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Discussion Starter · #1 ·
Hello All!
thanks for welcoming me to the community. I've read several similar potential builds to this topic, but nothing had exactly the same parameters as what I'm sizing up.

Current Vehicle:
2005 Chevy Silverado Diesel 4x4. Good condition.

What I use it for:
Towing a camper. Do some long distance trips. 4x4'ing is nice for if traction is a real concern, but not looking to 4x4 for fun, stealth mode, etc.

Initial Idea:
Disconnect front drive shaft from transfer case and drive it from an electric motor instead. Yes, there are other threads I've found similar, but they revolve around being a 4x4 play truck where all 4 are driven by a single motor. 4x4 performance is not a concern. I only use 4x4 for when roads are treacherous. And even that is very, very limited as I work a tech job.

Use Case: I'd like to be able to use the setup for these purposes:
1) Hybrid drive: Have the main motor drive and drive the electric / charge batteries. Be able to manage the battery level in case a known uphill pull is required (both engines at higher output)
2) IC Engine only mode. For when charging batteries to full (see case 4 below) is desired .
3) Electric only mode. Likely wouldn't work for towing, but would want the ability in case of main engine failure or first leg of trip after charging from wall power.
4) Running camper electronics from battery store via Inverter. Boondocking or staying overnight at rest stops where I'd want an ample source or 110 VAC power. Assume batteries would be mostly depleted after use, and would have to resume in diesel-only mode for next trip.

Build Ideas and Concerns
1) Initial idea is to use front driveshaft as mentioned above. This model truck has an independent front so the front differential is in a fixed position. The front differential also engaged via an electric servo so a break between the front wheels and electric motor/transmission would happen there. Assume a stop needed for re-engagement.
2) Concern: Syncing the 2 systems to drive at same rate/throttle. Naturally a concern.
3) Concern: Would there be a transmission necessary for the electric drive system. driveshaft spins from 0 to an estimated 4000 rpm.
4) Opportunity: there is room underneath next to the transfer case. Of course the bed area is available for things such as the battery bank.
5) Concern: Costs. I know this won't be free. I'm assuming thousands and know this won't be free. But, I won't go to tens of thousands.

Interested to hear your thoughts. Maybe send me to a string that I haven't hit on yet. Again, I found other strings on 4x4's. But yet to see one with exactly this use case and parameters. Basically, the diesel drive system is in good shape. So this project isn't absolutely necessary to re-power the unit. I really want to do it because I'm a nerd at heart.
Thank you.
 

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While hybrid projects that are proposed in this forum almost never get built, because they are too complicated and have too little benefit, this proposal actually makes reasonable sense. :)

No, you don't need a multi-ratio transmission for the electric motor, but you either need to choose a motor which can produce (and generate) enough power at the relatively low speed of the shaft, or add an extra gearbox so the motor runs faster, or change the ring and pinion gears of the front axle for higher motor speed.
 

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Discussion Starter · #3 ·
While hybrid projects that are proposed in this forum almost never get built, because they are too complicated and have too little benefit, this proposal actually makes reasonable sense. :)

No, you don't need a multi-ratio transmission for the electric motor, but you either need to choose a motor which can produce (and generate) enough power at the relatively low speed of the shaft, or add an extra gearbox so the motor runs faster, or change the ring and pinion gears of the front axle for higher motor speed.
I'm happy at least one person thinks so. I'm not the kind of person to dig in before thinking it all through but I haven't found a good enough reason to stop considering. I really started thinking about this as when we travel and pull over for the night, we either have to run a generator for tv/ac or not and have everything but that. The big problem with the generator is the noise. Even if you can keep it to a buzz it's still an annoyance for it to run all night. So that got me thinking about a battery bank/inverter but... that costs a lot for just occasional use and... batteries are expensive and don't last forever. But if they also served the purpose of propelling the vehicle and feeding my nerd soul, then maybe there is potential.

On top of that, the mechanical part of it is actually my first love. Being a car/motorcycle guy from teens till present day. I've even built small dune buggies from big industrial engines. Not just a go kart but more like fully suspended borrowing parts from ATVs. So I cut, weld, wrench, etcetera.

