EREV - A Horsepower Math Problem?

[carys98]

How so?

I think people will find that they will cause more problems than they solve. Any time people save on the occasional road trip will be more than lost by the additional time they will spend on maintenance and going to the gas station. They will almost certainly be less reliable since they include all of the unreliable parts in a pure BEV with the addition of all the unreliable parts of a gas engine and a generator. If you tow constantly you really need a diesel SuperDuty and if you tow occasionally or never you need a BEV. The narrow slice of the population between those two is the only market where the EREV makes sense. The real solution to move them to BEV is faster charging and more infrastructure.

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[hturnerfamily]

so, for those new to the EREV variation, here are some details:

- the generator ENGINE's output is only to provide electrical charging, thru a converter, to the truck's HV Battery Pack
- the truck's HV Battery Pack is the only power that is attached to the MOTORS between each wheel set, as on the current LIGHTNING

so, there will never be any way to 'continue' driving if the HV Battery Pack is depleted, no matter if the generator ENGINE still has power, or fuel - the HV Battery Pack HAS to be charged in order to provide output.
Now, it may seem clear that if the generator ENGINE has power, and fuel, and is providing output, then the HV Battery Pack will be charging, and the truck can then move....but...

the generator ENGINE will NOT have enough power output, on it's on, the maintain the SPEED and HP/TORQUE to move the truck for 'normal' travel... although, it may be enough to 'turtle mode' in slow motion. There just will not be enough KWH output from the generator ENGINE to the Battery Pack, and in a fast-enough charging speed, to keep up with the truck's motion, under normal conditions, much less under STRESS, such as towing, or terrain.

If you look at the 'Range Extender' generator ENGINE, you are essentially allowing that slower power output to help SLOW the usage of the HV Battery Pack during driving - it is NOT going to REPLACE the same amount of power that the truck is currently using, while driving.

For instance, if you have a 'range' of 200 miles, on HV Battery alone, the generator ENGINE, at FULL OUTPUT, during that WHOLE 200 miles, might render an additional 100 miles... meaning that the generator ENGINE is therefore providing a replacement of only 1/2 of the same power...

if your LIGHTNING EV currently averages about 2mi/kWh, while traveling at an average of 60mph, then you are using 50kwh of your battery pack over 120 miles, over two hours of driving.
This equates to needing a recharging speed of 25kw per hour, or a 240v @ 48amps... probably not very realistic for any portable generator ENGINE... but if it can create a constant 240v @ 24amps, you might be able to replace 1/2 of the used power... extending your miles by 50%, or to 180 miles over the same loss of HV Battery Pack power.

now, this is all also assuming you have a large enough GAS TANK for the generator ENGINE to run constantly this whole time... hmmmm.

 

[MrH42]

It's absolutely painful to read some of these posts. A large portion of you have no idea how these work.

 

[The Weatherman]

Ford already fits a 3.5L twin turbo ecoboost or a 5.0L V8 under the hood. Remove the frunk to go back to a standard setup in the front of the truck and put the generator bit in the transmission tunnel and everything fits nice and neat. Shrinking the battery pack would also free up some room.

Don’t think will work as easily as you think. There is a pretty large electric motor and associated electronics sitting in the space below the drunk floor. If the ERev is only coming in rear wheel drive, then is would work as you describe.

 

[The Weatherman]

I think people will find that they will cause more problems than they solve. Any time people save on the occasional road trip will be more than lost by the additional time they will spend on maintenance and going to the gas station. They will almost certainly be less reliable since they include all of the unreliable parts in a pure BEV with the addition of all the unreliable parts of a gas engine and a generator. If you tow constantly you really need a diesel SuperDuty and if you tow occasionally or never you need a BEV. The narrow slice of the population between those two is the only market where the EREV makes sense. The real solution to move them to BEV is faster charging and more infrastructure.

If I felt like I needed the extended range for road tripping and the occasional towing trip, I would jump on something like this so I could remove it when not needed.

