# Help me decide what drivetrain is best.



## AdamAnDrone (Mar 23, 2017)

I have an idea for an eREV that is a 1/4 ton truck kind of like a ranger or an s10. I'm having a dilemma as to what kind of drivetrain I want to use. 4WD is a must but the main question is one big motor or two small motors one in front and one in back. Also transmission or no transmission. I'm having trouble weighing the pros and cons of each. The problem with a single motor is there needs to be a transfer case, a center diff, and two driveshafts. These are all heavy and expensive parts. On the two motor side the motors need to be inside the frame of the truck so they don't take a beating from being on an axle and so close to the ground. That means independent suspension all the way around. Which is expensive and complex. Also, I don't know if what I want to do is really good for one motor. The biggest problem is it needs to be able to tow at least 3500lbs and with the vehicle weighing a good 4000lbs I'm going to need motors that are capable of moving a good 8000lbs down the highway / through the mountians safely. I'm pretty sure that two motors, even if each was half as powerful as a single, bigger motor, would have an easier time with towing. There is also the problem that there isn't a good way to lock the front to the rear axle with two motors, which is not ideal for hardcore off-roading, which it also needs to be able to do. But If I have two motors then that means I may need two transmissions if I do need them, which wouldn't be ideal. The whole point of the truck is simplicity and reliability so a transmission with a clutch dosen't really align with those principles. It would really help me out if you could tell me what motor It would need to move 8000lbs down the road, and whether they should be AC or DC. I'm looking at the AC-51 and also the warp11 as good candidates. If you could help me decide whether a transmission is worth it and whether or not to use two motors. Basically just tell me how you would do it?

Also, this is my first post so go easy on me


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## brian_ (Feb 7, 2017)

AdamAnDrone said:


> I have an idea for an eREV that is a 1/4 ton truck kind of like a ranger or an s10.


... or a Tacoma (presumably first generation which is smaller and cheaper than more recent Tacomas), or a Nissan Frontier (again, older is smaller).



AdamAnDrone said:


> Also, I don't know if what I want to do is really good for one motor. The biggest problem is it needs to be able to tow at least 3500lbs and with the vehicle weighing a good 4000lbs I'm going to need motors that are capable of moving a good 8000lbs down the highway / through the mountians safely. I'm pretty sure that two motors, even if each was half as powerful as a single, bigger motor, would have an easier time with towing.


That's a lot of work for the drivetrain. It would take an enormous amount of battery capacity to get any useful range, so I assume that any towing trip would involve running the engine (since I assume eREV means a plug-in series hybrid with an engine-driven generator).

For the workload issue, I don't think one motor or two matters, except for the question of availability. There is a single electric motor for any desired power level... although not necessarily of the type you want or cheaply enough.


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## brian_ (Feb 7, 2017)

AdamAnDrone said:


> The problem with a single motor is there needs to be a transfer case, a center diff, and two driveshafts. These are all heavy and expensive parts.


Yes, and they also get in the way of mounting anything under the floor between the frame rails, which is presumably where you want to carry a lot of batteries.



AdamAnDrone said:


> On the two motor side the motors need to be inside the frame of the truck so they don't take a beating from being on an axle and so close to the ground. That means independent suspension all the way around. Which is expensive and complex.


The stock front suspension is independent anyway on any of these trucks, so that shouldn't be a problem.

If you don't want to arrange independent rear suspension (which is understandable), then you can mount the motor (and probably a reduction gearbox) where the original transmission was, or further rearward to free up space forward. Just keep enough propeller shaft length to allow for suspension movement.



AdamAnDrone said:


> There is also the problem that there isn't a good way to lock the front to the rear axle with two motors, which is not ideal for hardcore off-roading, which it also needs to be able to do.


I don't think this is necessary at all. Locking front and rear axle speeds together is not good - even off-road - unless you are going in a straight line. The only reason it is traditionally done by 4X4s is that they don't have any way to separately control front and rear axle speeds, so one axle can spin when it has less traction; however, with separate front and rear electric motors, you can control the speed of each appropriately.



AdamAnDrone said:


> But If I have two motors then that means I may need two transmissions if I do need them, which wouldn't be ideal.


That is certainly a problem. If nothing else, shifting them in a coordinated way is a pain.

If your transmissions are simple enough and especially if they are single-speed, this might not be so bad.

In the front, perhaps a chain drive from the motor to the stock final drive unit (differential) would be sufficient. The chain drive can be chosen to have a reduction ratio so that the combined effect of the chain drive and the ring-and-pinion gears of the final drive is appropriate. If your "range extender" engine is in the stock engine position, the front drive motor would probably need to be located well rearward, driving the front axle using a shaft similar to the stock 4WD configuration (maybe even the stock shaft).
For the rear, maybe the stock 4WD transfer case to provide two gear ratios, plus the "shortest" (numerically highest, most gear reduction) gear available in the axe, could provide acceptable low-speed and high-speed gearing. Obviously it's easy to connect a transfer case to the rear axle (that's the stock configuration), and transfer cases bolt on to transmissions so an adapter to the motor should be possible; you would need to confirm that you can shift the transfer case while moving (by interrupting motor power) without a clutch.