As far as power requirement, I don't know. My first feeling is somewhere between 50-150hp. Too much and the extra power would steer the vehicle when both drives engaged and drain batteries (and cost a lot). Too little and the extra drive wouldn't be worth the expense and not be able to move it on electricity alone. Since I don't have a single component in my posession right now, I'm open for any and all suggestions. As for controlling it, I assume that there will need to at least be some type of gas pedal interface. I think getting into something like programming it into an ECU would turn me off to this project unless I got a lot of help.

Also the power steering/brakes would have to be addressed. At first this could be tested on by running the diesel at idle/neutral while the electric did it's job. But if I wanted to plan a stage 2 where the hydroboost was run by electric motor instead of the engine belt... that's something. This GM had one of those systems which is basically power steering pump and brake boost all in one. As for heat & A/C.... Now we're making a lot of assumptions. Heat can always be made from electricity but... First things first, I guess.
 

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I think the poor aerodynamics of a conventional truck as well as the insane additional drag from the trailer is what makes it a non-starter [utility] project. Doing it for non-practical reasons is a different story.
 

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Discussion Starter · #5 ·
I think the poor aerodynamics of a conventional truck as well as the insane additional drag from the trailer is what makes it a non-starter [utility] project. Doing it for non-practical reasons is a different story.
Yes, I don't think this would advance the cause of someone parking their Prius in favor of something like this. But there are electric trucks in the works and the universe of freight movement efficiencies is wide open. Maybe we don't get to 100%, but any percentage is a gain.
 

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Discussion Starter · #6 ·
As far as components, I'm not sure how this site is with references to particular brands or other sites. Some don't like those to be mentioned in posts. If anyone has specific things to recommend, it looks like there is a PM function though I haven't used it yet. Or if you know it's allowed, just bloop it on in a post.
 

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As far as components, I'm not sure how this site is with references to particular brands or other sites. Some don't like those to be mentioned in posts.
I haven't seen any issue with either. Sharing information about specific brands and models of components is valuable, and if the best source of some information is another forum (Endless Sphere is an example) sharing that makes sense.
 

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Most likely, a project like this will go into the several tens of thousands of $ or more, just to get started.
Maybe not. It only needs plug-in-hybrid level of battery capacity, not battery-electric vehicle level, and of course the battery is a large part of the cost. If the hybrid system is primarily an assist (rather than expecting EV mode with good performance), the motor power (and thus controller size) can be moderate as well.

It won't be cheap, though.
 

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Yes, I don't think this would advance the cause of someone parking their Prius in favor of something like this. But there are electric trucks in the works and the universe of freight movement efficiencies is wide open. Maybe we don't get to 100%, but any percentage is a gain.
Fortunately, the intended use case is not to replace a rational urban passenger vehicle.
 

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The Hybrid drivetrain GM and several other automakers collaborated on right before the 2007/2008 credit crunch might serve as a good exemplar. It was used in GM's Yukon/Escalade/Tahoe as well as some Chrysler, BMW, and Mercedes products if my memory serves me. It was their [6.0L] - [motor/generator] - [4-speed auto] - [motor] - driveshaft. My understanding is that it was a decent enough system; consumers just didn't care for them. I believe they're still used in urban buses.
 

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I think the poor aerodynamics of a conventional truck as well as the insane additional drag from the trailer is what makes it a non-starter [utility] project. Doing it for non-practical reasons is a different story.
It's worth noting that although frontal area largely cannot be reduced. The drag coefficient of vehicles have improved dramatically in recent year, although they don't conform to our intuitions about what aerodynamic looks like. Undertrays, air-curtains, small airfoils to energize the boundary-layer, and simple crisp bodylines towards the rear to faciliate clean separation. I would highly recommend Julian Edgar's books and YouTube channel - he's not an aerodynamicist by training, but an automotive journalist and enthusiast that engages with such experts.
 

