You got 30mpg in a 3500HD diesel towing 8K? How the heck did you manage that? I have a couple of friends that have HD diesels (for their horse trailers) and they don't get above 20mpg even without the trailer.
5klbs towing cap with gas range extender?
- Thread starter mattrawls93
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You got 30mpg in a 3500HD diesel towing 8K? How the heck did you manage that? I have a couple of friends that have HD diesels (for their horse trailers) and they don't get above 20mpg even without the trailer.
3500HD Chevy Express with a WWII searchlight behind. No idea how, but the '97, '98 &'99 models all pulled the same mpg with the same 6.5L Duramax. Those vans were pretty much empty shells that only pulled 24mpg unladen, but they consistently pulled 30mpg with the trailer back there, pretty much 100% highway mileage, driven overnight. I'm guessing something about the large round searchlight helped aerodynamics, but each fill up was tracked, gas receipts, etc. I really liked driving those vans for some reason.
Almost identical to this setup, genset up front, carbon-arc light on the back:
Scout themselves have said they are getting the EV Software from Rivian and it's probably getting tweaked some. The Rivian partnership has changed a lot with the development, they even had one of the mules at Rivian.
However the Range Extender software isn't ready. They're still struggling with thermals of the engine in the back but it should be able to be resolved.
However the Range Extender software isn't ready. They're still struggling with thermals of the engine in the back but it should be able to be resolved.
Welcome to the forum. Thanks for posting. As you are new can you clarify where you heard about the thermal issues?
I can't speak for the OP but I recall in one of these threads about the Harvester towing capacity and the Davis Dam test, I made the assumption that the problem was tongue weight due to the location of the engine. Jamie chimed in that passing the Davis Dam test was more about managing thermal loads. I took that as agreeing with the OP that they are limited by thermal management at this point. Still plenty of time and Harvester is playing catch-up as it was designed fairly recently but think about it - in a front-engine vehicle, you get all of that nice fresh air blowing right into the engine and the coolant runs from engine to radiator are short. Getting cool air to a mid or rear mounted engine adds challenges - hence you see a lot of creative scoops (ie NACA ducts: https://en.wikipedia.org/wiki/NACA_duct) and things on mid-engine sportscars and the like.
Update: here's the post from Jamie: https://community.scoutmotors.com/threads/scout-delayed.7517/post-73826
It is the overall thermal management, battery energy density, etc., etc. Let's see where things land in the end.
Thanks Jamie. I meant to add that I was reading between the lines of your post. I also know that the team is doing everything they can to increase the tow rating of the Harvester as that is such a quoted number in the truck world.
Thank you, it's been a long time since the VW Vortex days.
Besides just saying "Internal Sources at Rivian/Scout/Volvo-Polestar" it's just going to be a crazy random posting on a Forum.
Jamie mentioned it's an issue that needs to be tested more which was linked above.
It's been years since the BMW i3 but one of the US software limits to be an EV with the ICE Generator was the Generator was only allowed to be used during certain times once the battery was fully depleted. This affected it's highway speed as the generator couldn't keep up production. That and the Smokey Eunuch style fuel tank Bladder to limit fuel capacity was funny.
I'll take an education guess and say the disconnected from the Drivetrain, modified N/A 4 Cylinder Generator will be the choke point. The Turbocharged Atlas has a 5000lb towing capacity like many other VW SUVs so I'd say the minimum guess rating was to play it safe until they can test the engine once Software for the Vehicle and Engine are available.
Since Rivian & Scout have announced more platform sharing plans and the heavy VW investment is pretty obvious Scout pivoted to Rivian's Zonal Electrical Architecture to save on wiring & reduce modules.
Some leaks from Rivian are the "base map" if you will, is going to be EV only with no engine controls. Since Rivian does EVs only, it's understandable. The ICE Generator is some VW 4 Cylinder from the Generic Patent Images . And one of the head guys at Scout said it was one too
When the Scout Vehicles initially came out the preorders were about even. Then we know it has shifted to SIGNIFICANTLY more for the Extended Range EV.
