Harvester Directly Powering Motors?

[Paddywhack]

To start with, I know the harvester isn't going to be mechanically attached to the motors. I want to clarify that's not what I'm asking about.

I watched a couple videos on diesel electric trains recently and noticed that some designs have their diesel engine directly connected (electrically) with the train's electric motors and provide power that way. The train does still have batteries but they don't drive the motors primarily.

From what I've seen with the harvester it's always in reference to charging the batteries to add range to the vehicle. If you're charging the battery to immediately drive the motors wouldn't that create additional wear and tear on the battery?

Provided that the harvester is going to be beefy enough to power to the motors wouldn't "directly" powering them and then having the excess energy go to charging the battery be better? I'm not sure if this is something SM is planning to do already.

 

[DaveGunter]

To start with, I know the harvester isn't going to be mechanically attached to the motors. I want to clarify that's not what I'm asking about.

I watched a couple videos on diesel electric trains recently and noticed that some designs have their diesel engine directly connected (electrically) with the train's electric motors and provide power that way. The train does still have batteries but they don't drive the motors primarily.

From what I've seen with the harvester it's always in reference to charging the batteries to add range to the vehicle. If you're charging the battery to immediately drive the motors wouldn't that create additional wear and tear on the battery?

Provided that the harvester is going to be beefy enough to power to the motors wouldn't "directly" powering them and then having the excess energy go to charging the battery be better? I'm not sure if this is something SM is planning to do already.

This has been talked about on the forum a bit, there are some posts in this thread. Go to page 10.

https://scoutmotors.community.forum/threads/speculation-alert-possible-harvester-engine-choices.1085/

It would be technically more complicated to have the generator supply electricity to the drive motors directly, but it would as you point out put less stress on the batteries, it would also be more efficient as it would avoid two phase changes as well. There are efficiency losses with every phase change.

GM (Volt), BMW (I3), and Nissan (ePower) had the generator supply the drive motors directly, and it appears as though Ram (Ramcharger) will as well. The Volt also had a mechanical connection to the wheels.

Scout in there presentations and literature have said that the Harvester will only charge the battery.

Some believe Scout verbatim and think that Scout will only have the generator charge the battery.

Some believe Scout are just keeping the message simple and emphasizing the EV operation of the vehicle and that Scout will have the Harvester supply electricity directly to the drive motors. The inverter will act as a "router", the electricity from the Harvester will be routed to the drive motors preferentially, and based on the instantaneous demand of the drive motors, any excess will be inverted and stored in the battery, any deficit will be supplied by energy already stored in the battery.

I'm inclined to believe the second group.

 

[J Alynn]

While two years is a long way away I will add it was stated during the reveal (in a conversation-not official press) that the extender will ONLY power/charge the battery. Can/will that change-maybe! But as of today the intent is battery charging only. I’m not mad at anyone as it’s fun to speculate on many things on this forum-we’ve done it for two years now. Even after the physical vehicle launch we are still speculating. That said, I personally think this subject should be put on hold until SM announces and defines the final engine/generator/fuel mix and proper wiper fluid to run the Harvester as they intend to have it run. One LONG running thread of this was plenty.
But again, unofficially told at the reveal the range extender is direct to battery-not to motors or any other area.
Maybe we need another color poll or a bit of new “something” so we can speculate over something other than the exact specifics of the extender.

 

[CarTechGeek]

To start with, I know the harvester isn't going to be mechanically attached to the motors. I want to clarify that's not what I'm asking about.

I watched a couple videos on diesel electric trains recently and noticed that some designs have their diesel engine directly connected (electrically) with the train's electric motors and provide power that way. The train does still have batteries but they don't drive the motors primarily.

From what I've seen with the harvester it's always in reference to charging the batteries to add range to the vehicle. If you're charging the battery to immediately drive the motors wouldn't that create additional wear and tear on the battery?

Provided that the harvester is going to be beefy enough to power to the motors wouldn't "directly" powering them and then having the excess energy go to charging the battery be better? I'm not sure if this is something SM is planning to do already.

You are correct, it make sense to bypass the battery and go directly to the motors whenever possible.

That presentation by Scout was in "marketing speak". IOW dumbing it down for the masses.

I 100% guarantee that in many situations, Generator power will flow directly to Inverter (which is shorthand for inverter and all other power control electronics), from the inverter, directly to the wheel motors, bypassing the battery.

