# Is it even possible?



## 67BGTEV (Nov 1, 2013)

Assuming your 4 runner is awd, if you could somehow drive either front wheel or rear wheel powered by ICE, add an electric motor on the other drive, it should workout well. In this case, you may need to worry about ECU.

If it's a FWD, add a diff to the rearend and drive it with a AC motor, it may simplify and give you a trouble free solution. 



Sent from my ONEPLUS A6013 using Tapatalk


----------



## AZguy (Jul 6, 2018)

67BGTEV said:


> Assuming your 4 runner is awd, if you could somehow drive either front wheel or rear wheel powered by ICE, add an electric motor on the other drive, it should workout well. In this case, you may need to worry about ECU.
> 
> If it's a FWD, add a diff to the rearend and drive it with a AC motor, it may simplify and give you a trouble free solution.
> 
> ...


Yea it’s an awd. Its awd or the center diff locks into 4wd. If I was able to add power before the center diff it would go to all wheels when it’s not locked.


----------



## brian_ (Feb 7, 2017)

New people frequently propose this sort of setup, which is a plug-in hybrid. It is difficult to do properly, and even then it is only really useful in urban applications. Carrying a massive battery plus all of the controller and motor hardware for the small range extension just isn't worthwhile, and will increase fuel consumption due to the extra weight. Some people do this for regenerative braking, but that's typically not worthwhile in a highway application, either.

Sorry, but that's reality.


----------



## brian_ (Feb 7, 2017)

67BGTEV said:


> Assuming your 4 runner is awd, if you could somehow drive either front wheel or rear wheel powered by ICE, add an electric motor on the other drive, it should workout well.


That's the approach taken by various AWD hybrids, such as the Toyota RAV4 and Highlander, Honda Pilot and Acura MDX, Volvo XC90 T8, and Mitsubishi Outlander. The Outlander is even a plug-in. All of those are basically front-wheel-drive platforms.

The 4Runner has a traditional truck layout; it wouldn't adapt well to the scheme with one axle driven by the engine and the other driven electrically. It also has a very functional AWD system, so this scheme would sacrifice substantial capability.


----------



## AZguy (Jul 6, 2018)

brian_ said:


> New people frequently propose this sort of setup, which is a plug-in hybrid. It is difficult to do properly, and even then it is only really useful in urban applications. Carrying a massive battery plus all of the controller and motor hardware for the small range extension just isn't worthwhile, and will increase fuel consumption due to the extra weight. Some people do this for regenerative braking, but that's typically not worthwhile in a highway application, either.
> 
> Sorry, but that's reality.


Sucks to hear that but that’s the kind of information I wanted to ger before I jumped into some giant project if it didn’t have any chance of working out. Anything I could gain would be huge over a long trip, is there anything you guys can think of that could possible accomplish that or is trying to turn the 4Runner into any kind of hybrid a lost cause?


----------



## brian_ (Feb 7, 2017)

AZguy said:


> Anything I could gain would be huge over a long trip, is there anything you guys can think of that could possible accomplish that or is trying to turn the 4Runner into any kind of hybrid a lost cause?


One type of hybrid is the "mild hybrid", which uses a minimum of hardware, so it doesn't add too much weight or have many other consequences. The purpose is primarily to recover energy during braking (regenerative braking), to be used to help during acceleration and to reduce energy used to generate 12 volt electrical power. The alternator (and usually the starter motor) is replaced by a much more powerful (but still small by hybrid standards) motor/generator, and a battery... of much higher capacity and higher voltage than the normal starting battery, but of much smaller capacity and lower voltage than a typical hybrid battery. Like other hybrids, it normally supports engine stop-start operation (shutting the engine off when stopped in traffic and quickly restarting the engine when needed).

Mild hybrid systems have been used - and abandoned - by various auto manufacturers. They are currently featured in the Jeep Wrangler and in Ram pickup trucks, where they call it "eTorque" (because they use it as a motor to assist the engine at low speeds); this is a 48-volt system, belt-driven at least with the V8 engines, with a 12 to 16 hp motor and only half a kilowatt-hour of storage.

About that belt drive...

As mentioned earlier, mechanically connecting an electric motor to the powertrain - especially without packaging, cost, and efficiency problems - is a challenge. In addition, the motor can be smaller if it can always run at relatively high speed, meaning it is on the input side of the transmission, rather than the output.