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It's worth noting that although frontal area largely cannot be reduced. The drag coefficient of vehicles have improved dramatically in recent year, although they don't conform to our intuitions about what aerodynamic looks like. Undertrays, air-curtains, small airfoils to energize the boundary-layer, and simple crisp bodylines towards the rear to faciliate clean separation. I would highly recommend Julian Edgar's books and YouTube channel - he's not an aerodynamicist by training, but an automotive journalist and enthusiast that engages with such experts.
We no longer need intuition or experts - quite a few people run fluid dynamics simulations on their own to determine drag coefficients even when the numbers aren't available from the manufacturers. Either way, here is a relevant citation :

Although we don't have the new F-150's coefficient of drag (we're told that number will be released after the Ford half-ton completes EPA fuel economy certification), the 2014 Ram number is 0.360 for its regular-cab 4x2 and the 2014 Chevrolet Silverado 1500 crew cab is 0.410. All 4x2 Toyota Tundras have a 0.370, while all their 4x4s have a 0.380 Cd.

Safe to say 2005 Silverado wasn't more aerodynamic than 2014 one. Though of course there are so many variants, I am not too determined to make an apples to apples comparison.

On the other hand we have a significant list of drag coefficients for comparison available here :

Interestingly for Cybertruck the numbers vary from one source to the next. If I remember correctly Elon suggested something like 0.3, and some independent simulations reached as much as 0.48, while others were still leaning towards 0.3 due to some strange behaviors at speed.

Oh, and another relevant datapoint for these conversations is Nissan Leaf. Wiki page above suggests it at 0.29 (2010 model).
 

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We no longer need intuition or experts - quite a few people run fluid dynamics simulations on their own to determine drag coefficients even when the numbers aren't available from the manufacturers. Either way, here is a relevant citation :
I would agree that people shouldn't implement aerodynamic modifications based on their intuition, although I would say we still very much need experts. Half-decent fluid dynamics software is still expensive, and running iterations still requires significant computation x time.

Ultimately industry still uses wind-tunnels and real-world testing to verify those models. The real world is its own best model, anytime we model something we sacrifice some sort of real-world validity. Even wind-tunnels are too artificial; we do not drive through laminar flow. Vehicles need to not only be 'slippery' but stable in response to turbulant air from nearby vehicles and strong winds that aren't 0° yaw.

Since large automotive manufacturers are motivated to find a Cd reduction from .300 to .295, they need such modeling. An individual would never recoup real-world benefits from such granular efforts. Again, I wholehearted recommend Julian Edgar's resources for affordable methods of real-world testing.
 

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The Hybrid drivetrain GM and several other automakers collaborated on right before the 2007/2008 credit crunch might serve as a good exemplar. It was used in GM's Yukon/Escalade/Tahoe as well as some Chrysler, BMW, and Mercedes products if my memory serves me. It was their [6.0L] - [motor/generator] - [4-speed auto] - [motor] - driveshaft. My understanding is that it was a decent enough system; consumers just didn't care for them. I believe they're still used in urban buses.
That was the Two-Mode system; yes it was used by BMW and Chrysler (but not Mercedes as I recall) as well as GM, although only GM put it in a pickup truck. It is a compound power-split design, so at both motor/generator locations in that chain there is a mechanical power transmission path as well as the motor/generator.

The trucks were extremely expensive to build, and that's what killed them, because GM couldn't price them high enough to make up for the cost. GM spent their money on more advanced engines and transmissions for most vehicles, rather than depending on hybrids for efficiency, other than the plug-ins.

To understand the cost of this system, the transmission included two Remy HVH motor cores as well as roughly the components (other than the torque converter) of a four-speed automatic. Just the motor cores and associated controllers would cost about $30K (at a guess) if you bought them from Cascadia Motion today.

The same technology is still used in GM plug-in hybrids, and the Cadillac CT6 PHEV even has a longitudinal transmission of this design... but it's probably not up to truck-and-trailer duty.

Allison built the commercial version of the Two-Mode truck transmission, with stronger components and higher motor voltage (that's why there are 800 V HVH motor cores available). It is still available, and seems to have been most successful in buses, but is available for various medium to heavy trucks. It was called the H 40 EP / H 50 HP, and the line has recently been renamed eGen Flex. You wouldn't want this for a pickup - it weighs half a ton (literally) and is designed for high torque but very low speed engine input.

