# Exploring a possible Jeep conversion



## Duncan (Dec 8, 2008)

Southern Gorilla said:


> So is it feasible to make it run highway speeds, accelerate reasonably, and have enough range to leave the city limits... all on a blue-collar budget? I don't mind if it takes time to accumulate the parts. I don't mind using open-source bits to save cash. I'm even willing to sacrifice that lovely V-8 roar in favor of golf-cart silence. But not if that means I have to also sacrifice performance.


_have enough range to leave the city limits_
This is the critical factor - How many miles do you NEED


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## Southern Gorilla (Sep 21, 2013)

Duncan said:


> _have enough range to leave the city limits_
> This is the critical factor - How many miles do you NEED


I'm not sure I can answer that question accurately. I live in the Dallas-Ft. Worth metroplex. It's twenty-plus miles to my wife's mother's house. So I'd need to at least be able to make that round trip while running the lights and accessories. But the big gray area is that I'm building the Jeep to go four-wheeling as well. That means driving to a recreational area, playing in the dirt, and driving back. Even as large as the old Cherokee is I'm not sure it has enough room for a sufficient battery pack to provide that kind of range.

According to what I've read around here, regenerative braking would add 10-20% to the range. The Cherokee has a huge, flat roof-- would solar panels help?


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## glaurung (Nov 11, 2009)

Hi,
Jeep is easily converted. Bit pricey maybe.
Soliton1 controller, 11" motor and approx. 200v 200ah lithium batteries and you are good to go. 
When choosing batteries and chargers make sure to get parts that are easily replaced if needed later.Use voltages that are common.
regards, Harri


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## Southern Gorilla (Sep 21, 2013)

Well, I no longer have doubts about electric 4x4s.
http://www.bigfoot4x4.com/2012/1113_bf20.html

But I wish there were more updates on this system.
http://www.4x4-ev.com/

I absolutely love the wheel-mounted motor layout. Each motor could be individually controlled based on steering input so that each wheel spins at exactly the right speed for the radius of the turn. Perfect AWD. And wheels up in the air wouldn't cause a loss of traction since the remaining wheels would still have full power to them.

Of course, I don't have Bigfoot's budget. But that second system looks purely DIY. He's even building the motors from scratch. That's pretty sweet. Sounds doable. If I had plans to build from.


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## TEV (Nov 25, 2011)

Southern Gorilla said:


> Well, I no longer have doubts about electric 4x4s.
> http://www.bigfoot4x4.com/2012/1113_bf20.html
> 
> But I wish there were more updates on this system.
> ...


Just a hint : how many conversion are using this hub motor ?

Anyone converting is dreaming of those hub motors, unfortunate they are not available.

Welcome to the forum.


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## Southern Gorilla (Sep 21, 2013)

TEV said:


> Just a hint : how many conversion are using this hub motor ?
> 
> Anyone converting is dreaming of those hub motors, unfortunate they are not available.
> 
> Welcome to the forum.


Thanks for the welcome. Can't promise I'll be around very long. I tend to lose interest in things when something shiny crosses my view. Plus it's starting to look like a conversion that can meet my needs would be well out of my budget.

So why are hub motors scarce? They don't seem to be exceptionally complicated. Looks like anybody could wind one if they wanted.


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## TEV (Nov 25, 2011)

Southern Gorilla said:


> Thanks for the welcome. Can't promise I'll be around very long. I tend to lose interest in things when something shiny crosses my view. Plus it's starting to look like a conversion that can meet my needs would be well out of my budget.
> 
> So why are hub motors scarce? They don't seem to be exceptionally complicated. Looks like anybody could wind one if they wanted.


 http://www.diyelectriccar.com/forums/showthread.php/15-car-hub-motor-799-52336.html


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## Duncan (Dec 8, 2008)

Southern Gorilla said:


> So why are hub motors scarce? They don't seem to be exceptionally complicated. Looks like anybody could wind one if they wanted.


The short answer
Usable torque is roughly proportional to motor weight 
(oversimplifying a storm!)

