Lightning vs. EREV Lightning

[ZeusDriver]

BTW, most of us get about 2.2 miles per kWh at 60 mph.
Also, most of us either have (or have imagined) about 1.0 miles per kWh when towing a medium-sized trailer.

That means that, in the first case, power into the motors is 27.27 kW. Given .93 efficiency, power out of the motors is 34 HP*.

In the second case, power into the motors is 60 kW. Given .93 efficiency, power out of the motors is 74.8 HP.

SO:
If the continuous output of the EREV's engine is 150 HP, and that engine is directly coupled to a .93 efficient generator, then the generator will supply 150*.746 = 111 kW. That means that the duty cycle during towing the load above would be about 54%. Easy-peasy.

If you have found that towing with your Lightning gives you .5 miles per kW, then you might have to hope for a little larger engine in the EREV-- or buy a diesel.

Of course, the engine and generator will also have a peak rating, so it would take a very unusual condition to require the driver to slow down. "Locomotive" is a nebulous term, and the standard towing capability test only requires something like 40 mph, so there is quite a bit of wiggle room, and also quite a bit of room for arguments between marketing and engineering... which is probably what has happened at RAM, resulting in delays in their EREV.


* In the US, and in many other countries, the convention has been to specify motor input power in watts (or kW) and output power in HP. In Europe, engines (such as car and truck engines) are specified in kW, as are electric motors. The reason for the convention in the US is that power calculations for running industrial equipment involve pounds force and speed, with one HP being 550 ft lb/sec. So the mechanical engineer goes to the electrical engineer, and says "I need a 5 HP motor, referring to the motors output (which becomes an input into his machine). Motor efficiency is the ratio of output power to input power, so, for example, a 5 hp motor of average efficiency (.80) will have an input power of 5/.8/*.746 = 4.66kW.

In Europe, when an engineer specifies a 4660 watt motor, the vendor has to ask "Do you mean input power or output power?"

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[ZeusDriver]

More Bloviating!:

We sometimes think that rational minds direct engineering at the auto companies. However, Elon Musk is not the only lunatic out there. He tells the people working for him that instead of using real rain sensors to make their automatic wipers work, they must do it with just the cameras used for driver assist systems. The auto wipers have never worked, as a result. Likewise "Full Self Driving" has never been "Full" despite promises every year for the last decade that the system would "fully" drive the car without intervention. Many engineers who have worked on autonomous driving for longer than Tesla has agree that radar and lidar are both useful additions to cameras.

People rise through organizations until they reach their level of incompetence. (Reread "The Peter Principle") So, will Ford get the EREV right? Maybe. Was ditching the Lightning (because they did not sell "enough", even though far more Lightnings were sold than Raptors? Maybe. Has the stock shown steady growth, the sign of a well managed company? No.

Many of us think that ditching the Lightning is a mistake, because it is a really nice truck is so many ways. Perhaps, however, some of the Lightning people will be working on the next trucks, and perhaps we will be singing the praises of those trucks in a few years. We can dream.

 

[djwildstar]

If the continuous output of the EREV's engine is 150 HP, and that engine is directly coupled to a .93 efficient generator, then the generator will supply 150*.746 = 111 kW. That means that the duty cycle during towing the load above would be about 54%. Easy-peasy.

"Locomotive" is a nebulous term, and the standard towing capability test only requires something like 40 mph, so there is quite a bit of wiggle room, and also quite a bit of room for arguments between marketing and engineering... which is probably what has happened at RAM, resulting in delays in their EREV.

Yes, exactly.

A typical automotive gasoline engine offers maximum efficiency at about 70% to 75% of peak power; a typical generator hits its maximum efficiency at about 85% of its peak power. So I suspect that Ford will use a naturally-aspirated Cyclone/Duratec 3.5L V6. This is a relatively cheap and reliable engine that outputs a peak of 265 horsepower (198kW) on regular gas.

So running it at 70% of peak power would provide 138kW input to a 165kW alternator. The alternator would output about 127kW, which needs to go through power electronics (estimated 95% efficency) to provide roughly 120kW at the correct voltage and current to charge the battery or run the drive motors.

Assuming that the worst-case towing scenario roughly aligns with your 0.5 mi/kWh worst-case estimate, this means that the EREV's ICE engine can keep the battery state of charging from dropping even in a worst-case towing scenario. In almost every other regime, it'll provide a net increase in battery state of charge. So there's probably very little need for a peak power mode, and some efficiencies to be gained by optimizing the entire engine-generator set to run only at a single fixed most-efficient speed.

Very roughly, I'd estimate 18-20 MPG for gas-powered miles. This isn't out of line with the rest of the F-150 line-up, which gets highway mileage between 18 MPG (Raptor) and 26 (EcoBoost). The lack of CAFE penalties -- and the EREV's prioritization of electric-only daily driving -- means that the gas mileage is largely irrelevant as long as it is "good enough" that buyers don't balk.

I have heard that for the RamCharger/Ram REV/PHEV/EREV truck, Stellantis has been trying to get their 3.6L Pentastar engine modified to run the Atkinson cycle to offset the efficiency losses imposed by multiple conversions in the EREV (series hybrid) drivetrain. This would likely be needed to ensure that the EREV helps Stellantis meet their overall CAFE requirements. I understand that they're having relability problems with the resulting engine. I'll be interested to see if Stellantis gets the Atkinson-cycle Pentastar working reliably for the 2026 model year, or if they'll just throw in the towel and do what is probably a small amount of engineering to use the current production Pentastar (since there is no longer any financial penalty for failing to hit the CAFE targets).

 

[sotek2345]

The BEV Lightning lacks some of these key wish-list features: you can't readily tow a max-size camper trailer 600 miles to a wilderness campsite; you can't do a coast-to-coast cannonball run; you can't take a weekend roadtrip on a whim and without a plan. The fact that most people don't do these things doesn't really matter -- people are buying the dream ("well, I could if I wanted to"), not the reality of actually doing it.

Sorry - have to disagree, we have taken unplanned weekend road trips many times. That said, it is likely location dependent. The Northeast is pretty good for charging infrastructure.

 

[hturnerfamily]

agreed, we jump in either our LIGHTNING SR or our EV9 SR, both with the EPA 'average' 240 mile range, and go anywhere we want, any time we want... we don't have to 'plan'...-that is so 'old school' for EVs... : )

true, though, the charging infrastructure has matured and grown to the point that this is rarely an issue.

on another note, I just the other weekend towed a 7,300 lb camper 202 miles with my SR Lightning... yes, stopping several times to charge, but having no issues 'getting' where I was going, and NONE of it was in any major cities or metro areas... all rural.
Adairsville, Summerville, Scottsboro... not the 'top of the heap' when it comes to thoughts of travel and DC Fast Charging... but, it is.

brought another 4,200 lb camper back the exact same 202 mile route, 12 hours later, with, again, no travel or charging issues, even in the middle of the night...

I digress. It's possible, and easy, if you really want to.

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