 

[The Weatherman]

so, for those new to the EREV variation, here are some details:

- the generator ENGINE's output is only to provide electrical charging, thru a converter, to the truck's HV Battery Pack
- the truck's HV Battery Pack is the only power that is attached to the MOTORS between each wheel set, as on the current LIGHTNING

so, there will never be any way to 'continue' driving if the HV Battery Pack is depleted, no matter if the generator ENGINE still has power, or fuel - the HV Battery Pack HAS to be charged in order to provide output.
Now, it may seem clear that if the generator ENGINE has power, and fuel, and is providing output, then the HV Battery Pack will be charging, and the truck can then move....but...

the generator ENGINE will NOT have enough power output, on it's on, the maintain the SPEED and HP/TORQUE to move the truck for 'normal' travel... although, it may be enough to 'turtle mode' in slow motion. There just will not be enough KWH output from the generator ENGINE to the Battery Pack, and in a fast-enough charging speed, to keep up with the truck's motion, under normal conditions, much less under STRESS, such as towing, or terrain.

If you look at the 'Range Extender' generator ENGINE, you are essentially allowing that slower power output to help SLOW the usage of the HV Battery Pack during driving - it is NOT going to REPLACE the same amount of power that the truck is currently using, while driving.

For instance, if you have a 'range' of 200 miles, on HV Battery alone, the generator ENGINE, at FULL OUTPUT, during that WHOLE 200 miles, might render an additional 100 miles... meaning that the generator ENGINE is therefore providing a replacement of only 1/2 of the same power...

if your LIGHTNING EV currently averages about 2mi/kWh, while traveling at an average of 60mph, then you are using 50kwh of your battery pack over 120 miles, over two hours of driving.
This equates to needing a recharging speed of 25kw per hour, or a 240v @ 48amps... probably not very realistic for any portable generator ENGINE... but if it can create a constant 240v @ 24amps, you might be able to replace 1/2 of the used power... extending your miles by 50%, or to 180 miles over the same loss of HV Battery Pack power.

now, this is all also assuming you have a large enough GAS TANK for the generator ENGINE to run constantly this whole time... hmmmm.

Thanks for your explanation.

I think you hit it right on the mark and folks should be able to understand the issue and solutions and their limitations.

 

[Albern]

Reading this thread makes it feel like 2010 all over again.

 

[Quibbs]

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.

Wouldn't the entire case for the range extender (ice generator) be to put power back into the batteries? When would you use the range extender? not on your daily commute. You'll go home and charge there.
But when you are towing and need more range. That's the selling point right?

 

[Quibbs]

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

That is not what my statement meant. It meant it will not power the trucks wheels directly. The sole purpose as reported by the Ford rep on this board is to add extra range to the batteries via being a range extending generator.

 

[Deleted member 21405]

It's absolutely painful to read some of these posts. A large portion of you have no idea how these work.

Amen to that! Super painful to read

 

[MrH42]

Some have commented on how the ICE is connected to the wheels ... my discussion of HP math is independent of how ICE and / or the EV battery are connected to the wheels. The horsepower required to power the vehicle towing a trailer is the same (with some minor differences in efficiency) whether the HP is delivered via electrical or mechanical means.

Here is another way of looking at my original point ...

Brian, not AI, from Ford's announcement states ... " That is why our next-generation F-150 Lightning will be an EREV. 100% electric power delivery, sub-5-second acceleration – and adds an estimated 700+ mile range with locomotive-like towing capability."

Let's focus on the 700+ mile range and the locomotive-like towing capability. I will assume that the range of the EREV pulling a heavy trailer is about 350 miles (similar to the 150 mile range with our BEV's 300 mile range extended range HV batteries). If the EREV had the same extended range 131 kWh HV battery, you could assume that the HV battery alone would provide 150 miles of the 350 mile trailer-towing range assumed for the 700+ mile EREV. That leaves 200 miles of trailer-towing range which must be provided by the ICE component of the EREV.

Alternatively, there may be a constant sharing of power between the HV battery and the ICE. Say, it is a 50:50 sharing. Then the HV battery would contribute to 300 miles of trailer-towing range with a 50% total power contribution (which is close to the assumed 350 mile EREV trailer range). The other half of the power would have to come from the ICE. It would take about 175 HP to match the power of the HV battery over the same time period. With efficiency losses, we are looking again at about 200 HP for the ICE.

For this example, the EREV would require a 131 kWh extended range battery pack and a 200 HP ICE to tow a heavy trailer for 300 miles (which is still less than the assumed 350 mile target). So, in essence, you have our current BEV ER trucks plus at least a 200 HP ICE. And, a smaller battery pack would require a greater HP ICE.