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## AdamAnDrone (Mar 23, 2017)

Thanks for the response you made some really good points. I particularly liked your statement that just because there are two motors dosen't necissarily mean they need to be on the axles. Now I'm considering having two motors in the middle of the truck where the transmission would be then driveshafts to the front/rear. The motors could have a locker between them (I'm not sure if thats really necessary) but it definitely eliminates the need for a center diff and transfer case either way. You were right that I want it to be an extendend range vehicle because I know towing would absolutely wreck a full electric vehicle's range. I still don't know what motors on the market right now could do what I need them to. Also I know a solid axle in the front and rear would be way simpler but would it still be able to provide a sufficient ride quality? 
Again, thanks for responding!


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## AdamAnDrone (Mar 23, 2017)

The problem with using a transfer case low range as a first gear is that as far as I know transfer cases aren't synchronised so in order to shift you would need to stop which wouldn't be helpful for towing on the road. 

Also Brian this wouldn't be a conversion but a full scratch build. I might seem crazy but I want to create a company to manufacture these vehicles. I think this eREV 1/4 ton has great potential. 

@brian_


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## rmay635703 (Oct 23, 2008)

Or you could just buy a street legal AC35 powered miles zx40st pickup for $500 and add fwd and lithium.


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## AdamAnDrone (Mar 23, 2017)

rmay635703 said:


> Or you could just buy a street legal AC35 powered miles zx40st pickup for $500 and add fwd and lithium.


bruh. Those trucks are trash. I just looked them up and the max GCVWR which is the weight of the vehicle and its cargo is 3000 lbs. This kinda bull really upsets me. People think "people want pickups so let's make an electric pickup." The technology is there. The market is there. They could make something truly awesome but then they go and make something that makes people question your sexuality every time you get in! No wonder they went bankrupt!


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## ken wont (Jul 6, 2016)

AdamAnDrone said:


> They could make something truly awesome but then they go and make something that makes people question your sexuality every time you get in! No wonder they went bankrupt!


" question your sexuality" ?? Is your name really Adam_AnDrogynous?_


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## AdamAnDrone (Mar 23, 2017)

ken wont said:


> adamandrone said:
> 
> 
> > they could make something truly awesome but then they go and make something that makes people question your sexuality every time you get in! No wonder they went bankrupt!
> ...


ayyyy lmaoo!!


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## brian_ (Feb 7, 2017)

AdamAnDrone said:


> The problem with using a transfer case low range as a first gear is that as far as I know transfer cases aren't synchronised so in order to shift you would need to stop which wouldn't be helpful for towing on the road.


Yes and no... some are shiftable on the fly, but with limitations on speed. It is certainly something which would need to be checked.


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## brian_ (Feb 7, 2017)

AdamAnDrone said:


> Also Brian this wouldn't be a conversion but a full scratch build. I might seem crazy but I want to create a company to manufacture these vehicles. I think this eREV 1/4 ton has great potential.


The idea is likely economic insanity , but a clean-sheet design would certainly allow a more optimal design for the purpose.

An independent suspension gets a lot more practical when you are custom-building the chassis. There are lots of independent rear suspensions with sufficient capacity, and avoiding the beam axle would allow the rear motor to be at the rear axle, making packaging of the rest of the components a lot easier.

The generation of the Nissan Pathfinder which was derived from the Frontier pickup has a high-capacity and compact independent rear suspension... just for an example.

While I doubt that there is an economically viable market for a light pickup with a very expensive powertrain, the justification is greater with larger trucks so there are a few commercial ventures. Some are essentially conversions and place the drive motor in the stock transmission location (e.g. Wrightspeed Route™ 250), and some appear to place the motor on a beam axle (e.g. Wrightspeed Route™ 500 and 1000), but the Nikola proposal uses independent suspension to accommodate large drive motors at the axle locations without excessive unsprung weight. Independent truck suspensions in any desired size are readily available, but I would be cautious about putting much faith in any specific information published by Nikola Motor - their information about their proposed truck (the One) is riddled with technical errors suggesting that the person who put the site together knows nothing about trucks.

In a purpose-built chassis, it would be relatively easy to mount the engine-generator unit transversely to allow the front drive unit to use a transverse motor position, like the drive units of common mass-production battery-electric cars (Leaf, etc). You might even consider using two Leaf drive units - or whatever similar unit can be purchased for one at each axle. Suspensions and drivetrains often collide - you need to ensure that the suspension design allows space for the motor and gearbox (whether single-speed or multi-speed), and a transverse motor and gearbox will be wider than the final drive (differential) normally found in the middle of an independent rear suspension.


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## AdamAnDrone (Mar 23, 2017)

brian_ said:


> AdamAnDrone said:
> 
> 
> > Also Brian this wouldn't be a conversion but a full scratch build. I might seem crazy but I want to create a company to manufacture these vehicles. I think this eREV 1/4 ton has great potential.
> ...


Interesting. I currently have it drawn out with solid axles and leaf springs all the way around, but you are right that there will be a lot of unsprung weight. It will be sort of like riding in a cottonball at the end of a spring. I liked this because it was a very simple and modular design. If I did use any other suspension it would be a double A-arm type. Do you think it would be worth losing some simplicity at the expense of cost and better ride? What if it were leaf sprung in the rear with A-arms in the front? This is probably the best solution but is also the most costly. This way I can't have the very simple modular axle and super simple manufacturing process. There is also the idea of designing a modular wishbone system that can go front and rear. The front and rear would probably need to be different because the front would need an offset for camber in turning (maybe) but that would be a problem when loading the rear suspension. What would you do? If you were buying one what would you want it to have?


