# Newbie question: 2WD to 4WD via electric?



## Aim4gold (Mar 19, 2008)

Can it be done – yes. Anything is possible

A full size truck in 4x4 will have very limited distance.


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## TheSGC (Nov 15, 2007)

A lot of work would be involved with a new drive system for the rear end. I don't think it would really be worth it as not only would it involve more desiging, it would decrease range considerably. 

But yes, it can be done. I don't know of anyone who has done it, but check out the trucks on evalbum.com and see what is there.


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## trasko (Apr 3, 2008)

Hmm, thanks for the replies. Evalbum.com is great! Nice to see a centralized location for pictures/descriptions of people's projects. 

I perused the 3 major full-size truck manufacturers (ford, chevy, dodge) and didn't find anyone using a full-size truck. I also used google to search the site for anyone who has converted from 2wd to 4wd using electric assist. Nada.

I see that all my searches came up empty because no one seems to be doing this. 

Just to be clear, the idea was not to convert from ICE to pure electric. The thought was only to ADD in a relatively small electric system to drive the front wheels on-demand. I imagined it would have a smaller bank of batteries than most setups here and regenerative braking would provide a great deal of the charge (given that the ICE will be providing the initial energy to get the truck moving). 

Almost all of the time a vehicle just needs 2wd to move, so during general use the system would just be in state of augmenting (however minorly) the standard drive-system with recaptured energy from braking.

The time when it would really shine would be in situations where 4wd is needed for traction. With a built-in traction control system that would actuate the front wheels on demand (or just a dumb switch for that matter), the actual time the wheels would be driven should be pretty low. Also, the electricly-driven wheels won't be pulling the whole truck themselves -- they will almost always be augmenting the standard ICE RWD setup.

Perhaps this is also just totally out of scope for this site since it isn't an EV conversion... I appreciate the pointers.

~trasko


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## 3dplane (Feb 27, 2008)

Hey trasko! If I was approaching your plan I would start with a 4wd truck because the drive line is already there.Then remove the front drive shaft from the transfer case going to the front diff and mount the electric motor there.However experience with GM trucks tells me you can bearly slip your fingers around the front shaft due to it being so close to the trans.and just lack of room in that area.Maybe other makes are more forgiving I have no experience there.I understand your idea though and i believe if someone really wants to make it happen there are many ways to do it.Good luck!Barna.


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## HIDriver (Apr 1, 2008)

I was kicking that idea around with my 4runner. go-ev has an EMIS system that would go in between the transmission and the differential. I thought the shaft diameter was too small on the CE side of the motor and I think there's a guy showing some pictures of the motor shaft starting to shear when he noticed vibration. go-ev is redesigning the motor and supposedly will support pre-1996 vehicles. Supposed to come out in May. As far as the 4runner...not too much room even for the 7" motor. Also, not sure where to put the electric motor mounts. I was actually invisioning NEV mode with the front diff and then highway mode with the ICE. Sort of a home brew hybrid.


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## trasko (Apr 3, 2008)

Hmm so it sounds like using the standard 4wd components and modifying from there is the way to go... I was hoping (wondering, really) if there were "in-wheel" or similar kits in which there would be a single motor per wheel which would allow (in my theory) to get rid of all the power distribution components up front and do all the controlling by electronics.

Anyway, this has been very helpful and I found the referenced sites really great. The EMIS system sounds promising (my truck only gets 10-11mpg), however I have to wonder the kind of loads it can handle given that a full-size truck getting < 10mpg (as their website suggests is the target market) is probably going to be moving around a LOT of mass.


(and for reference, my truck is an '89 Ford F250HD)

Thanks for the help.


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## AmpEater (Mar 10, 2008)

Brushless wheel motors would be the ideal solution. You'd get a package that could mount in place of a standard wheel, yet provide both additional traction and efficient regenerative braking independent from the ICE drivetrain. 

There have been prototypes, a picture of an example here. But as far as you or I are concerned they don't yet exist. The largest commercially available are for bicycles or scooters. Perhaps in a few years, the technology is there, just not the production.


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## JRP3 (Mar 7, 2008)

Typically regen does not give you all that much usable energy, adding up to only a few more miles in stop and go, even fewer in highway miles. Also to do regen you can't use the inexpensive brushed DC setup. What you are trying to do is going to cost you much more than you'll ever get back I'm afraid. A smaller lighter truck would be better, and you'd want to put the motor inline with the rear drive shaft like the EMIS system.


