seen the battery SOC dropping like a rock, and yet the Generator is, yes, running. Still, it won't look good, and range anxiety will still be a thing.

You can get range anxiety at 50 miles in, and you can just as easily get it at 300 miles in.

A Generator that could possibly drive the vehicle at the same speeds and for the same miles might as well be your ONLY power source, since, well, WHY then would you need a battery??

The Generator's ONLY job is to recharge the battery pack. It is NOT to drive the truck.

 

[chriserx]

A Generator that could possibly drive the vehicle at the same speeds and for the same miles might as well be your ONLY power source, since, well, WHY then would you need a battery??

To run HVAC at a stop, to store regen braking, to store 'excess' power generated, to enhance efficiency by running the generator at it's most efficient output, to combine battery power and gen power in a way some supercars have for performance reasons. And this is just what I came up with in under a minute, imagine what an actual engineer could with time. I don't disagree with your sentiment, just playing devils advocate.

 

[hturnerfamily]

To run HVAC at a stop, to store regen braking, to store 'excess' power generated, to enhance efficiency by running the generator at it's most efficient output, to combine battery power and gen power in a way some supercars have for performance reasons. And this is just what I came up with in under a minute, imagine what an actual engineer could with time. I don't disagree with your sentiment, just playing devils advocate.

I don't disagree, but my point was actually just the premise that the Generator is somehow going to 'drive' the truck when the battery is low or depleted... or, maybe just when the owner WANTS to drive it that way - otherwise, that's called a HYBRID, like we've had for years.

If a generator/engine that can be placed within the Frunk and will be a large enough and consistent enough to power the truck down the road, then why not not just have a token 10kwh battery pack, or just a 1kwh battery pack... you'd be mostly relying on a generator/engine running 100% of the time.

I DO, though, disagree with the premise that the Generator/engine is going to be powerful enough to power the truck at 100% torque and hp you might expect... sounds like any 'generator power' directly to the motors will be simply for SUPPLEMENTAL support, with the battery output already at a HIGH output, for steep terrains and heavy loads, etc.
I'd like to be proven wrong, and that's o.k. if so... I'm good for knowing more exact ways and equipment involved in powering such a vehicle.

 

[chriserx]

I don't disagree, but my point was actually just the premise that the Generator is somehow going to 'drive' the truck when the battery is low or depleted... or, maybe just when the owner WANTS to drive it that way - otherwise, that's called a HYBRID, like we've had for years.

If a generator/engine that can be placed within the Frunk and will be a large enough and consistent enough to power the truck down the road, then why not not just have a token 10kwh battery pack, or just a 1kwh battery pack... you'd be mostly relying on a generator/engine running 100% of the time.

I'm not against what they're attempting even if I think it's a bit backwards, but it would allow them to maintain our software while getting potentially more sales from more traditional truck drivers and act as a bridge for nascent solid state battery tech to mature. I feel strongly that 50 kwh usable would be the sweet spot for this type of truck, a decent EV only range, decent buffer. Ford is likely going to aim for the current truck use average for its EV mark which is local trips, non towing and maybe 500-1000 lb load, 25 kwh would be good enough for this. But for EV marketing and a decent battery life expectancy I'd expect around 50 kwh

 

[Lytning]

Because you dont have to run the battery to minimum SOC. Thats just computer logic to balance generstor output and battery output. Ultimately though the battery HAS to be available, the demand placed on the system is highly variable and the battery provides that variation.

No reason that at 50% SOC the generstor kicks on full time, and at 25% SOC speed and acceleratiin are limited. Or 75% and 50%. After that its just giving the drivers some settings to bias the system one way or another.

I understand that the generator would start at a mid-level SOC to add kW to the HV battery and extend range. But, I can also envision in a heavy towing situation where the HV battery, even with generator input, could drop to its minimum allowable SOC. At that point, the vehicle will either stop, or continue under power provided only by the generator (either through the HV battery, or bypassing the HV battery).

 

[Mal106]

If i were Ford I'd just take the Ecoboost 3.5 truck and replace the 10 speed with whatever generator could use it's max power and let it power the current lightning drive train. Then stuff in as much battery as the chassis could carry and still have 1500 to 2000lb payload.
Tune the 3.5 for generator operation and let software give you what you need and when. Defeciencies in EPA range that happen due to battery size can be made up with fuel tank size.

 

[grottomatic]

I don’t see why they don’t just make a big battery 2.7 ecoboost plugin hybrid. The 2.7 is a great engine, proven performer with high reliability that has been accepted by fleets-but needs more towing power, which they can get with electric on the driveline. I think they will ditch the current powerboost and work on a hybrid that can actually have the battery buffer to help with towing, and the battery only range to get you at least to work (30-40 kWh). The current powerboost has a tiny battery that is gone about half a second into towing a grade and then you get the poor economy of a 3.5 twin turbo on full blower.

I think the EREV is going to be too expensive and too heavy for the benefits without massive breakthroughs in battery weight and efficiency losses with genset operation. There will be massive warranty issues.

Without absolutely stunning performance out of the generator and DC bus (I don’t think you can get away without the ability for the generator to provide massive power directly to the motors in a towing situation) the solution doesn’t make a lot of sense for something early marketing tells us is going to “tow like a locomotive.”

 

[ZeusDriver]

I'm trying to wrap my brain around some type of 400+volt generator... give me some examples of some, especially something that would fit in the frunk area.

Surely you jest. The drive motors of the current Lightning are 400 volt generators. The rotors are 8 or 9 inches across. Every electric motor is simultaneously a generator. (There can be vey slight tweaks to an electric machine to make a motor better at generating, but these are extremely subtle.) In my little PHEV (EREV in todays words) prototype, the drive motor and the generator were exactly the same, and the motor provided propulsion at 91% efficiency and generated at 91% efficiency. In this application, the total generating process was actually just slightly more efficient than the drive process, because there was nothing electronic controlling the generator. In other words, there was just a contactor (a heavy switch) and heavy wires between the generator and the batteries (Whereas the drive motor was controlled by a fancy version of pulse width modulation.)