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## rmay635703 (Oct 23, 2008)

If you want something that is actually efficient take a look at a VW rabbit pickup.

In diesel form with an electrically motivated rear transaxle you would gain car like EV range plus a proven 50mpg ICE range extender, add a simple rear cradle and a little better sheet metal and such a platform could be a 1 ton 1/2 ton, quarter ton whatever .

See link for an ideal rear transaxle for converting a FWD ICE pickup/SUV into 4wd.

http://ecomodder.com/forum/showthread.php/hot-rodding-toyota-mgr-29878.html

Another option

http://ecomodder.com/forum/showthread.php/1946-chevy-prius-truck-34935.html

http://ecomodder.com/forum/showthread.php/mer-chevy-project-biofuel-40mpg-pickup-7385-12.html

GMs former CEO makes EREV pickups and the VTrux concept

http://gm-volt.com/2017/03/23/workhorse-pickup-gets-fleet-support/
Of coarse workhorse wants to enter the quarter ton market as well

So to have any traction you would need to be less expensive, more efficient, more unique, more aerodynamic 

Otherwise anemic range VRS cost will drown your effort out.


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## AdamAnDrone (Mar 23, 2017)

rmay635703 said:


> If you want something that is actually efficient take a look at a VW rabbit pickup.
> 
> In diesel form with an electrically motivated rear transaxle you would gain car like EV range plus a proven 50mpg ICE range extender, add a simple rear cradle and a little better sheet metal and such a platform could be a 1 ton 1/2 ton, quarter ton whatever .
> 
> ...


The rabbit pickup is very similar to what I want to build, It would be perfect for a prototype build. It was FWD? Workhorse's pickup is nothing to scoff at. I'm sure whatever 1/4 ton they build will be pretty good. All of whatever I build will be almost the same, keeping cost down, then the customer builds it up to whatever they want.


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## brian_ (Feb 7, 2017)

The Rabbit pickup was quite small for the target use, and probably not nearly strong enough structurally. It also hasn't been produced for decades, although there are various newer versions: the Rabbit name was used for first generation of the Volkswagen Golf, and only in North America. An rebuilt old Rabbit pickup would not be a viable commercially-produced vehicle, and even for a homebuilt project or prototype a body in sound condition would probably be hard to find.

Worldwide, Volkswagen uses the "Caddy" name on the van and pickup variants of the Golf. There's a decent summary in Wikipedia: Volkswagen Caddy. These vehicles are derivatives of the Golf/Rabbit, which means that they are unibody, front-wheel-drive (which AWD recently available as an option), and compact. Engines are generally 4-cylinders, and are transversely mounted. Front suspensions are McPherson strut. Rear suspensions are independent, changing in design over the generations.

Even a modern Caddy is still small for truck in North America towing a 3500 pound trailer, although it has grown since the original. There's even a 4Motion version now (meaning that it is designed to accommodate all-wheel drive), but this would be an impossibly expensive design to copy in very small volume production. I doubt VW would sell them in "glider" form (a vehicle complete except for drivetrain), but I suppose that's a possibility.

There are similar small pickups (sometimes called "coupe utilities) from other manufacturers, but none have been offered in Canada or the United States since the Rabbit pickup and similar Dodge Rampage because there is an insufficient market for anything that small. In a larger size that might be more suitable for the target use, somewhat similarly styled vehicles were popular in Australia, but they were rear-wheel-drive and have gone out of production. The Caddy is currently offered in Mexico, although the "Caddy" name is only used for the van; it appears that the pickup is called the Saverio.


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## brian_ (Feb 7, 2017)

The Workhorse proposal is most certainly not a "1/4 ton". It is a Class 2 truck (with a GVWR of 7200 pounds) with over a ton of payload... although the numbers provided by Workhorse seem implausible - I don't think it will be that light. It is generally the same idea as Adam is proposing, but on a larger scale.

Although Workhorse is a serious manufacturer, the "W-15 4WD Plug-in Electric Pickup Truck" looks like a school design project, with most technical details missing... but someone has a 3D CAD program.  The general configuration does make sense, or could if the actual design is done well.

It has the engine and generator set transverse behind the front axle line, with a transverse front drive motor ahead of it. This makes sense to me, but only works if the component sizes are compatible with the frame width and suspension design. Workhorse builds truck chassis and so would design to ensure this compatibility; anyone working with an existing vehicle may have challenges.

The reference on the Workhorse site to a "BMW range extender" is interesting, as the only "range extender" package currently produced by BMW is the optional one in the back of an i3, which has far too little power output to provide indefinite operation (with just refuelling) of a vehicle of this size and payload. They are apparently referring to some proposed product with a larger engine.


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## brian_ (Feb 7, 2017)

rmay635703 said:


> See link for an ideal rear transaxle for converting a FWD ICE pickup/SUV into 4wd.
> 
> http://ecomodder.com/forum/showthread.php/hot-rodding-toyota-mgr-29878.html


Sorry, I didn't take the time to read all 401 posts of that EcoModding thread (only the first 80); it may have covered what I'm going to say. I did jump to the last 20 posts, and it doesn't look like this discussion resulted in this unit being used to actually drive a vehicle.

The Highlander Hybrid (and Lexus RX hybrid) rear drive unit is a nice package, with an excellent motor (the "MGR", meaning "Motor-Generator, Rear") and integrated two-stage spur-gear reduction gearset (overall reduction ratio 6.86:1) and differential. The motor is similar to the MG2 (motor-generator on the output side of the power-split Toyota Synergy Drive) in the larger transverse Toyota hybrid transaxles, but apparently not as large as the MG2 of the rear-wheel-drive Toyota (Lexus IS, GS, and LS hybrid versions) transmission.