Everything is will be precisely controlled by the inverter. All the power has to go through the inverter to be conditioned, AC->DC and DC->AC conversion are done, and Voltage/current/Frequency is appropriately set.

The generator will be outputting AC, the motors run AC, the Batteries are DC.

Even if you could charge a battery simultaneously while remove more power from it than you are putting in (which you can't), you have to consider the waste of extra steps that charging first would require:

A: Generator (AC)->Inverter (convert to DC) > Battery (Charging DC) ...
... Battery (Discharging DC) > Inverter (convert to AC + adjust AC frequency) > Motor (AC).

Is MUCH less efficient than.

B: Generator (AC)->Inverter (adjust AC frequency) > Motor (AC).

No one in their right mind is doing A: when B: is possibly because B: is much more efficient.

A: doesn't even make sense except as separate steps. At any moment in time you can only charge or (exclusive or) discharge a battery. You can't do both at the same time.

 

[Paddywhack]

Thanks everyone for the input! I didn't have much luck looking for this info myself and only got through about page 3 of the thread that DaveGunter linked on my own lol.

I definitely agree that this is something to table until we have more info from SM but was curious about the current situation.

 

[R1TVT]

I 100% guarantee that in many situations, Generator power will flow directly to Inverter (which is shorthand for inverter and all other power control electronics), from the inverter, directly to the wheel motors, bypassing the battery.

I have questions.... How can you 100% guarantee anything when we have ZERO Harvester or battery details disclosed by Scout?

No one in their right mind is doing A: when B: is possibly because B: is much more efficient.

You keep alluding to inefficiency, but ignore the physics of propelling a relatively inefficient 7000+ Pound, block of a truck truck (not a small car) up a mountain or down a HWY with what is likely to be a small-output / low HP gas generator engine?

At any moment in time you can only charge or (exclusive or) discharge a battery. You can't do both at the same time.

Since EV batteries can be separated into modules, if I were designing a new battery pack for the Scout with the Harvester option, I would potentially consider enabling a module-based charging system to isolate parts of the battery for charging, while discharging from separate modules. Is that possible? I don't see why such a system couldn't be engineered, since modules can be logically and physically segregated by design, and you could seemingly "roll-charge" from module-to-module as power is discharged from groups of isolated modules that are ONLY consuming energy (and not charging at the same time).

Could switching seamlessly between partitioned battery modules for charge and discharge be one of the secrets to Scout's EREV Harvester design? I don't know, but I will give Scout leeway and the benefit of the doubt, and not assume that I am 100% correct about how the Harvester will be implemented.

Again, I have no dog in this fight, as I am only interested in the Pure EV with 350 miles of range!

 

[CarTechGeek]

I have questions.... How can you 100% guarantee anything when we have ZERO Harvester or battery details disclosed by Scout?

Because I understand how the technology works. No PHEV or EREV uses the Generator to "only" charge the battery because it makes no sense from a engineering perspective. But many if not most say that in marketing materials. Marketing and Engineering are different things, and they can often contradict. You look at the marketing if you want a superficial comparison to competitors, but you don't actually care about the details of how it actually works. If you want to understand in detail how something actually works, you need to largely ignore the marketing and look at the engineering.

You keep alluding to inefficiency, but ignore the physics of propelling a relatively inefficient 7000+ Pound, block of a truck truck (not a small car) up a mountain or down a HWY with what is likely to be a small-output / low HP gas generator engine?

I'm not ignoring anything. Using the Generator to Only charge the battery, would waste about 10% of the energy on pointless extra energy conversions. So Instead of getting about 20 MPG running on the Harvester, you would get about 18 MPG. That might not seem like a lot to you, but it is a lot the engineers.

Could switching seamlessly between partitioned battery modules for charge and discharge be one of the secrets to Scout's EREV Harvester design? I don't know, but I will give Scout leeway and the benefit of the doubt, and not assume that I am 100% correct about how the Harvester will be implemented.

Theoretically you could do that. But why would you?

• It's less efficient.
• It's more wear and tear on the battery.
• Less output for things like climbing hills.

It's lose-lose-lose. All disadvantages, no advantages. Unless you think having engineering dictated by dumbed down marketing messages, is an advantage.