There was a Chevrolet Silverado "Hybrid" which apparently nicely packaged a mild-hybrid-sized motor-generator in the transmission bell housing, along with the torque converter. There are more capable parallel hybrids in Europe which have a larger motor/generator in the transmission bell housing, using transmissions from ZF. Honda's original Integrated Motor Assist system packaged the motor-generator with the flywheel, again essentially in the transmission bell housing. This is mechanically a very nice way to go, but not practical to retrofit, and the motor-generator must run at crankshaft speed unless it has a dedicated planetary gearset.

An easy way out, used by the Ram eTorque and earlier GM systems, is the belt drive. Since the motor-generator is functionally replacing the alternator, mounting it in the same place but with a much higher capacity belt drive makes sense. It is even possible - although not necessarily easy - to do this as a custom modification.


The problem in this case is that in highway use, there's no fuel saving from stopping the engine when stopped in traffic, the fuel saving from generating only while braking is tiny, and regenerative braking is significant only in if you are doing a lot of engine braking while descending mountains. It might save you more while off-roading, but on the highway the Ram trucks only improve from 22 mpg to 23 mpg with eTorque. If I had millions of dollars to develop a system which would add $1500 to each vehicle to make a 5% improvement in fuel economy plus moderately improve driveability, I think a mild hybrid would make sense. To substantially improve the towing fuel consumption situation, I don't see it being feasible.


----------



## AZguy (Jul 6, 2018)

brian_ said:


> One type of hybrid is the "mild hybrid", which uses a minimum of hardware, so it doesn't add too much weight or have many other consequences. The purpose is primarily to recover energy during braking (regenerative braking), to be used to help during acceleration and to reduce energy used to generate 12 volt electrical power. The alternator (and usually the starter motor) is replaced by a much more powerful (but still small by hybrid standards) motor/generator, and a battery... of much higher capacity and higher voltage than the normal starting battery, but of much smaller capacity and lower voltage than a typical hybrid battery. Like other hybrids, it normally supports engine stop-start operation (shutting the engine off when stopped in traffic and quickly restarting the engine when needed).
> 
> Mild hybrid systems have been used - and abandoned - by various auto manufacturers. They are currently featured in the Jeep Wrangler and in Ram pickup trucks, where they call it "eTorque" (because they use it as a motor to assist the engine at low speeds); this is a 48-volt system, belt-driven at least with the V8 engines, with a 12 to 16 hp motor and only half a kilowatt-hour of storage.
> 
> ...


Thanks for all the info. Yea a gain of 1 mpg overall wouldn’t be worth the effort of building the system or worth the loss of space that equipment would take up. Sounds like making the 4Runner a hybrid just isn’t worth the effort.

The other possibility I was thinking about was powering the trailer axle. I love 5 mpg pulling the trailer and if I could power the trailer enough to even just offset its own weight I’d essentially be gaining 5 mpg on trips. I was thinking I’d have a lot more room since there isn’t really anything else under there and I could possible use a 4Runner rear axle and just connect the motor to the input flange on the rear axle, the worst cast if I ever get stranded way out because of a ring gear or something I could canabalize the rear end if needed in an emergency.


----------



## Jimbo69ny (Feb 13, 2018)

Sounds like you need to get the tow vehicle figured out. Go with an EV and you can copy what I did. 

Subscribe to my YouTube channel because I’ve done what your asking about. 

YouTube.com/jimbo69ny


----------



## remy_martian (Feb 4, 2019)

AZguy said:


> The other possibility I was thinking about was powering the trailer axle. I love 5 mpg pulling the trailer and if I could power the trailer enough to even just offset its own weight I’d essentially be gaining 5 mpg on trips.


No free lunch

You've moved the weight from the truck to the trailer. Now you need more plies in the trailer tires and to compound it you'll have more rolling resistance because of the battery weight on the trailer tires.

Since you were willing to spend a bucket of money on the problem, sell the trailer, buy an Airstream. The root of your problem is the weight of the trailer and the craptastic tires that come with it.


----------



## brian_ (Feb 7, 2017)

AZguy said:


> The other possibility I was thinking about was powering the trailer axle. I love 5 mpg pulling the trailer and if I could power the trailer enough to even just offset its own weight I’d essentially be gaining 5 mpg on trips.


Okay, but...



brian_ said:


> Carrying a massive battery plus all of the controller and motor hardware for the small range extension just isn't worthwhile, and will increase fuel consumption due to the extra weight.


This is still true, because...


remy_martian said:


> No free lunch
> 
> You've moved the weight from the truck to the trailer.



If you were going to add the hardware anyway, there is some appeal to putting it in the trailer:


AZguy said:


> I was thinking I’d have a lot more room since there isn’t really anything else under there...