Rather than DIY building a hybrid, it would certainly be possible to just buy a Two-Mode hybrid truck (although I think the SUVs were more common) and upgrade the battery for more capability, but the Two-Mode trucks didn't have very high towing capacity (perhaps due to hybrid system cooling limitations, or perhaps due to the old 6.0 engine). In their stock form, the lack of battery capacity (typical of a normal hybrid, but far short of plug-in hybrid level) is what would distinguish these trucks from the intent of this project.
 

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Interestingly for Cybertruck the numbers vary from one source to the next. If I remember correctly Elon suggested something like 0.3, and some independent simulations reached as much as 0.48, while others were still leaning towards 0.3 due to some strange behaviors at speed.
That makes sense, because what Elon says is marketing fluff, not related to reality. There's no available real number for the CyberTruck, because it exists only as prototypes and Tesla won't share real information about it.
 

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If anyone is really interested in aerodynamic testing of road vehicles, they might be interested in the Laurel Hill Tunnel:

And now back to your regularly scheduled EV programming...
 

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Discussion Starter · #19 ·
I only got e-mail notification for the first wet-blanket reply so I hadn't even realized all this debate was going on. Very coincidentally, I am going camping at Laurel Hill State Park this weekend, It's just over an hour away. So I'll go shove the Silverado in the tube and have at it!

Most of this is above my paygrade, so simple it has to be.

But back to our regularly scheduled programming, I was planning on keeping this simple... Motor... Battery Bank... Control module at gas pedal... The motor to driveline adapter would have to be custom fabricated understood. So would the bracketry to hold the motor, I'm not about to even go looking for one.

The default battery bank charging method would be the engine alternator. There's a big aftermarket of alternators for the Duramax so single alternators in excess of 300 amps are out there, as well as dual alternator setups. Any alternative charging sources such as plug in or solar would have to be done on an auxiliary basis.

the connect/disconnect of the electric drive source would be the 2wd/4wd selector on the dash. The 4wd activates a servo on the front differential which engages the drive. 2wd would be electric motor disengaged.

The connect/disconnect of the truck's normal engine would remain at the transmission gearshift.. I think. I mean if it worked out that electric-only drive was usable, even for emergency, I know there would be some concern about putting the transmission in Neutral and going. I think that automatic transmissions have to have the engine running to lubricate but not positive about that.

Would be interested in hearing about potential sourcing so I could start working up a parts list and task list....
 

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Very coincidentally, I am going camping at Laurel Hill State Park this weekend, It's just over an hour away. So I'll go shove the Silverado in the tube and have at it!
:LOL: That would be excellent! Too bad they won't let you in; some real aerodynamic data for actual tug-and-trailer rigs would be interesting

The default battery bank charging method would be the engine alternator. There's a big aftermarket of alternators for the Duramax so single alternators in excess of 300 amps are out there, as well as dual alternator setups. Any alternative charging sources such as plug in or solar would have to be done on an auxiliary basis.

the connect/disconnect of the electric drive source would be the 2wd/4wd selector on the dash. The 4wd activates a servo on the front differential which engages the drive. 2wd would be electric motor disengaged.
The drive motor would be a better generator, and would operate at the right voltage for the battery - no big DC-to-DC converter required.

If you use an induction motor (rather than a permanent magnet AC motor) it will spin freely when not driving or generating, so there's no need for a mechanical disconnect system for it at all. That make it available for both regenerative braking and generation at low power when cruising (instead of needing another engine-mounted alternator).

The connect/disconnect of the truck's normal engine would remain at the transmission gearshift.. I think. I mean if it worked out that electric-only drive was usable, even for emergency, I know there would be some concern about putting the transmission in Neutral and going. I think that automatic transmissions have to have the engine running to lubricate but not positive about that.
Yes, automatics typically drive their internal oil pump from the input shaft, so if it (the engine) is not turning, there's no lubrication or cooling (and no way to engage any gear). External pumps are the usual solution for people who flat-tow (on all four wheels) automatic transmission vehicles behind their motorhomes, and some recent automatics have an electric pump so they can shut of the engine at idle and have it ready to go as soon as the engine restarts.

The easier solution for a typical 4X4 (truck style) is to shift the transfer case to neutral, which leaves all of the transmission entirely stopped. Some of those people towing vehicles behind motorhomes use 4X4 trucks and SUVs just to get this neutral feature.
 
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