The Toyota RAV4 Hybrid and Lexus NX hybrid use the same drivetrain design. I don't know if they use the same MGR, or a similar but smaller unit (since they are smaller vehicles than the Highlander/RX). The only other AWD Toyota/Lexus hybrids are LS sedans with the longitudinal drivetrain and drive the rear mechanically, rather than using an electric drive unit.

Unfortunately, it is not intended for continuous use, and so does not have enough sufficient cooling capacity to be the drive unit of an EV. There is no liquid cooling circuit as provided for the MG2 (although it appears that gear oil might spray on the end of the motor windings), or air cooling fan; there is no pump or external cooler for the gear oil. In the Highlander it is only used to drive when front wheel traction is inadequate, and presumably for regenerative braking. Highlander Hybrid owners have had problems with the rear drive unit protectively shutting down if they try to drive through low-traction situations for extended periods. I don't know if the EcoModding member or others have resolved this issue, although early in the thread I see there are comments which suggest that just pumping gear lube through it was expected to be enough... which seems unlikely.

The EcoModder also expects to make this part-time drive unit more durable by improving the gears built by Aisin (Toyota's transmission supplier). That seems unlikely to me.

Of course, since it is a 3-phase AC permanent magnet like any other modern production hybrid or electric vehicle, a suitable inverter - which works with the motor's resolver - is required to drive it.


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## brian_ (Feb 7, 2017)

AdamAnDrone said:


> Interesting. I currently have it drawn out with solid axles and leaf springs all the way around, but you are right that there will be a lot of unsprung weight. It will be sort of like riding in a cottonball at the end of a spring. I liked this because it was a very simple and modular design. If I did use any other suspension it would be a double A-arm type. Do you think it would be worth losing some simplicity at the expense of cost and better ride? What if it were leaf sprung in the rear with A-arms in the front? This is probably the best solution but is also the most costly. This way I can't have the very simple modular axle and super simple manufacturing process. There is also the idea of designing a modular wishbone system that can go front and rear. The front and rear would probably need to be different because the front would need an offset for camber in turning (maybe) but that would be a problem when loading the rear suspension. What would you do? If you were buying one what would you want it to have?


There's a lot to discuss here, and I'm interested in participating, but it will take me a while to get around to putting together a coherent and constructive contribution. Hang on a few more days...


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## brian_ (Feb 7, 2017)

*Desired Characteristics*



AdamAnDrone said:


> If you were buying one what would you want it to have?


I don’t think the average buyer knows what technical features they want. They know what is fashionable, they know what “everyone knows” it should have (e.g. “everyone knows a truck should have leaf springs at the rear”), but they don’t understand enough about vehicle design to know how the vehicle should be designed. What they should know is what they want it do for them: they should know their functional requirements, rather than knowing what design would meet those requirements.

Suspension design options break down most fundamentally into beam axles and independent suspensions, and many buyers have no idea what even that means. With lots of variations in complexity and performance of each type, most buyers have no idea what they are buying. There are many valid alternatives, and the right choice is highly dependent on the requirements:

cost
ride
handling
packaging
Without understanding the requirements of the application, no rational choice of design is possible. The challenge is determining who the potential customers would be, and what their requirements are.

Pickup rear suspensions have the least demanding performance characteristics of light vehicle. As long as they don’t break under load, and are driven (no front-wheel-drive pickups), they work. Vehicles in which people ride closer to the rear axle, and vehicles which are expected to handle better, get better suspensions… simply because that is what is required to meet the performance requirements. SUVs can also justify a higher manufacturing cost, because they sell for a higher price; cost is still a critical driver, but the cost limitation is different.

(This is the first part of what will be a multiple responses to post #12)


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## brian_ (Feb 7, 2017)

The VW Rabbit Pickup - which is actually now the VW Caddy - was mentioned earlier. I now realize that there is no Caddy pickup in Mexico: the Saveiro is not a pickup version of the Golf-based Caddy, rather it is a pickup version of the even smaller Gol. It is from Brazil, where these little pickups - such as the Chevrolet Montana - are popular.

There is one vehicle of this style currently sold (and therefore certified compliant with federal regulations) in Canada and the U.S.: the *Honda Ridgeline*. The Ridgeline is probably larger than desired for this discussion, but it is a pickup truck with unibody construction, all-independent suspension, and all-wheel-drive. If the entire drivetrain were removed, an engine-generator set could be mounted in the front along with drive motor units (with suitable gearboxes) at each axle position, using the stock suspension. The front suspension is struts, so it provides good clear width in the engine compartment.

Honda builds a non-plug-in hybrid drivetrain for this vehicle platform; the platform is shared between the Acura MDX, Honda Pilot, and Honda Ridgeline. This drivetrain is a parallel hybrid, with dual-clutch transmission and a motor-generator at the front, and a two-motor (driving each wheel separately) unit at the rear (functionally similar to the Highlander Hybrid rear-drive unit). The hybrid system does not intrude into the vehicle interior in the SUVs, and the Ridgeline has even more space available under the floor due to the extra wheelbase. 

So far Honda has only offered the hybrid system in the MDX, with the Pilot coming, but I have not heard even a rumour of a Ridgeline hybrid. So...