I've posted the Nissan explanation before, because they do a better job than most, but what I didn't post is Nissans contradictions in their explanation. I'll do that in another post, because I don't want to make this one super long.

 

[J Alynn]

This seems a bit heated!
I would add, beyond the fact that I also have no dog in the fight as I’m going full EV. A number of us were at the reveal and spoke to a lot of folks-kinda a Vegas approach if you get my point. Needless to say, realizing things can change, it was mentioned multiple times to a bunch of us at the event that the generator will only feed the battery.
If it was up to me I’d close this discussion thread all together. There is a lot of speculation and seemly more hostility around this subject.
Whether or not any of us are experts or not on this relatively new technology we are not privy to the engineer’s meeting notes and thus far, the only consistent message is “power to battery only”
Perhaps @CarTechGeek works for SM and we don’t know it. Or perhaps he knows the industry as stated but short of knowing SM’s plans nobody actually knows so rather than assuming you know the answers we’d all be best to let this thread die!

 

[CarTechGeek]

From the Nissan explanation of how E-Power works.

e-POWER system | Innovation | Nissan Motor Corporation Global Website

Nissan’s e-POWER system: Nissan’s various technologies, including electrification, autonomous drive, connected car & service, mobility service, and energy management, are introduced.

www.nissan-global.com

Since the engine connected to the generator only charges the battery and does not directly drive the wheels, it is possible to freely set the start timing and efficient RPM.

Sounds familiar, and clear cut. The generator only charges the battery. The very next sentence though offers some contradiction.

Generated electricity charges the high-voltage battery and directly drives the motor.

You might argue that the language is imprecise enough to mean, "charges the battery, and the battery directly drives the motor.", but that's not it. Check out the "high speed" portion of this image, and the text: "Driven by generated power while also charging the battery".

The are clearly sending generated power directly to the motor, while some left over amount is also sent to do battery charging. The battery is NOT sending power to the motor.

Still Not convinced?

Here is a one of the Lead Nissan Engineers (not Executive with an MBA) explaining how it works:

Here is an important excerpt, but by all means read the full page and what the full video:

... engine that generates electricity. That electricity moves to an inverter and then the brain of the vehicle will decide where that electricity goes from there, so the inverter can send it as DC current to the battery or it can send it as AC current to the drive motor, to drive the wheels or both at the same time ...

All of Nissans more detail explanations, contradict their more marketing oriented statement that the "generator only charges the battery". That statement is widely used by multiple companies, to hammer home that this is more like an EV, drives like an EV, the Gas Engine doesn't drive the wheels, but should be taken as literal engineering detail of how it works.

Read the Nissan page, watch the Engineers video, if you want to better understand how this works, but don't take a marketing statement to be factual detail about how an engineering process works.

 

[J Alynn]

Fair but Nissan is currently looking to Honda as a last ditch effort to not declare bankruptcy so while there might be merit they certainly aren’t doing enough things right currently.
I’m just gonna wait until SM tells us how it’s going to work rather than the speculation on this thread

 

[CarTechGeek]

The main point is that Nissan has that same marketing message, but also has more engineering details showing how it's actually done (and the contradictions between them).

I do not work for SM, but I do have enough background to know that the way Nissan handles it makes sense (though E-Power could gain more highway efficiency, by clutching in a physical connection), and a Generator literally doing "charging only" does not really make sense from an engineering perspective.

The problem is right now we only have marketing info and people are treating it like Engineering fact.

 

[LastDayScout]

The Harvester and Administration threads both need to be flushed. The Harvester one can come back once we have some official info from Scout. My unempowered, unofficial, personal opinion.

 

[R1TVT]

The problem is right now we only have marketing info and people are treating it like Engineering fact.

To be clear, that is not what I was saying (if you were directing that to me). In fact, I have quite clearly stated that we require engineering facts before we can accurately assess and comment on the Harvester implementation. You, on the other hand, assume that Scout must implement its Harvester configuration the way it has been done in other Hybrid cars (not trucks). Nobody here is disputing what has already been done in cars - seriously - you are not the only one on the forum that knows how inverters and hybrids work (and have already been implemented).

