EREV - A Horsepower Math Problem?

[Lytning]

Based upon the early lack of information ( ) on Ford's announced (soon!) EREV truck, I sense the existence of a pending horsepower math problem.

Assume the truck is towing a fairly heavy, non-aerodynamic trailer. After about 150 miles the EV battery will be depleted, assuming no contribution from the ICE component of the EREV. Even with an ongoing ICE contribution, at some point the EV battery will be depleted. When the EV battery is depleted, assume the truck is running solely on the ICE component.

How much ICE-only horsepower will be required to tow the trailer at highway speed, on an incline, with a headwind, and maintain the set speed?

The ICE component of an F-150 PowerBoost has 394 HP. The ICE-only 2.7 liter V-6 EcoBoost has 325 HP. One can assume that this range of HP is what is required for acceptable performance while towing a heavy trailer. Even assuming the ICE component of the EREV will operate continuously with an ongoing "assist" from the EV battery component, I would guess-timate that a minimum of a 200 HP ICE component would be required to maintain even minimally acceptable performance. For comparison, a Prius has a 2 liter 4 cylinder engine with 194 HP, and you are not going to haul a heavy trailer with that.

So, it seems like the EREV will essentially be a PowerBoost with a smaller ICE component and a larger EV battery component ... and @Ford Motor Company marketers decided to call it an EREV instead of a Hybrid variant. (Ford does state that the EREV truck will be driven by electric motor(s), but it is still a Hybrid variant to me.)

It will be interesting to see what the ICE HP will be in the EREV / Hybrid, and its detrimental effect on equivalent mileage ratings versus our BEV trucks. And, I don't see anywhere else to hide a 200 HP or more ICE other than the frunk.

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[Quibbs]

The proposed EREV ICE engine is not connected to the powertrain. It is solely a generator to charge the battery. It is not a typical hybrid in the sense that it is a ice engine assisted by battery power but it is more a battery system assisted by a ICE engine to keep the batteries powered below a certain level.

The problem for Ford is there is really no logical case that this new variant of the lightning will be cheaper than the pure ev. Unless Ford greatly reduces the size of the battery. Which would mean the generator would be running a ton. You could argue in a sense it is a hybrid but that's not the way they are pitching it. They are selling it as an EV with more range. I would bet the price, if this thing gets released (if**) will actually be higher than the pure ev lightning. Which would imply Ford thinks it can sell more because of the addition of a generator.

Ford made initial market assesment mistakes in gearing up the original lightning. Building a system based on a 100k a year projection. They basically put themselves in a position to be bullied. Bullied by the current regime in charge, bullied by it's dealer network, bullied by large stockholders.

 

[reddog21]

You're never running off the engine; it's strictly a generator. Your always running off the batteries
The engine-driven generator does produce horsepower but that power is converted into electricity, not sent mechanically to the drivetrain. Your entire drive train is going to be very similar to the Lightning.

 

[reddog21]

Which would mean the generator would be running a ton

Why, the truck will plug in just like it does now. If you use Ram as the baseline your looking at 145 miles per "charge" without the generator.

 

[Timeless Epoch]

The proposed EREV ICE engine is not connected to the powertrain.

Sure it is. It is electrically coupled. It’s not like you’ll deplete the battery and the truck comes to a stop.

 

[Athrun88]

I would imagine the ICE component would be able to generate sufficient power to charge the HVB as you drive since it's not directly connected to the drivetrain. It's acting as a generator to supply power to the HVB which in turn drives the wheels. There is no "ICE only" mode unless you intrepret that to mean the ICE portion runs to charge the batteries on the go.

 

[mr.Magoo]

Sure it is. It is electrically coupled. It’s not like you’ll deplete the battery and the truck comes to a stop.

I mean, duh...
Otherwise it would be like a portable generator where you'd have to pull over, plug it in and charge, which would be kind of dumb, so yeah it is connected (electrically) to the powertrain.

He was probably referring to a mechanical (gearbox, driveshaft, etc.) connection to the wheels.

 

[reddog21]

I think people are overthinking this concept, it's basically going to be the exact same lightning except you have an onboard generator which has the sole purpose of charging the batteries. I'm making the assumption(maybe stupidly) that's it's going to be based on the same concept at the Ramcharger.

Electric motors drive the axles
No mechanical connection between the generator and the wheels
Single-speed reduction gears (no transmission)
Regenerative braking
Drives like an EV at all times

 

[Timeless Epoch]

I mean, duh...
Otherwise it would be like a portable generator where you'd have to pull over, plug it in and charge, which would be kind of dumb, so yeah it is connected (electrically) to the powertrain.

He was probably referring to a mechanical (gearbox, driveshaft, etc.) connection to the wheels.

I don't know what was in his head, only what he posted. There will be scenarios where the gas engine is not only the primary source of locomotion, but charging the battery. So to say the genset is not connected to the drivetrain and is "solely a generator to charge the battery", is fundamentally wrong.