Some concepts are more easily understood with a brushed permanent magnet motor. You can probably guess that such a motor has a particular maximum speed when fed by e.g. 12 VDC. Suppose you have no load on the motor. What keeps it from going faster and faster and then flying apart from centrifugal effects? The back emf generated by the motor as is runs increases with speed. At the point that the back emf and input voltage are the same, then there is no difference in voltage, thus no flow and thus no further acceleration.

If you read about the Ram EREV truck, you will see that there is no starter motor. There was also no starter motor in my little protype. The generator was the motor that started the engine.

This article explains back emf: https://en.wikipedia.org/wiki/Counter-electromotive_force

 

[ZeusDriver]

If i were Ford I'd just take the Ecoboost 3.5 truck and replace the 10 speed with whatever generator could use it's max power and let it power the current lightning drive train. Then stuff in as much battery as the chassis could carry and still have 1500 to 2000lb payload.
Tune the 3.5 for generator operation and let software give you what you need and when. Defeciencies in EPA range that happen due to battery size can be made up with fuel tank size.

I imagine that's not too far from what they will do. I doubt that they will use the engine in ecoboost configuration, because they can probably get better thermal efficiency by making it Atkinson cycle, and the engine can be simpler and lighter and cheaper and longer-lasting without the turbo and its controls.

Using the Lightning truck layout would probably work better to retain the two motors, the independent rear suspension, and the space for batteries (that not having a drive shaft allows). There may be enough room to put the engine above front electric motor, if the oil reservoir were mounted remotely.

I think they will limit the battery pack size to control cost. 150 mile EPA range at 2.2 m/kWh would be about 70 kWh pack, with the reduction in size from an SR lightning pack being about enough to offset the engine weight. The remaining 550 miles could come from a 25 gallon tank at 22 mpg. Making the pack smaller than 70 kWh would make it difficult to get the desired HP output from the motors.

 

[ZeusDriver]

I don’t see why they don’t just make a big battery 2.7 ecoboost plugin hybrid. The 2.7 is a great engine, proven performer with high reliability that has been accepted by fleets-but needs more towing power, which they can get with electric on the driveline. I think they will ditch the current powerboost and work on a hybrid that can actually have the battery buffer to help with towing, and the battery only range to get you at least to work (30-40 kWh). The current powerboost has a tiny battery that is gone about half a second into towing a grade and then you get the poor economy of a 3.5 twin turbo on full blower.

I think the EREV is going to be too expensive and too heavy for the benefits without massive breakthroughs in battery weight and efficiency losses with genset operation. There will be massive warranty issues.

Without absolutely stunning performance out of the generator and DC bus (I don’t think you can get away without the ability for the generator to provide massive power directly to the motors in a towing situation) the solution doesn’t make a lot of sense for something early marketing tells us is going to “tow like a locomotive.”

I think the hitch with 30-40 kWh is getting adequate HP from the batteries. The SR Lightnings have a lower HP rating than the ERs because the battery pack is smaller. A parallel hybrid of your description would work well, but that is no what Jim Farley described.

The Ranger PHEV (in non US markets) has both very limited range and very limited performance in the electric-only mode. I think with the Ram EREV having the lead, that Ford will have to bring out something similar.

 

[PJnc284]

I think with the Ram EREV having the lead, that Ford will have to bring out something similar.

yup. There's a reason they said 700 miles to 1-up the Ram.

 

[ZeusDriver]

Lots of ways to find efficiency. For example, in the winter, running the generator because it generates waste heat that can warm the cabin and battery. Is that more efficient than using resistive heating?

The Chevy Volt did this. The efficiency (if measured in terms of equivalent kW input -- fuel value -- vs kW output of the heater) is much lower with the engine running. If the heating element is fully contained in the thing that you want to heat, then any electric heater is 100% efficient -- there is no "waste heat". An engine as a waste heat generator is not great, because a lot of heat goes out the exhaust, and a lot is radiated from the engine block, exhaust tubing and catalytic converter. Things improve if there is otherwise a need to run the generator, however.

In the volt, it appeared to me that comfort was the entire motive -- it was only in very cold weather that the engine would start up for that reason.

 

[mr.Magoo]

https://pmgenerators.com/dc-generators/

Probably end up with something similar to this. These guys have custom models that would offer 80kW and 400V and mounts directly to the flywheel.

 

[grottomatic]

I think the hitch with 30-40 kWh is getting adequate HP from the batteries. The SR Lightnings have a lower HP rating than the ERs because the battery pack is smaller. A parallel hybrid of your description would work well, but that is no what Jim Farley described.

The Ranger PHEV (in non US markets) has both very limited range and very limited performance in the electric-only mode. I think with the Ram EREV having the lead, that Ford will have to bring out something similar.

That’s interesting, didn’t know there was a Ranger PHEV. I was thinking they would transition to the 2.7 for the next gen powerboost model with a bigger battery and possibly better efficiency. With a larger electric motor (I think the current one is -45hp) there could be more torque fill to help with towing power and efficiency which is the weakness of the 2.7 (very little torque out of boost at lower rpm). With a bigger battery you could naturally get better range- at steady state unloaded.

At highway speeds a 100hp electric motor would be fine for ICE shutdown.

I’m assuming the EREV and any new power plant (hybrid/ice) will come with the updated truck in 2028 thus have a new frame and probably suspension.

I’m not as knowledgeable about this stuff as you though. Seems like the 3.5 may be overkill for a future power plant.

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