The EREV is looking like an F-150 with a 2.7 liter V-6 325 HP EcoBoost ICE (or slightly smaller new engine) with about a 100 kWh battery pack ... or, a plug-in Hybrid truck with electric motor final drive to the wheels. If so, it is the worst of both worlds with doubled up complexity and reliability issues. And, we are all too familiar with Ford reliability issues. It does not add up for me.

It does not add up for you because none of this math or your assumptions make any sense.

You’re all over the place. You’re conflating peak power and average power over time. You’re trying to determine range by talking about power. That’s not how any of this works.

 

[MrH42]

so, for those new to the EREV variation, here are some details:

- the generator ENGINE's output is only to provide electrical charging, thru a converter, to the truck's HV Battery Pack
- the truck's HV Battery Pack is the only power that is attached to the MOTORS between each wheel set, as on the current LIGHTNING

so, there will never be any way to 'continue' driving if the HV Battery Pack is depleted, no matter if the generator ENGINE still has power, or fuel - the HV Battery Pack HAS to be charged in order to provide output.
Now, it may seem clear that if the generator ENGINE has power, and fuel, and is providing output, then the HV Battery Pack will be charging, and the truck can then move....but...

the generator ENGINE will NOT have enough power output, on it's on, the maintain the SPEED and HP/TORQUE to move the truck for 'normal' travel... although, it may be enough to 'turtle mode' in slow motion. There just will not be enough KWH output from the generator ENGINE to the Battery Pack, and in a fast-enough charging speed, to keep up with the truck's motion, under normal conditions, much less under STRESS, such as towing, or terrain.

If you look at the 'Range Extender' generator ENGINE, you are essentially allowing that slower power output to help SLOW the usage of the HV Battery Pack during driving - it is NOT going to REPLACE the same amount of power that the truck is currently using, while driving.

For instance, if you have a 'range' of 200 miles, on HV Battery alone, the generator ENGINE, at FULL OUTPUT, during that WHOLE 200 miles, might render an additional 100 miles... meaning that the generator ENGINE is therefore providing a replacement of only 1/2 of the same power...

if your LIGHTNING EV currently averages about 2mi/kWh, while traveling at an average of 60mph, then you are using 50kwh of your battery pack over 120 miles, over two hours of driving.
This equates to needing a recharging speed of 25kw per hour, or a 240v @ 48amps... probably not very realistic for any portable generator ENGINE... but if it can create a constant 240v @ 24amps, you might be able to replace 1/2 of the used power... extending your miles by 50%, or to 180 miles over the same loss of HV Battery Pack power.

now, this is all also assuming you have a large enough GAS TANK for the generator ENGINE to run constantly this whole time... hmmmm.

This math and assumptions in this are all wrong.

You’re confusing peak power output vs average output.

Let's start with some of these assumptions:

It's not designed to drain the battery down to zero and then start the range extender. That doesn't make any sense. The range extender will likely be an atkinson cycle 4 cylinder, maybe 6 cylinder engine. The default way for it to run would be at a set RPM for maximum efficiency. There will probably also be a max power engine parameter to run as well.

There will be an algorithm that looks at remaining battery range, and expected loads and determine when to kick on the range extender. Something like: when you're just driving around, when the battery gets to 20% remaining, the range extender kicks on in efficiency mode to try to maintain the charge between 20-40%. You can still extract all the power that you would when it's not on! This is designed so it doesn't ever have to go into "turtle" mode.

If you're towing something, the vehicle would see the increase power demand and maybe kick on the range extender at 40% instead. If it sees sustained load for a long time (ie. you're towing up a mountain or something), maybe it operates the range extender at max output as opposed to max efficiency.

Either way, the range extender is going to attempt to estimate future power demand and kick on when needed in various operating modes to maintain a minimum base level in the batterie so that you get full power (or at least very very close to full power) at all times.


Let's take your hypothetical example.

If you average 2 mi/kWh, , you're traveling 60 mph, and you travel 120 miles, you're consuming 60 kWh of the battery in the course of 2 hours. That's a power draw of 30 kW on average.