So for increased torque you can
(1) Gear it down
(2) Get a bigger motor

(1) is a ton lighter, cheaper, better

Same reason all road vehicles use a gearbox to allow the motor (or engine) to turn at higher rpm's than the road wheels


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## Southern Gorilla (Sep 21, 2013)

Duncan said:


> The short answer
> Usable torque is roughly proportional to motor weight
> (oversimplifying a storm!)
> 
> ...


I saw that issue raised in the thread TEV linked above. Along with the objection that there is no electric motor sturdy enough to support a vehicle wheel.

Pardon me for saying so, but both objections are based in ignorance as there are very simple solutions to both problems.

The weight issue is readily resolved by using a full-floating spindle. This is exactly what you'll find on the front of every FWD, AWD, and 4WD vehicle I am aware of. Mount the wheel motor on the inboard side of the spindle and run a short shaft through to the wheel drive flange. The motor then sees 0% of the vehicle weight.

The torque issue is readily resolved by using a planetary hub as found on construction equipment, farm equipment, forklifts, and monster trucks. That gives you a minimum of about 4:1 reduction. Reduction in excess of 50:1 is easily done. I'm not sure if there are off-the-shelf units with the right physical dimensions for small EVs. But since planetary hubs are also used on some bicycles it seems likely that a bit of research would turn up something. Failing that, a skilled DIYer could probably figure a way to use the planetary gears from an automatic transmission.

Of course, if you are building a lightweight EV you'll want to keep the unsprung weight down. I saw a comment in the thread TEV linked where the poster said unsprung weight is a non-issue, but this is not entirely correct. As unsprung weight increases relative to sprung weight the suspension becomes increasingly irrelevant. If unsprung weight exceeds sprung weight you might as well bolt the axles directly to the frame. Anyhow, a heavy wheel-mount motor combined with a planetary hub would likely be too heavy for an electric Miata or similar "sporty" car. In such a case I would definitely mount the motor and reduction unit inboard and use a short driveshaft to the wheel. That also helps the "polar moment of inertia", which is important in sporty cars.

This wouldn't be the cheapest way to build an all-wheel drive EV. But from a performance standpoint it would be the best. Having control over each wheel individually allows you to spin the inside wheels slower and the outside wheels faster in a curve. It allows you to reduce power to a wheel with less traction and send that power to the wheels that still have traction. All the things engineers struggle to accomplish with mechanical systems become almost trivial with electric power. Honestly, that's the main reason I'm considering this electric conversion. To accomplish anything close to this with traditional power is difficult and expensive.

Sorry for the long-winded post. I get that way when I get excited about an idea.


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## Duncan (Dec 8, 2008)

Southern Gorilla said:


> Pardon me for saying so, but both objections are based in ignorance as there are very simple solutions to both problems.


There are always simple solutions - for the simple minded
So we now replace one motor with four
and one gearbox with four

And we still have four drive-shafts
and four controllers

Sound like four times the cost - for very little benefit!

The only application I have seen where that made sense was on the NASA lunar rover

but both objections are based in ignorance

The ignorance is somewhere else - find a mirror


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## Southern Gorilla (Sep 21, 2013)

Duncan said:


> There are always simple solutions - for the simple minded
> So we now replace one motor with four
> and one gearbox with four
> 
> ...


 There's no need for an angry tirade. "Ignorance" is not a pejorative term. "Argument from ignorance" is a legitimate logical fallacy wherein a person makes an argument based on incomplete or incorrect information. So the people in the above-linked thread who said hub motors could not work because they could not handle the weight were most definitely ignorant of the fact that full-floating axles resolve the issue. And people who said hub motors could not work because of the lack of torque multiplication were definitely ignorant of the existence of planetary hubs.



> Sound like four times the cost


 Highly unlikely. A single motor capable of producing 500 lb-ft of torque would be massive and expensive. I am quite confident that four 125 lb-ft motors would not cost four times as much as that single 500 lb-ft motor.



> and one gearbox with four


 This is a gross misunderstanding of the systems involved. A four-motor system would actually replace four gearboxes, not one. It would replace the transmission, the transfer case, and the front and rear differentials. The weight savings would be massive. 



