EREV - A Horsepower Math Problem?

[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.

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[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.

 

[MrH42]

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.

Yeah, good point.

This is the exact kind of reason why GM is trying to push everyone to use the in-car navigation as opposed to something like CarPlay. Even though they would need to pry CarPlay from my cold dead hands, I totally get why they're pushing in that direction

 

[astrand1]

Yeah, good point.

This is the exact kind of reason why GM is trying to push everyone to use the in-car navigation as opposed to something like CarPlay. Even though they would need to pry CarPlay from my cold dead hands, I totally get why they're pushing in that direction

Same for me. You ain’t taking my CarPlay away! lol. Even still with map integration they CarPlay or the oem gps the truck still “knows” where it is at any given time so it’s a possibility. Will be interesting to see how it plays out. But as with CarPlay at this point you’d have to also pry my lightning out of my cold dead hands as well!

 

[Quibbs]

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.

Mr.Magoo is correct and I thought that my wording was clear enough that most folks would get what I was saying.

I was replying to the op of the thread.

He seemed inclined to believe the generator would also function as a standard motor as well, driving the vehicle itself as opposed to powering the batteries. At least that was my interpretation.
Of course it would be connected to the batteries, which are part of the power train in that regard.

 

[reddog21]

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

If you know exactly how they work, then share it with the rest of us. Last I checked, Ford hadn’t made any specific announcements, so how can anyone be right or wrong?

If I said it’s going to be diesel and not gas, I’m neither right nor wrong since no announcement has been made. It’s an exaggeration, but who knows—car manufacturers do stupid things all the time..

I'm looking at it like it's going to be pretty close to the Ram charger unless I can find specific information otherwise.

 

[reddog21]

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?

Not necessarily—the generator’s role would be to maintain, not charge. In theory, if there’s no load, it could charge the battery, but I’d guess it would take quite a while to do so and is it necessary.

 

[PJnc284]

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.

Farley also said that people would be able to drive on battery 90% of the time which would seem to indicate it won't be running 100% of the time but who knows. Everything at this point is just speculation.

 

[hturnerfamily]

it's obvious that no matter how you do the 'math', whether you use khw or HP or peak or any other nomenclature, there is no generator ENGINE that is going to, on it's own, provide enough output to power the vehicle at 60mph, and charge/replenish the battery pack at that same rate... otherwise, it would just be an Engine, just like every other gas vehicle.

the 'range extender' idea is to EXTEND battery pack power/range, not to REPLACE it... therefore, it stands to reason, that no matter how LONG you run the generator ENGINE, even from the moment you leave your garage, it will not REPLACE the amount of power you are using to move the vehicle down the road... but, it is only 'adding' some kw of power during that time, to help 'extend' your ultimate range, otherwise.

It's no different that the magical and recent videos of putting a high-power generator in the bed, and feeding that output to the battery pack - that generator will never be able to power the truck, on a 1 to 1 basis... but it is simply helping to calm range anxiety for some... it is also going to take a LOT of fuel along the way...

my point is that this design is not a pie-in-the-sky answer, not in REALITY, as some might be assuming... it may be more of a 'run the generator all the time' for long-range travel, versus what some may be thinking: 'just turn it on when we need it'... it may then be too late.

 

[PJnc284]

It's no different that the magical and recent videos of putting a high-power generator in the bed, and feeding that output to the battery pack - that generator will never be able to power the truck, on a 1 to 1 basis... but it is simply helping to calm range anxiety for some... it is also going to take a LOT of fuel along the way...

I'm still skeptical on the benefit towing especially if you're 1mi/kWh or worse but it could significantly increase non-towing highway range even at 48 amps and the cost/kWh added is on par with dcfc membership rates (at current gas prices anyway). Curious what it sounds like going full out when someone drives up next to it. I suspect the cost will end up being a turnoff for most though.

 

[hturnerfamily]

here's a terrific explanation video of the upcoming RAM EREV, which will have the similar configuration of the LIGHTNING EREV... watch the whole video, as he is great at giving us real-world operational info...

 

[Dan C]

The real math problem is the affordability. I dont see a great price reduction in this model. I do see a frunk reduction

 

[pirate4x4lance]

I'm curious... They say the truck will have a "700 mile range"... So What if you're doing a 1500 mile road trip? Will the battery be depleted after 700 miles, AND the gas tank is empty as well, meaning you need to go to a gas station AND a DCFC? Or will the truck be able to play "catch up" and recharge itself to a stable point once you refuel with gas and continue on your road trip.

 

[PJnc284]

Methinks you'll need to find a charger before you hit 0 and then go get gas. Also I bet that "700 miles" will be at lower speeds and not 70mph+

 

[RdWarriorRuss]

EREV is not a new concept. Train locomotives have used this basic design for 75+ years. The potential problem here is that most people don’t tow every day and most people don’t road trip every day. The genset won’t run as much as it should and the gas will get sour in a lot of vehicles. Engines that sit idle all the time tend to break down. That’s why whole home generators should be cycled once a week. I don’t worry about battery longevity in EVs but I would definitely worry about engine longevity in a higher mileage EREV. What would that do to depreciation going forward? There are a lot of engineering challenges here to contemplate. The solution would be to run the engine all the time and basically trickle charge the battery. If that’s the case, why not just buy an ICE truck and avoid the potential pitfalls?

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