For me, the debate is if Scout's implementation might or could be different, based on what was stated AND based on the small space we saw reserved for the Harvester (which was NOT in the engine compartment, as in your Nissan example). This certainly doesn't look like what we saw at the reveal. This looks like a gas engine connected to a generator sitting between 2 front wheels in a traditional engine compartment to me. This 1.2L Nissan E-POWER gas engine & generator combo would DELETE the frunk:

 

[LastDayScout]

I haven't said it yet, but I think it is time now. I lifted the cargo floor of the Traveler when the security guards were not looking. The pictures attached are what I saw. I think they are sandbagging the estimated range.

 

[J Alynn]

I haven't said it yet, but I think it is time now. I lifted the cargo floor of the Traveler when the security guards were not looking. The pictures attached are what I saw. I think they are sandbagging the estimated range.
View attachment 4376View attachment 4377

Holy shit. I’m still wiping tears from my eyes

 

[CarTechGeek]

To be clear, that is not what I was saying (if you were directing that to me). In fact, I have quite clearly stated that we require engineering facts before we can accurately assess and comment on the Harvester implementation. You, on the other hand, assume that Scout must implement its Harvester configuration the way it has been done in other Hybrid cars (not trucks). Nobody here is disputing what has already been done in cars - seriously - you are not the only one on the forum that knows how inverters and hybrids work (and have already been implemented).

I'm not the only one, but I'm certainly in the minority, so I'm offering additional info, so more people can better understand how Series Hybrid designs work. Most people seem to be still assuming that the generator will only charge the batteries because that was what the SM marketing says.

The Nissan example is a very good that highlights how marketing and engineering contradict each other, and explains in greater engineering detail how it actually works.

Yes, I'm assuming that Scout has capable engineers that wouldn't make, such a ridiculous mistake and build an EREV, where the generator can "only charge the batteries". It's a very reasonable assumption because it's hard to imagine they would hire one engineer capable that kind of fundamental mistake, let alone a whole team of them.

This certainly doesn't look like what we saw at the reveal. This looks like a gas engine connected to a generator sitting between 2 front wheels in a traditional engine compartment to me. This 1.2L Nissan E-POWER gas engine & generator combo would DELETE the frunk:

The location of the generator, doesn't change it's fundamental operational principles.

It changes physical packaging, like luggage space, but that wasn't the issue under discussion.

 

[R1TVT]

The location of the generator, doesn't change it's fundamental operational principles.

It changes physical packaging, like luggage space, but that wasn't the issue under discussion.

Totally disagree. Physical packaging & location of the Harvester is entirely part of the equation and absolutely must be a consideration for this discussion. Alluding to technology that exists today (in a full sized engine compartment) and not accounting for the fact that the Scout is not a car, but a truck, and that the Scout will have a FULL FRUNK are clearly at odds with each other. There must be some innovation around this implementation.

BTW, I am not saying you're wrong in pointing to existing technology, or to examples of other series hybrid implementations to demonstrate how EREV's or series hybrids work. My POV is that the small space for the Harvester, coupled with the fact that Scout has stated that this will be an EV and will have a frunk must necessitate some new technology, or at a minimum a very different configuration than we have seen to date.

Like I said weeks ago on this forum, my uneducated guess (since I do not work at Scout) is that the battery pack for the Scout with the Harvester is likely larger than has been speculated and will have more buffer. I also think Scout will be taking advantage of other battery advancements, but we'll have to wait and see. Of course costs are major factor, but we don't know where costs will be by the time of production either.

 

[Ike]

I haven't said it yet, but I think it is time now. I lifted the cargo floor of the Traveler when the security guards were not looking. The pictures attached are what I saw. I think they are sandbagging the estimated range.
View attachment 4376View attachment 4377

Pretty sure these only deal in time range. You are still in the same "place" when you use them. I really don't want to go back to 1955 every time I get in my scout... That just seems like a hassle.

 

[J Alynn]

Pretty sure these only deal in time range. You are still in the same "place" when you use them. I really don't want to go back to 1955 every time I get in my scout... That just seems like a hassle.

But you could take gold and convert it to old currency and then buy stock in IBM, or the equivalent in 1955. Then when they start making the Scouts you can buy 3-

 

[SpaceEVDriver]

Pretty sure these only deal in time range. You are still in the same "place" when you use them. I really don't want to go back to 1955 every time I get in my scout... That just seems like a hassle.

You only have to worry about the time issue if you go above 88 mph. For most driving, you'll be fine.