> There are always simple solutions - for the simple minded


 Are you saying that only idiots look for simple solutions? Truly intelligent people try to make things as complicated as they can? The only person I've ever heard of who might agree with that was a gentleman by the name of Rube Goldberg.



> The only application I have seen where that made sense was on the NASA lunar rover


 Did you even bother reading that this thread is about a Jeep? That's a 4-wheel drive vehicle intended to be used on rough terrain. Not entirely unlike the lunar rover. So just maybe hub motors might make sense here.



> The ignorance is somewhere else - find a mirror


 I readily acknowledge my ignorance. That's why I join forums, to talk with those less ignorant than myself so I can shed some of my ignorance in favor of knowledge.


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## flynn23 (Jul 2, 2013)

Southern Gorilla said:


> This is a gross misunderstanding of the systems involved. A four-motor system would actually replace four gearboxes, not one. It would replace the transmission, the transfer case, and the front and rear differentials. The weight savings would be massive.


I'm looking to do a very similar conversion (1993 Jeep Cherokee) so this piqued my interest. 

And I do agree that having 4 hub motors would give you ultimate control, but why go that route when you've already got proven mechanical systems that do the same thing (variable transfer cases, locking differentials, etc)? 

The weight would probably be a wash out in the end and the complexity of controlling 4 motors and associated power to each instead of one motor and relying on electro-mechanical drive train seems an easier solution. Let's not even get into the bigger off road problem of failure points.

Plus getting a 500ftlb motor isn't really a problem. Finding enough Ah on board the vehicle to use it for more than 10 minutes would be the bigger problem.


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## Southern Gorilla (Sep 21, 2013)

flynn23 said:


> And I do agree that having 4 hub motors would give you ultimate control, but why go that route when you've already got proven mechanical systems that do the same thing (variable transfer cases, locking differentials, etc)?


 For my specific application the axles need to be upgraded. So there's significant money. And the lockers for the new axles are around $1,000 each as I recall. The cost of upgrading one axle is almost equal to what I've seen a couple junkyard EV conversions cost.

But I'm still not convinced I want to convert my Jeep. Much less go to the trouble of trying something out on the fringe like a 4-motor system.


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## flynn23 (Jul 2, 2013)

Southern Gorilla said:


> For my specific application the axles need to be upgraded. So there's significant money. And the lockers for the new axles are around $1,000 each as I recall. The cost of upgrading one axle is almost equal to what I've seen a couple junkyard EV conversions cost.
> 
> But I'm still not convinced I want to convert my Jeep. Much less go to the trouble of trying something out on the fringe like a 4-motor system.


You can do all of that on the cheap as well. Decent axles can be found in junkyards. Diffs can be welded to lock them. Or you can get manual hub lockers for $150/ea. My point being that a 4 motor system would be an supreme engineering challenge whereas using the existing tricks of the trade for a mechanized powertrain would be quick and easy. 

Given the cost of a decent crate engine these days, you're in the same boat if you go EV. You're likely to upgrade the suspension and powertrain anyways, so that's not gonna be ex budget. What you'll save in things like air flow, programming, and protecting the spinning bits for an ICE based project, you can redeploy for EV bits. It was one of my justifications for going EV with my Jeep. I'd spend just as much money upgrading it if I went ICE. At least this way, I don't have to pay for shitty gas mileage.


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## hmincr (Jan 20, 2012)

Isn't Ripperton the one doing a hub motor car conversion ?? Might try looking for his thread to get some ideas. Here ya go, Gorilla. Yes, it's a small car, but, the man has ideas, and is rewinding the motors.

http://www.diyelectriccar.com/forums/showthread.php/mira-inboard-hub-motors-82349.html


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## Southern Gorilla (Sep 21, 2013)

flynn23 said:


> You can do all of that on the cheap as well. Decent axles can be found in junkyards. Diffs can be welded to lock them. Or you can get manual hub lockers for $150/ea. My point being that a 4 motor system would be an supreme engineering challenge whereas using the existing tricks of the trade for a mechanized powertrain would be quick and easy.
> 
> Given the cost of a decent crate engine these days, you're in the same boat if you go EV. You're likely to upgrade the suspension and powertrain anyways, so that's not gonna be ex budget. What you'll save in things like air flow, programming, and protecting the spinning bits for an ICE based project, you can redeploy for EV bits. It was one of my justifications for going EV with my Jeep. I'd spend just as much money upgrading it if I went ICE. At least this way, I don't have to pay for shitty gas mileage.