BUT hey, fuel prices might cause that to shift again!
Discussed in the Podcast was that the Solid Axle, Fuel tank, Battery, and all will basically be interesting to package!
Having been a part of BMW's i8 and i3 Program, it's thermals and insulation are going to be the crux.
Judging by some Glass Door Reviews it and some words from former employees, especially one from Stellantis, there's a lot going on and a lot not going.
It would be a good time to release some Mule Footage and the Winter Testing video was IMPRESSIVE!
Really wanting this to succeed to get rid of my Model Y that Blake knows is just holding me over.
Thank you very much for posting this and providing background. Appreciate the education and not just random thoughts to get everybody wound up over something. Thanks again
I'm amazed that I suck so much at multi-tasking, but I can be working and these random thoughts pop into my head:
If the towing issue is a thermal management issue, I assume that's in the battery/inverter/motor area since the Harvester portion would be unaffected by towing or grade since it's mostly a fixed-RPM generator. With that said, if those EV components are beefed up in some way for towing, would the estimated 0-60mph time of 4.5 seconds also improve since that's likely limited by the battery discharge rate.
If the towing issue is a thermal management issue, I assume that's in the battery/inverter/motor area since the Harvester portion would be unaffected by towing or grade since it's mostly a fixed-RPM generator. With that said, if those EV components are beefed up in some way for towing, would the estimated 0-60mph time of 4.5 seconds also improve since that's likely limited by the battery discharge rate.
I do not believe that 0-60 will be affected. As you said, cell discharge rate affects the 0-60 and that is primarily based on cell chemistry (thermal mgmt only comes into play if you try to make repeated 0-60 or 1/4 mile runs). Thermal management is what is limiting the towing which is carrying heat away from the engine and battery pack. Also, if they are smart (and have torn down a recent model Tesla) they will have inspected Tesla's octo-valve which allows them to move heat from anywhere to anywhere.
But you have got me thinking, which I have done very little of when it comes to hybrids. Will the generator and battery pack use the same coolant or will they be separate? If they use common coolant, then with a fixed amount of heat exchanger (radiator) area, you need to balance the thermal needs of the battery and generator. So when the generator is running you have less cooling for the battery. But if you separate them then even when the generator is not running you cannot use the generator's heat exchangers to cool the battery. It seems to me that using a common system would be best as you could use the full heat exchanger capacity wherever it is needed but engines run way hotter than batteries so Idk if that would even work.
@SpaceEVDriver and I were discussing this a few weeks back, but the Harvester patents show the whole Harvester subassembly as pretty much stand-alone with it's own cooling system as part of the assembly.
I'm curious what they do for a radiator with the location of the Harvester.
We don’t know what Scout is going to do yet.
There are sensible decisions that could be made in either direction: an integrated cooling system or a completely separate, self-contained cooling system.
If it’s integrated with the battery/motors/etc, it’ll probably require diverter valves in key places so the thermal controls of certain parts can be isolated when necessary. If it’s integrated, interesting options become available.
One such option is the warming of the ICE block before it’s even started, either through L2 charge port power input running the heat pump, through battery self-heating, through battery running the heat pump, or through motor self-heating (some brands, including Rivian, can stall their motors to heat them up—think induction cooktop—and then that heat can be distributed to various components via fluid/coolant pumps). This option would mean you could garage your Harvester AND warm up the engine before you head out on a trip—not a safe option to start the combustion of an ICE on vehicles that produce carbon monoxide while heating up. This would greatly improve on-road efficiency, though at the cost of some additional energy before you start driving. Overall I think the energy cost would be lower.
I can think of a dozen other reasons to integrate the thermal management.
If it’s kept separate, removal of the Harvester could be somewhat easier, depending on how things are engineered. But I think it would be a major engineering challenge to include a heat exchanger/radiator within the Harvester cage under the vehicle. Placing an air source heat exchanger directly below the passenger space, under the vehicle where there’s minimal air flow, is fraught with many potential problems. They will almost certainly need to have that be a remote part that needs to be disconnected.