There's no need to talk about voltage or amperage. kW is a measure of power. The atkinson 4 cylinder in the Ford Maverick makes 162 horsepower. That's 119 kW. That's likely peak power. There are some efficiency loss in converting it for the battery too (say 10%? Not sure if that's right, but let's use it as a placeholder). It's more than plenty to maintain a 30 kW draw from the battery. Let's say you're towing: again, if you average 1.0 mi/kWh in a Lightning towing a heavy load, you could easily output that with the Maverick motor.

The batteries act as a buffer to allow for huge power demand. The generator just needs to keep up with the average power consumption, not the peak.

 

[Lytning]

Ya'll need to stop throwing HP and KW together in this thread it just makes it confusing jumping back and forth and that they dont really represent the same idea in this construct.

The Lightning stores kwh, and uses kw while driving.
2.0mi/kwh at 70mph is 35kw average, meaning you use 35kwh in one hour. To maintain even steven you need a generator to output 35kw continuously.

Assuming you are pulling a trailer and getting 1.0mi/kwh you need a generator capable of 70kw.

The question is if Ford will engineer for zero average battery depletion in a worse case situation, or allow allow battery SOC to drop while driving (you can bet they will, they have to).

My estimate, ~70kw. Steady state towing a modestly sized RV or a heavy but small trailer. Doing that in the mountains will depleate your battery.

Battery will be 70-90 kw, just below SR now, saving battery. This marches the performance figure.

Agreed. My inaccurate post has been deleted to prevent further confusion. Your analysis is much better.

Where HP and KW do intersect is in what size ICE is required to drive the generator. It would take about a 100 HP ICE to drive a 70 KW generator.

 

[astrand1]

This math and assumptions in this are all wrong.

You’re confusing peak power output vs average output.

Let's start with some of these assumptions:

It's not designed to drain the battery down to zero and then start the range extender. That doesn't make any sense. The range extender will likely be an atkinson cycle 4 cylinder, maybe 6 cylinder engine. The default way for it to run would be at a set RPM for maximum efficiency. There will probably also be a max power engine parameter to run as well.

There will be an algorithm that looks at remaining battery range, and expected loads and determine when to kick on the range extender. Something like: when you're just driving around, when the battery gets to 20% remaining, the range extender kicks on in efficiency mode to try to maintain the charge between 20-40%. You can still extract all the power that you would when it's not on! This is designed so it doesn't ever have to go into "turtle" mode.

If you're towing something, the vehicle would see the increase power demand and maybe kick on the range extender at 40% instead. If it sees sustained load for a long time (ie. you're towing up a mountain or something), maybe it operates the range extender at max output as opposed to max efficiency.

Either way, the range extender is going to attempt to estimate future power demand and kick on when needed in various operating modes to maintain a minimum base level in the batterie so that you get full power (or at least very very close to full power) at all times.


Let's take your hypothetical example.

If you average 2 mi/kWh, , you're traveling 60 mph, and you travel 120 miles, you're consuming 60 kWh of the battery in the course of 2 hours. That's a power draw of 30 kW on average.

There's no need to talk about voltage or amperage. kW is a measure of power. The atkinson 4 cylinder in the Ford Maverick makes 162 horsepower. That's 119 kW. That's likely peak power. There are some efficiency loss in converting it for the battery too (say 10%? Not sure if that's right, but let's use it as a placeholder). It's more than plenty to maintain a 30 kW draw from the battery. Let's say you're towing: again, if you average 1.0 mi/kWh in a Lightning towing a heavy load, you could easily output that with the Maverick motor.

The batteries act as a buffer to allow for huge power demand. The generator just needs to keep up with the average power consumption, not the peak.

It’s quite possible that they will utilize the gps/nav to help the pcm decide usage of the range extender. That technology has already been in use for a few years in the heavy truck (class 8) world. The pcm (engine computer) uses gps data so that it knows where the truck is at all times as well as the engine load to help determine trans gearing etc. to try to stay in the most efficient gear and rpm range. I could easily see ford using a similar technology to help the range extender predict possible usage.

 

[Scorpio3d]

I believe Ford even mentioned a locomotive in their release for those still confused maybe this helps or maybe it will confuse you more!

A diesel locomotive operates by converting diesel fuel into mechanical energy through a diesel engine, which powers electric generators that drive traction motors to move the train.

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