 

[Altivec]

and you don't think that is going to be major wear and tear on a smaller battery. I know my ELR Erev took a beating and the battery is ready to be replaced at under 75k miles.

 

[carys98]

The Ram EREV is planning for a 3.6 liter V6, basically a non-turbocharged version of the standard Ram 1500 engine. That plus a battery that is almost as big as the Lightning SR pack. The Lightning is going to need something similar so they’ll probably use some form of the 2.7 or 3.5. Turbocharging and variable valve timing isn’t as important for a generator application since you can run at a constant RPM so you can just optimize for that. That should help reliability but even a base engine is going to be expensive. I’d like to see the math where you can be profitable with an engine, a generator, and an SR pack but you can’t be profitable with an ER pack.

The only good thing about these EREVs is that it will show people that they are a terrible idea for the vast majority of users.

From the Ram website:
“The All-New Ram 1500 REV delivers innovative performance with a liquid-cooled 92-kilowatt-hour battery pack paired with a 130-kilowatt generator. The 3.6L Pentastar® V6 engine generates mechanical power, which is converted to electrical power by the onboard generator for maximum efficiency. The generator can also increase the power to the motor and gearbox when serious power is needed.”

 

[sotek2345]

The Ram EREV is planning for a 3.6 liter V6, basically a non-turbocharged version of the standard Ram 1500 engine. That plus a battery that is almost as big as the Lightning SR pack. The Lightning is going to need something similar so they’ll probably use some form of the 2.7 or 3.5. Turbocharging and variable valve timing isn’t as important for a generator application since you can run at a constant RPM so you can just optimize for that. That should help reliability but even a base engine is going to be expensive. I’d like to see the math where you can be profitable with an engine, a generator, and an SR pack but you can’t be profitable with an ER pack.

The only good thing about these EREVs is that it will show people that they are a terrible idea for the vast majority of users.

From the Ram website:
“The All-New Ram 1500 REV delivers innovative performance with a liquid-cooled 92-kilowatt-hour battery pack paired with a 130-kilowatt generator. The 3.6L Pentastar® V6 engine generates mechanical power, which is converted to electrical power by the onboard generator for maximum efficiency. The generator can also increase the power to the motor and gearbox when serious power is needed.”

Yeah, I don't know how the math works unless they drop to a much smaller battery pack (40-60 kwh LFP? - maybe the base Mach-e pack?). With the smaller pack, I don't see how a naturally aspirated V6 engine put out enough juice to keep it charged while delivering enough power. I also have to question if making a bespoke optimized engine for the EREV makes sense economically either. They might just use one of the standard F150 engines and tweak the programming.

 

[RLXXI]

I don't know what was in his head, only what he posted. There will be scenarios where the gas engine is not only the primary source of locomotion, but charging the battery. So to say the genset is not connected to the drivetrain and is "solely a generator to charge the battery", is fundamentally wrong.

That's not how Ford is pitching this though, they are saying it'll be a generator to ONLY charge the battery. There is no physical/ mechanical connection and the vehicle will not run on the generator alone.

 

[RLXXI]

Yeah, I don't know how the math works unless they drop to a much smaller battery pack (40-60 kwh LFP? - maybe the base Mach-e pack?). With the smaller pack, I don't see how a naturally aspirated V6 engine put out enough juice to keep it charged while delivering enough power. I also have to question if making a bespoke optimized engine for the EREV makes sense economically either. They might just use one of the standard F150 engines and tweak the programming.

Generator that puts out that much kW likely won't fit in the truck. I have a 1.0L v twin 18kW Generac in my back yard to power the home when the grid drops, it's fairly large, it would take up at least half the bed space.

 

[LiteNing]

The ICE component of an F-150 PowerBoost has 394 HP. The ICE-only 2.7 liter V-6 EcoBoost has 325 HP. One can assume that this range of HP is what is required for acceptable performance while towing a heavy trailer. Even assuming the ICE component of the EREV will operate continuously with an ongoing "assist" from the EV battery component, I would guess-timate that a minimum of a 200 HP ICE component would be required to maintain even minimally acceptable performance

Sounds right to me. I look at the math like this: Assume you want to drive up a 6% grade at 65 mph with a total rig weight of 15000 lbs. I’m going to do everything in metric because that makes the math easier:

6800 kg * 9.8 m/s/s * 0.06 * 100 km/h =111 kW = 150 hp

At 65 mph we get around 1.9 kWh/mile on flat ground without a trailer, so that’s another 34 kW =45.6 HP of aero drag. With a trailer I’d guess more like 1.5 kWh/mile, so call it 60 HP.

So altogether (that’s an entirely different kind of flying!) that comes to just shy of 210 hp.

Of course, you only need that much power to continuously climb a grade and maintain the battery SoC. If you’re going up and down, you get to regen on the downs to build a buffer for the way up. You can also go faster if you’re willing to deplete the battery as you climb (maybe with a “mountain mode”, like in the Volt/ELR, that targets 50% SoC instead of 10% for the engine start point).

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