Also, adding mass in a low position (as long as you keep in central in the trailer, not out at the ends) would make the trailer more stable. If the charge level is managed properly, the battery could also be used as a 

The drive force, and the drag of regenerative braking, would be where the weight and therefore traction is.



AZguy said:


> ... I could possible use a 4Runner rear axle and just connect the motor to the input flange on the rear axle, the worst cast if I ever get stranded way out because of a ring gear or something I could canabalize the rear end if needed in an emergency.


Yes, that's possible. This is the approach used by a company which was promoting this trailer-for-hybrid scheme for commercial tractor-trailer rigs: Hybrid Electric-Drive Trailer Tandem Being Developed. An indication of the real-world feasibility of this approach in commercial trucking is that this company (Hyliion) has apparently abandoned it and shifted to trying to sell hybrid upgrades for trucks. Two problems were probably that truck operators didn't want to invest money in complex trailers that they might not even own, and integration of the truck and trailer systems. The first one wouldn't apply to a personal RV rig.

From an article, an insight into how limited the benefits are of this system:


> According to Thomas Healy, founder and CEO of Hyliion, the hybrid propulsion system can deliver up to 15% in fuel savings in the optimum operating environment, which is rolling hilly terrain.
> 
> “The battery size, power density and chemistry, along with our electronic controller and battery management system, are optimized for short-duration, high-energy discharge and equally rapid charging over short distances,” Healy explained. “Obviously we do not want to add a lot of weight with a larger battery, so it’s designed for optimum performance on the rolling hills you find on Interstate highways in states like Pennsylvania, Virginia, West Virginia, etc.”
> 
> The ROI varies based on the amount of time spent in the optimum terrain, the total number of miles per year, and the amount of time the APU is used. In most cases, with 120,000 miles and regular use of the APU, the ROI will be between 18 and 24 months when installed on a new truck, he said.


That's 180,000 to 240,000 miles to pay back - more than the complete life of a typical personally-owned vehicle, and decades of typical RV travel. They didn't even consider a plug-in hybrid to replace fuel consumption with stored electrical energy.

Hyliion's web site does describe the system (now truck-based) well, and provides some insights into the required components and the complexity of managing the system well enough to have any benefit.


Now, about that axle...
Traditional automotive drive axles, such as that in the 4Runner, use a hypoid gear set (the ring and pinion). A hypoid set is right-angle gear set, but with the axes of the two shafts (pinion shaft and axle) not intersecting; the pinion shaft and therefore the propeller shaft are offset lower than the axle line. This has some packaging advantages and is both strong and quiet, but is inherently less efficient than an ordinary bevel gear set due to the sliding contact between the gear teeth. Since the trailer axle would be unpowered much of the time (as soon as the battery charge runs out in a plug-in scenario; most of the time on flat ground in the brake-and-assist for grades scenario), it would have a substantial drag cost.


----------



## AZguy (Jul 6, 2018)

So I was looking around again and saw this echarger system stuff. It’s essentially just what I was talking about except that’s adding the power through a belt system attached to the front of the crank vs the rear of the trans like I was talking about, 

https://www.enginelabs.com/news/sema-2016-e-charger-bolt-on-hybrid-system-draws-crowds/


Was this system proved a scam or something? Seems like an obvious answer but you guys had good points to why it wouldn’t work. His numbers sound crazy but the fact I haven’t seen it from anywhere else makes me skeptical. Plus all I can find is promo stuff and no actual testing or numbers on paper which give me a kinda scammy vibe.


----------



## remy_martian (Feb 4, 2019)

GM has/had Hybrids do this.

Yes, it works.

The numbers he picked were based on craptastic TRUCK mileage numbers...again no scam. IIRC, it takes a Silverado from 18 to 24 MPG, or so.

But this idea is nothing "amazing" or "new", either.


----------



## The_Sasquatch (Feb 11, 2018)

It's not a scam, it's a more powerful version of the mild hybrid system the new Ram trucks are using... The problem with this system is that it won't provide much if any fuel economy improvement at highway speeds. 


How aerodynamic is your trailer? How about the truck? If you handy enough to consider a hybrid build, you may be able to get a few mpg with aerodynamic improvements... I think there are aftermarket engine tunes for better economy too, I know a guy who tows trailers and switches ECU maps to something optimized exactly for cruise economy after he has the trailer up to speed and is facing a long straight stretch of road. He has to switch back if he brakes or gets to a hill, but it saves him enough to be worth it... I don't know if something like that is available for a 4runner.