Would it make more sense to convert a Ridgeline to plug-in hybrid (using the Honda system plus extra battery) than to build something custom?
If Honda doesn't see a market for a hybrid pickup even though they could build it entirely with components already in production, is there a market for an even more expensive "eREV" in this style of vehicle?


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## brian_ (Feb 7, 2017)

brian_ said:


> ... I have not heard even a rumour of a Ridgeline hybrid.


Okay, I now realize that there is some chatter about a Ridgeline hybrid. Most of it has been wild speculation in advance of the release of the actual 2016 Ridgeline, with no foundation in reality. One Motor Trend article was published since the 2016 Ridgeline came out, but still refers to a hybrid Pilot as speculation, so clearly they had no actual information about which models would get a hybrid drivetrain. Another article in TheFastLaneTruck.com is written by someone who isn't even aware of the MDX hybrid, so it's clearly meaningless prattle. Some of these are based on broad comments by Honda people at the 2017 North American International Auto Show, extrapolated speculatively to the Ridgeline.


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## dain254 (Oct 8, 2015)

Sure the technology is there, but using a pickup for pickup duty is going to kill battery life 4x as fast if not more. Read up on some of the examples of Tesla Model X owners who do any towing... something like 900-1000wh/mile - to legitimately make a pickup able to do pickup duties a person would need minimum 150kwh battery... and at Tesla Model X consumption would still only get 150 miles. IS it possible? sure - but very few people spend $150k on a pickup (assuming the $1000/kwh that Tesla charges on it's fleet)


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## brian_ (Feb 7, 2017)

dain254 said:


> Sure the technology is there, but using a pickup for pickup duty is going to kill battery life 4x as fast if not more. Read up on some of the examples of Tesla Model X owners who do any towing... something like 900-1000wh/mile - to legitimately make a pickup able to do pickup duties a person would need minimum 150kwh battery... and at Tesla Model X consumption would still only get 150 miles.


I assumed that towing would require engine operation, and Adam confirmed that in post #4. Battery-only operation would be for the non-towing time; for towing whatever battery charge it starts with would just be a head-start on the energy needed for the trip.



dain254 said:


> IS it possible? sure - but very few people spend $150k on a pickup (assuming the $1000/kwh that Tesla charges on it's fleet)


Although I don't know that Tesla pricing is applicable to this class of vehicle, I agree that the product economics are challenging... my assessment was "economic insanity", but I applaud anyone who can find a design which can pull this off.


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## AdamAnDrone (Mar 23, 2017)

I found this http://www.evsource.com/tls_warp11.php which says that if I used a warp9 in the front and another in the rear I could give a 4000lb truck a tow capacity of 3200lbs. A respectable number for a 1/4 ton truck. On the other hand if it had two warp13s It could tow 1000lbs, which would not be ideal for a 1/4 ton truck. That peak torque of 1280lb/ft would come in handy while passing on the freeway, though.


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## AdamAnDrone (Mar 23, 2017)

This thread is getting a lot of attention! Thanks a lot any design input is greatly appreciated! 

After some more design consideration I think I have the suspension system sorted out. I'll probably want to stick with a modular independent trailing arm suspension with coil springs. Modular meaning that the arms and such from the front left are exactly the same as the ones from the back right. The only differences arise when you have to put steeing components on the front.

I have also done some calculations on the feasability of continuous operation while towing through a generator. I will post some more detailed info / calculations tomorrow. I am looking at a small turbo diesel Cummins is making with a peak output of 210hp. The key is that it produces peak torque at only 1800rpm and the fact that it is a turbo diesel means it should be very efficient and able to run off biodiesel. That way to recharge the battery on say a road trip the engine can just crank up and rev to 1800 and just sit there, which would hopefully be enough to recharge the batteries (albeit maybe slowly) while driving around without a load, while the engine is at peak efficiency. Then if you are towing or encounter a ricer and need some extra juice the engine can rev up higher and you shouldn't have any problems considering the 2011 ranger 4.0 V6 makes almost that same amount of HP and can tow 5800lbs according to Ford.

If you really want I'll post a drawing of the truck too. Also is the peak torque of an engine actually it's most efficient RPM?


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## Duncan (Dec 8, 2008)

The peak efficiency is usually at peak torque

Why not use the Cunnins to drive the vehicle - it will be about 20% more efficient than using as a series hybrid

- as far as your Warp 9's are concerned - remember the maximum continuous power will be about 25 Hp - if you have a heavy load you will need to be going slowly


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## Karter2 (Nov 17, 2011)

Does it have to be a pick up ?
Mitsubishi make a very (off road) capable 4X4 SUV with full EV drive, series/parallel Hybrid drive,.......... and 3000+ lb towing capacity......
......their Outlander PHEV. http://www.motoring.com.au/hybrid-vigour-mitsubishi-outlander-phev-rally-car-100031/
It uses dual motors..one for each axle, and a 150kw ICE for generation and/or drive power.
Its the most successful hybrid in Europe.
.......but its not a pick up !
Its probably easier and cheaper to chop the roof off one of these than attempt some of the ideas proposed above !


