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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:D
 

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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).

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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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.

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.

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.

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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Discussion Starter #4
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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Discussion Starter #5
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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Discussion Starter #7
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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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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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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Discussion Starter #12
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.
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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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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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.
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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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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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. :rolleyes: 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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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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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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Desired Characteristics

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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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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