----------



## AZguy (Jul 6, 2018)

The_Sasquatch said:


> It's not a scam, it's a more powerful version of the mild hybrid system the new Ram trucks are using... The problem with this system is that it won't provide much if any fuel economy improvement at highway speeds.
> 
> 
> How aerodynamic is your trailer? How about the truck? If you handy enough to consider a hybrid build, you may be able to get a few mpg with aerodynamic improvements... I think there are aftermarket engine tunes for better economy too, I know a guy who tows trailers and switches ECU maps to something optimized exactly for cruise economy after he has the trailer up to speed and is facing a long straight stretch of road. He has to switch back if he brakes or gets to a hill, but it saves him enough to be worth it... I don't know if something like that is available for a 4runner.


Yea I was going to work on the aero dynamics issue also. Right now the 4runnee is horrible as far as aerodynamics is concerned. Boxes on the roof, lifted some. Was planning on making a deflector for the roof rack and making an aluminum full underbody skid kit so the whole bottom will be flat. Not sure how big a difference this will make. Probably won’t have time before our next big trip in a week or so.

I know I probably sound like an idiot but how can a system like that not help at highway speed? I feel like an addition of a motor so that the engine doesn’t need to work as hard to maintain speed would be most beneficial at highway speed? I don’t want to gain power, just add mileage.

Thanks for the comments and help guys, I’m sure it can be a pain talking to some new guy who doesn’t know the basics but it’s really helping me out.


----------



## rmay635703 (Oct 23, 2008)

It’s a complex engineering problem to actually gain anything from what you propose.

There are some who reinforce the bumper and add a hitch to the Chevy Volt to tow

You can pick one of those up for $5000, test it out and see if it improves anything 

Without an OEM drivetrain in your contraption it’s unlikely to do much


----------



## AZguy (Jul 6, 2018)

I may just put a little time in and experiment with a set up. Even if it doesn’t work I’ll feel bette that I gave it a try and it’ll probably make more sense to me why it’s not going to work. 

This motor is near me and affordable would something like this work for the type of setup I’m talking about?

Thanks guys


----------



## rmay635703 (Oct 23, 2008)

It’s too small for your use case and would need multiple gears to span your speed range.

More gain just driving carefully with a scangage 

https://expeditionportal.com/forum/...-rave-about-mpg-4th-gen-4runner-v6-4x4.84581/

https://ecomodder.com/forum/showthread.php/08-toyota-4runner-aero-mods-14-better-fuel-37078.html


----------



## AZguy (Jul 6, 2018)

rmay635703 said:


> It’s too small for your use case and would need multiple gears to span your speed range.
> 
> More gain just driving carefully with a scangage
> 
> ...


I only need it to work at 65. We set the cruise control for 65 and leave it for all the long stretches, maybe it could gear it just for that speed and just engage it then. If I could gain some mpg on just the long stretches that would save us a ton over the whole trip.

We already drive as carefully as possible and stay at 65 on basically the entire trip on the highways but we off-road so have to make some sacrifices as far as aero dynamics.


----------



## Duncan (Dec 8, 2008)

Not sure how you are going to use that motor but it looks like a brushed DC motor and those motors do not like being driven with no current through the brushes - driving the motor with no current will quickly destroy the film on the commutator and then either the brushes or the com will wear out


----------



## AZguy (Jul 6, 2018)

Duncan said:


> Not sure how you are going to use that motor but it looks like a brushed DC motor and those motors do not like being driven with no current through the brushes - driving the motor with no current will quickly destroy the film on the commutator and then either the brushes or the com will wear out


Ok thanks, I’ll try and keep an eye out for something that will work better so I can try it out , waste some time and money then realize you guys were right all along and toss it haha


----------



## AZguy (Jul 6, 2018)

Duncan said:


> Not sure how you are going to use that motor but it looks like a brushed DC motor and those motors do not like being driven with no current through the brushes - driving the motor with no current will quickly destroy the film on the commutator and then either the brushes or the com will wear out


Seller says it’s brushless, if he’s correct would it be worth giving a shot?


----------



## Duncan (Dec 8, 2008)

AZguy said:


> Seller says it’s brushless, if he’s correct would it be worth giving a shot?


Brushless means that you will have no problem with the brushes!

But it does open another can of worms - brushless requires a more complex and less universal controller - have you got a suitable controller?


----------



## brian_ (Feb 7, 2017)

AZguy said:


> This motor is near me and affordable would something like this work for the type of setup I’m talking about?





AZguy said:


> Seller says it’s brushless, if he’s correct would it be worth giving a shot?


A brushless motor from Advanced DC? That seems very unlikely - did they ever make such a thing? The motor in the photos certainly looks like it has a commutator and brushes on the left-hand end.


----------