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## AdamAnDrone (Mar 23, 2017)

Duncan said:


> The peak efficiency is usually at peak torque
> 
> Why not use the Cunnins to drive the vehicle - it will be about 20% more efficient than using as a series hybrid


There's where your wrong, kiddo. When you consider that the engine can be run at peak efficiency in a series hybrid it can actually be more efficient than an engine with a transmission. In a conventional vehicle the engine is only about 15% efficient because it has to operate in a large rpm range. When at peak efficiency, however, an ICE can be upwards of 30% efficient. That alone makes this system 2x as efficient. The hybrid system isn't perfect, though. There is some loss in converting the mechanical energy into useable electrical energy. The majority of these losses come when charging / discharging the batteries. Even still I figure a traditional system is only about 17% efficient while a hybrid system can be 21% efficient. Admittedly these numbers change when the vehicle is towing or under load and the engine has to run outside it's peak efficiency. Then it could drop to 14% efficient. Here's how I came up with these numbers.

Traditional system:
20% efficient engine
85% efficient drivetrain

Hybrid system:
30% efficient engine
95% efficient generator
95% efficient charger
85% efficient batteries
90% efficient motor

I've also drawn out the electrical system as having the motor and charger in parallel from the generator. I've wondered what the feasability of having some kind of contactor / disconnect system which lets the generator be directly connected to the motor. In this system while towing the vehicle could have an efficiency similar to an ICE while towing, in theory. Then there is the issue of how to keep the battery charged for the accessories and such. I thought originally I could just put the charger and motor in parallel to the generator so that whatever current the motor was gonna draw it could then the charger got the leftover for the batteries but problems arise when the engine isn't running now the generator and motor are in parallel and the generator is going to try and turn the engine which would definitely cause problems. I just can't seem to wrap my head around how this should be done unless there is just some "smart" power management system that distributes and allocates power.

These are estimates, of course and I'm interested to see what you all think of my numbers. It is key that the design principle is a good one from the start, so all criticism is greatly appreciated.


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## AdamAnDrone (Mar 23, 2017)

Karter2 said:


> Does it have to be a pick up ?
> Mitsubishi make a very (off road) capable 4X4 SUV with full EV drive, series/parallel Hybrid drive,.......... and 3000+ lb towing capacity......
> ......their Outlander PHEV. http://www.motoring.com.au/hybrid-vigour-mitsubishi-outlander-phev-rally-car-100031/
> It uses dual motors..one for each axle, and a 150kw ICE for generation and/or drive power.
> ...


That thing is certainly cool but there's just something about pickup trucks, I'm even considering a flatbed which would allow for super simple camper conversions or whatever you want. I could put mount points for 2x4s all the way around, too. Imagine if instead of having to pay a bunch of money to have some panel repaired on the bed of your truck when instead you can just get some 2x4s and repair it yourself and get that DIY factory finish! And this helps with the idea of a modular vehicle that you build into what you want. Landscaper? Put some weedeater racks on there! Farmer? put some tall walls on the bed and haul hay bales. Hobo? Build a tiny house on the bed of your truck!

If I were to build any different type of vehicle it would be a 4x4 SUV most likely. They and pickups can satisfy almost every vehicle need ever. Pickups get the work done and SUV's get everyone to the job site! Pickups are just my personal favorite so that is what I want to build.


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## AdamAnDrone (Mar 23, 2017)

brian_ said:


> I assumed that towing would require engine operation, and Adam confirmed that in post #4. Battery-only operation would be for the non-towing time; for towing whatever battery charge it starts with would just be a head-start on the energy needed for the trip.


You got it. When you say it like that it makes me think a paralell hybrid might be the way to go!  I'm not convinced, though. Series eliminates the need for a transmission which are pretty crappy. At the same Time you get that instant torque, great for having fun. And hey, that's what a prius has and I ain't tryin' to build no ding dang hippie machine! . The bottom line is if its objectively better it's what I want so I'll still look into it.


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## Duncan (Dec 8, 2008)

AdamAnDrone said:


> There's where your wrong, kiddo. When you consider that the engine can be run at peak efficiency in a series hybrid it can actually be more efficient than an engine with a transmission. In a conventional vehicle the engine is only about 15% efficient because it has to operate in a large rpm range. When at peak efficiency, however, an ICE can be upwards of 30% efficient. That alone makes this system 2x as efficient. The hybrid system isn't perfect, though. There is some loss in converting the mechanical energy into useable electrical energy. The majority of these losses come when charging / discharging the batteries. Even still I figure a traditional system is only about 17% efficient while a hybrid system can be 21% efficient. Admittedly these numbers change when the vehicle is towing or under load and the engine has to run outside it's peak efficiency. Then it could drop to 14% efficient. Here's how I came up with these numbers.
> 
> Traditional system:
> 20% efficient engine
> ...



TOTAL BOLLOCKS - absolute BOLLOCKS

First while an Atkins cycle engine can be a little bit more efficient than an Otto cycle we were talking diesel here and they are DIFFERENT
I do have a little experience with those (24 years in engine test and development)
Using a Cummins at it's most efficient will be better - BUT that is where you gear the thing to operate most of the time! 