 I plan on using some junkyard bits, if I can find them. But the planned axles are custom hybrids to handle the weight of the tires. Welded diffs are useless for a street-driven truck. My plans aren't about being the cheapest possible build. I have certain performance criteria. Meeting those goals is mechanically possible, but not necessarily cheap.

There is a possible middle ground here. A 2-motor system would possibly be cheaper than a 4-motor. That would still require the upgraded axles. But then I get the gear reduction of the differential and the ability to mount the motors in a more protected area.



hmincr said:


> Isn't Ripperton the one doing a hub motor car conversion ?? Might try looking for his thread to get some ideas. Here ya go, Gorilla. Yes, it's a small car, but, the man has ideas, and is rewinding the motors.


Small car, big Jeep... it's just a matter of scale. That's a nice build. And doesn't seem very expensive at all. I just don't understand how he expects the motors to self-correct for the different wheel speeds in turns. The outer wheel in a turn has more load on it because of lateral weight transfer. That means the outer wheel will try to slow in a turn. Which is exactly the opposite of what you want. I did take not of the comment that mentioned using pots on the steering to compensate for this. Never knew the solution could be that simple. I guess the pots fine tune the signal from the throttle. I'll have to look into that further.


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## Tesseract (Sep 27, 2008)

Southern Gorilla said:


> ... I just don't understand how he expects the motors to self-correct for the different wheel speeds in turns. ...


Differences in turning radius, tire diameter, etc., are automatically compensated for by controlling motor torque, not speed.


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## Caps18 (Jun 8, 2008)

My second choice of donor vehicle was a Jeep Wrangler. However, I'm afraid that it would be a real challenge to convert it correctly. It isn't a typical vehicle to convert. Maybe if you had some more experience with converting cars, then the chances of a successful conversion would be more likely. I'm not saying you couldn't do it, just that I wouldn't know all the different specs that you would need for the parts, and mounting the parts so if you roll over, they would still work.

But, it would be cool.


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## Southern Gorilla (Sep 21, 2013)

Tesseract said:


> Differences in turning radius, tire diameter, etc., are automatically compensated for by controlling motor torque, not speed.


This is where my ignorance shines through. I don't see how a motor can automatically speed up when a wheel changes direction. In any curve all four wheels will be traveling at different speeds. How would each of the controllers know how to adjust each motor correctly? Somebody please explain this phenomenon to me.


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## Overlander23 (Jun 15, 2009)

Glaurung and I have both converted Rovers... his a Range Rover Classic, and in my case a short-wheelbase '71 Series IIA.

Mine, in fact, uses an 11" DC Kostov motor, 64 LiFEPO4 (205 volts nominal), and a Soliton-1. It also weighs much less than 4000 lbs after conversion (it was about 3100 lbs before the conversion) but still has the aerodynamic properties of a small shed.

It's quick and has a range of between 75-90 miles, but while it will do at least 70mph, I've never driven very far at that speed. So, I can't say that it would do 75 miles at 65 mph, for instance... I don't know, I don't remember how much amperage I was pulling at that speed.

It cost me about $25k for the conversion... with me doing all the work and fabrication. If you consider that a blue-collar budget, then have at it. $11,500 of that was batteries alone.


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## Southern Gorilla (Sep 21, 2013)

Overlander23 said:


> It cost me about $25k for the conversion... with me doing all the work and fabrication. If you consider that a blue-collar budget, then have at it. $11,500 of that was batteries alone.


Eek! That is definitely not blue-collar. At least not my shade of blue. I could do an amazing gas engine for half that. Even a monstrous diesel would be far cheaper.


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