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## AmpEater (Mar 10, 2008)

JRP3 said:


> Typically regen does not give you all that much usable energy, adding up to only a few more miles in stop and go, even fewer in highway miles. Also to do regen you can't use the inexpensive brushed DC setup. What you are trying to do is going to cost you much more than you'll ever get back I'm afraid. A smaller lighter truck would be better, and you'd want to put the motor inline with the rear drive shaft like the EMIS system.


When your regen energy comes from the battery pack, I agree, the return in usable energy will be a small percentage of the original amount expended. However, if you are capturing energy that originated from the ICE the amount captured might be several times the total battery storage you have on board. You are using the battery as a temporary resevoir of "recycled" energy destined to be wasted before you sucked it back in. The addition of the motor/battery provides other benefits, like the ability to eliminate idling. 

There is no reason you cannot have a hybrid with two independent drivetrains. It is known as a "road coupled hybrid".


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## Dennis (Feb 25, 2008)

> Typically regen does not give you all that much usable energy, adding up to only a few more miles in stop and go, even fewer in highway miles. Also to do regen you can't use the inexpensive brushed DC setup. What you are trying to do is going to cost you much more than you'll ever get back I'm afraid. A smaller lighter truck would be better, and you'd want to put the motor inline with the rear drive shaft like the EMIS system.


Actually a shunt wound and permanent magnet brushed DC motors can be used for regen. The only tough motor to get any regen from is a series-wound motor...


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## JRP3 (Mar 7, 2008)

I'm not sure what you mean. Regardless of what motivates the vehicle, the energy required to stop it will be the same, and that's your potential for regen. Percentage doesn't matter, only the distance in motive power regained from braking. I'm not talking about the other benefits of a hybrid drive, just the regen aspect. I agree it is possible and that there are benefits, just not sure if there will be any cost benefit in this situation.


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## trasko (Apr 3, 2008)

JRP3 said:


> I'm not sure what you mean. Regardless of what motivates the vehicle, the energy required to stop it will be the same, and that's your potential for regen. Percentage doesn't matter, only the distance in motive power regained from braking. I'm not talking about the other benefits of a hybrid drive, just the regen aspect. I agree it is possible and that there are benefits, just not sure if there will be any cost benefit in this situation.


Hmm, yes the thought that the regen system is different because the sole power-plant is an ICE isn't true -- it is the same (it still seems somehow different, but I can't see how). 

The line-of-thought started from wanting the benefit of 4WD (which, in my case, would only be needed in a once-a-week time period for perhaps 5 to 10 minutes at a pop). I thought that perhaps small, per-wheel motors and relatively small battery bank could provide this. Then come the side-projects: electronic traction control, plug-in charging of batteries so that around town the batteries could augment the ICE to improve effeciency as well as regen braking to further improve efficiency. I would love to improve the mileage of that big truck, but the primary goal is 4wd with everything else being secondary.

I will keep EMIS in mind, however given that my primary goal is to have 4WD and EMIS would require that I already have the 4WD running gear... well I'd just be adding electric for the sake of adding electric rather than to get me 4WD. I'd like to go electric sometime, but as has been stated before, a full-size truck is not what you want to use.


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## JRP3 (Mar 7, 2008)

Dennis said:


> Actually a shunt wound and permanent magnet brushed DC motors can be used for regen. The only tough motor to get any regen from is a series-wound motor...


Right, which is why I said "you can't use the inexpensive brushed DC setup."
Shunt and PM motors are typically more expensive and use more expensive controllers. Also, I thought PM motors were brushless?


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## Dennis (Feb 25, 2008)

> Also, I thought PM motors were brushless.


Tear open a cordless drill to see a brushed permanent magnet motor. Or you can go to any motor manufacture site and they will have brushed DC motors up to about 1.5 horespower, maybe a bit more.


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## Gtefend (11 mo ago)

trasko said:


> So I have spent a lot of time surfing around and have found essentially nothing on this... I am wondering how feasible -- given currently-used technology -- to convert a full-size 2WD truck to 4WD utilizing electric motors.
> 
> Has anyone done this? I welcome any pointers in the right direction.
> 
> Sorry for busting right out with a question as my first post, but a lot of my searches ended up here so I figured I would ask the experts


 I was thinking same think but by motors mounted front wheels only 
turn them on when you want four wheel drive 
Seems feasible and cool


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