Traditional system:
20% efficient engine
85% efficient drivetrain
*Total - 17%*

Hybrid system:
*25* % efficient engine - I'm allowing you a good bit here more than is reasonable!
95% efficient generator
95% efficient charger
85% efficient batteries
90% efficient motor
85% efficient drivetrain - _you missed this bit - the same losses at the IC engine_
*Total - 12%*
You still need the reduction gear, diff and tires - so your 85% for an IC - to the ground is the same as for an electric

*25* % efficient engine - I'm allowing you a good bit here more than is reasonable
95% efficient generator
_*95% efficient charger 
85% efficient batteries*_* take these bits out as you are going from the generator to the motor*
90% efficient motor
85% efficient drivetrain - _you missed this bit - the same losses at the IC engine_
*Total - 18%*
By assuming an unreasonable increase in efficiency - we get a small increase in overall efficiency

Now - an Atkins cycle engine is a wee bit more efficient than an Otto cycle 
But you don't get that by simply breaking a bottle of champagne on an engine and announcing that it is an Atkins cycle - you need to substantially change the intake valve timing are you up for that level of change?? and can you do all of the other things like timing and injection maps to support the change?

There is a reason that there are very few diesel hybrids - a petrol hybrid takes advantage of a petrol engines reduced efficiency a part load
With a diesel that reduction is much much less - so there is less to go for and the disadvantages stay the same

Hybrids are great - in their place - city traffic - lots of stop/go

As soon as you move away from there their advantages evaporate

Plug-In hybrids are different - they basically are EV's most of the time accepting a WORSE fuel economy than a normal car when they have to burn fuel for a long range (rare) trip


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## Karter2 (Nov 17, 2011)

You wont get an electric motor to operate at 90% efficiency over much of its rpm range either !
So unless you are planning on just a constant cruising speed, you can knock 10%+ off that motor efficiency number.


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## brian_ (Feb 7, 2017)

AdamAnDrone said:


> ... I'm even considering a flatbed which would allow for super simple camper conversions or whatever you want. I could put mount points for 2x4s all the way around, too. Imagine if instead of having to pay a bunch of money to have some panel repaired on the bed of your truck when instead you can just get some 2x4s and repair it yourself and get that DIY factory finish! And this helps with the idea of a modular vehicle that you build into what you want. Landscaper? Put some weedeater racks on there! Farmer? put some tall walls on the bed and haul hay bales. Hobo? Build a tiny house on the bed of your truck!


Those are popular in other parts of the world, but not here in North America. There are two issues with them:

The deck is over the tops of the tires, so it is high - very high with the large tires which people want here.
Without sides, you really can't carry anything without also carrying a box for it or strapping it down, but people want to toss stuff in the back.


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## brian_ (Feb 7, 2017)

AdamAnDrone said:


> After some more design consideration I think I have the suspension system sorted out. I'll probably want to stick with a modular independent trailing arm suspension with coil springs. Modular meaning that the arms and such from the front left are exactly the same as the ones from the back right. The only differences arise when you have to put steeing components on the front.


I have some more notes underway about the suspension issues, but first...
Do you really mean *trailing arms*? I haven't heard of a road vehicle using trailing arm front suspension for decades. We're talking VW Beetle level of design here. Do you have a drawing (even very rough), or a link to an illustration of a similar design?


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## brian_ (Feb 7, 2017)

AdamAnDrone said:


> I am looking at a small turbo diesel Cummins is making with a peak output of 210hp.


As far as I know, Cummins has no small engines available for road vehicles in North America. The only two Cummins products in "light" trucks here are the 5.0L V8 (in the Nissan Titan XD) and 6.7L L6 (in the Ram Heavy Duty).

The ISF2.8 was shown in a Nissan Frontier, but only as a promotion. These four cylinders - the ISF2.8 and the ISF3.8 are only certified in Europe; I doubt they would sell you one here... but maybe. Neither puts out as much as 210 hp... for that you need a low-power trim of the ISB6.7 (same series as the Ram pickup 6.7). The only "small" (under 5.0 L) diesel engines found in light trucks in North America which put out over 200 horsepower are the V6s which are also found in cars.

Which engine are you thinking of?


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## brian_ (Feb 7, 2017)

AdamAnDrone said:


> ... Then if you are towing or encounter a ricer and need some extra juice the engine can rev up higher and you shouldn't have any problems considering the 2011 ranger 4.0 V6 makes almost that same amount of HP and can tow 5800lbs according to Ford.


Rated towing capacity has little to do with power, and everything to do with durability and ability to avoid overheating. Any Corvette engine puts out far more power than that Ranger, but a Corvette's towing rating is zero.


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## brian_ (Feb 7, 2017)

AdamAnDrone said:


> If you really want I'll post a drawing of the truck too.


Yes, please.


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## brian_ (Feb 7, 2017)

AdamAnDrone said:


> Also is the peak torque of an engine actually it's most efficient RPM?


Not necessarily, but it won't be too far off. One problem is that most published engine performance data is only for full-load conditions; although the most efficient state will be at high load, it may not be at full load. It's very unlikely to occur at higher engine speed than the peak torque speed, due to frictional and pumping losses.


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## ken wont (Jul 6, 2016)

AdamAnDrone said:


> That thing is certainly cool but there's just something about pickup trucks, I'm even considering a flatbed which would allow for super simple camper conversions or whatever.


You could just buy a used vehicle like this one.

Test driving the Lansden Electric truck on Grand Avenue in Los Angeles
1912
Source: Huntington Digital Library


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## AdamAnDrone (Mar 23, 2017)

ken wont said:


> AdamAnDrone said:
> 
> 
> > That thing is certainly cool but there's just something about pickup trucks, I'm even considering a flatbed which would allow for super simple camper conversions or whatever.
> ...


Whoa! Way too high tech and complex!