But I’m just making guesses…
I will never trust the images in a patent application. Those aren’t meant to give a competitor the means to reverse engineer the system, they’re meant to give the patent office a visual to sort-of explain what they’re thinking without giving away the details before the thing is even in production.
There are sensible decisions that could be made in either direction: an integrated cooling system or a completely separate, self-contained cooling system.
If it’s integrated with the battery/motors/etc, it’ll probably require diverter valves in key places so the thermal controls of certain parts can be isolated when necessary. If it’s integrated, interesting options become available.
One such option is the warming of the ICE block before it’s even started, either through L2 charge port power input running the heat pump, through battery self-heating, through battery running the heat pump, or through motor self-heating (some brands, including Rivian, can stall their motors to heat them up—think induction cooktop—and then that heat can be distributed to various components via fluid/coolant pumps). This option would mean you could garage your Harvester AND warm up the engine before you head out on a trip—not a safe option to start the combustion of an ICE on vehicles that produce carbon monoxide while heating up. This would greatly improve on-road efficiency, though at the cost of some additional energy before you start driving. Overall I think the energy cost would be lower.
I can think of a dozen other reasons to integrate the thermal management.
If it’s kept separate, removal of the Harvester could be somewhat easier, depending on how things are engineered. But I think it would be a major engineering challenge to include a heat exchanger/radiator within the Harvester cage under the vehicle. Placing an air source heat exchanger directly below the passenger space, under the vehicle where there’s minimal air flow, is fraught with many potential problems. They will almost certainly need to have that be a remote part that needs to be disconnected.
But I’m just making guesses…
I will never trust the images in a patent application. Those aren’t meant to give a competitor the means to reverse engineer the system, they’re meant to give the patent office a visual to sort-of explain what they’re thinking without giving away the details before the thing is even in production.
Jamie's already mentioned a few things contrary to the patent images, so I'm there with you.
Being a taller SUV/truck with a good bit of airflow running under the vehicle, and with an inherent tendency to have a low pressure wake behind the rear bumper area aerodynamically, I'm wondering if they can tap that air for both cooling the engine and improving airflow. That'd likely imply some vents in the rear bumper, but it'd be an interesting solution.
I imagined something similar, but they’ve said the bumper would be modular and replaceable. So I don’t think they’ll put any kind of thermal management in there.
There are three major problems with the underbody thermal management approach anyway (three that I can think of at this moment). First, the low pressure zone really only exists at speed, so they’d still be fighting heat build-up at lower speeds. Second, there’s a low-pressure boundary layer where the air-vehicle boundary is beneath the vehicle, so the air speed is generally lower right where they would need it to be higher—at the contact with the vehicle. Third, they want to reduce the size of or eliminate the lowest pressure zone behind the vehicle for improved Cd and reduced drag. That low pressure zone “pulls” on the back of the vehicle, reducing its efficiency in moving through the air. They may chose to use it anyway, but they may be trying to make it as small as possible, which may create a tension between the thermal management team and the Cd team.
That’s not to say they’re not figuring it out. Just that it seems to me to be a more complex solution than just running some cooling lines in parallel to the battery and motor cooling lines up to the front of the vehicle where they’re likely to have the rest of the thermal management solutions.
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The graphic here displays the air velocity magnitude of the airflow for various vehicle models. You’ll notice that airflow speeds are relatively low up near the underbody of the vehicles, both in front of and behind the rear axle. Scout Motors would have to create a positive pressure condition (fan) to push hot air into the low velocity/low pressure zones. This is possible, of course, but it might not be desirable for Cd and other reasons.
citation:
An Extensive Validation of an Open Source Based Solution for Automobile External Aerodynamics
March 2017SAE Technical Papers
DOI:10.4271/2017-01-1524
And, of course, this is all speculation until Scout releases more information. Just fun mental exercises to think about how they might solve the various complications… I’m certainly not saying I know what solution they’re going to find. I’m not an automotive engineer, much less an automotive engineer on the Scout Motors team.
Same, I'm just speculating since we have time to kill. It's fun to guess how they're going to fill in the gaps.