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## AdamAnDrone (Mar 23, 2017)

Its a new engine they are making here's an article about it.

http://m.cumminshub.com/2.8l-cummins.html


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## AdamAnDrone (Mar 23, 2017)

brian_ said:


> AdamAnDrone said:
> 
> 
> > If you really want I'll post a drawing of the truck too.
> ...


If you insist!

The actual truck wouldn't have such big tires. I'm also considering a flatbed or extended cab.


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## AdamAnDrone (Mar 23, 2017)

brian_ said:


> AdamAnDrone said:
> 
> 
> > After some more design consideration I think I have the suspension system sorted out. I'll probably want to stick with a modular independent trailing arm suspension with coil springs. Modular meaning that the arms and such from the front left are exactly the same as the ones from the back right. The only differences arise when you have to put steeing components on the front.
> ...


Yes I liked it because of how simple it was and it also would give great articulation off road and I thought it would be easy to make modular with coil springs. I do know a lot of older fords f-150's had trailing arm suspension in front. I wanted to do it a little different I'll attach two images, one of the old ford design, which I don't like, and one of something I think could work.

In the diagram one is the old ford design. This didn't look good to me. They called it pivot arm suspension and I dont like the amount of stress the bushing which connects the arm to the frame would be under.

In the other picture you can see the way I would want to do it. The picture has air bags but I think I would opt for coil springs and shocks. Its on an expedition in this pic I believe and it is custom.

I've also attatched a picture of the Dodge power wagon 2500 suspension as an example of a new vehicle with it, though it does use a solid axle.


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## brian_ (Feb 7, 2017)

AdamAnDrone said:


> Its a new engine they are making here's an article about it.
> 
> http://m.cumminshub.com/2.8l-cummins.html


That's the ISF2.8 that I linked to. The 210 hp value is not for any real production version, although I suppose if a pickup manufacturer told Cummins that they wanted to buy thousands and assured Cummins that they would only go into very light-duty use, a rating that high might be allowed for a pickup.


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## brian_ (Feb 7, 2017)

AdamAnDrone said:


> If you insist!
> 
> The actual truck wouldn't have such big tires. I'm also considering a flatbed or extended cab.


While most people really only need a single cab, it's almost hard to even give away a pickup with single cab here now. Everyone wants at least a way to recline the seat a bit, and some inside space, and a lot of people want at least an occasional-use back seat. I think it makes sense to plan on a couple of configurations, with either an extended or double cab and short box, or a shorter cab and bigger box. If the box is removable (traditional body-on-frame construction, at least at the back) it's easy to offer options or just let buyers remove the box and fit what they want.


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## brian_ (Feb 7, 2017)

AdamAnDrone said:


> Yes I liked it because of how simple it was and it also would give great articulation off road and I thought it would be easy to make modular with coil springs. I do know a lot of older fords f-150's had trailing arm suspension in front. I wanted to do it a little different I'll attach two images, one of the old ford design, which I don't like, and one of something I think could work.
> 
> In the diagram one is the old ford design. This didn't look good to me. They called it pivot arm suspension and I dont like the amount of stress the bushing which connects the arm to the frame would be under.


This is not a trailing arm suspension. "Trailing" means that the wheels are behind (so "trail") the points where the arms mount to the frame, so these are leading. Also, the half-axles and the arm section that bolt to it combine to form a single semi-leading arm (the pivot axis is not across the vehicle like a fully leading arm; it's diagonal).

The same thing at the back, facing the other way, is a semi-trailing arm suspension. It's substantially simpler without the steering, and if the vertical travel requirement is modest it worked okay... good enough for some of the best cars of the 20th century, but not considered good enough for anything today.

Ford called this Twin I-Beam when not driven, and the live (driven) version is Twin Traction Beam. They used it in all light trucks, including the F-150 pickup and Bronco SUV, Ranger pickup and Bronco II and Explorer SUVs. It was discontinued because although it is simple and reasonably durable, it is a lousy suspension with horrible angle changes with travel. In Ford's design the driven version also has the final drive riding on a suspension arm and increasing unsprung weight.



AdamAnDrone said:


> In the other picture you can see the way I would want to do it. The picture has air bags but I think I would opt for coil springs and shocks. Its on an expedition in this pic I believe and it is custom.


This is the only leading or trailing arm suspension of the three. It is not powered and not steered, so it's likely on an off-road-capable camping trailer - there are few companies in Australia which feature this design. I'm impressed that they offer long-travel independent suspensions, but they're not up to the standards of automotive suspensions.

You can use a trailing arm suspension at the rear, although it has poor response to cornering forces (it tends to toe out under cornering force, causing oversteer). At the front it is generally a bad idea to use a leading single-arm design (I can explain why if you're interested), and to make it steer is really bad (it makes the Twin I-Beam look good)... which is why I was surprised that you suggested that a trailing (or leading) front suspension.

The one in the photo does have air springs, which means it also has dampers (shock absorbers). The shocks are outboard of the springs. The only springs which are usable without shocks are leaf springs (if they have enough inter-leaf friction) and rubber blocks... but even then only for trailers and most crude heavy trucks.



AdamAnDrone said:


> I've also attatched a picture of the Dodge power wagon 2500 suspension as an example of a new vehicle with it, though it does use a solid axle.


A beam axle located by multiple leading arms and a lateral control link - such as the Ram 2500 and 3500, Ford Super Duty pickups with 4WD, and Jeep Wrangler - is an entirely different thing. It is not independent, and has completely different geometry from an independent suspension.


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