# Electric 6x6 ATV Conversion



## Nick (Mar 11, 2015)

Hey everyone! My name is Nick, and I'm a senior in high school. Currently I'm enrolled in an engineering class called Project Lead the Way along with my friend, Ethan. For years we've dreamed of creating this electric amphibious vehicle. A few weeks ago we went to a local forklift company and told them about our project, and they gifted us two motors! However, this is where we're stuck at now. We can't figure out what to use as speed controllers and the local places seem to only deal with motor repair. I believe this forum is the perfect source of information and guidance on our adventure. This is what we have:

*Specs*
Vehicle: Max IV 6x6 amphibious skid-steer atv
Motors (2): Iskra 3 phase AC AMT7130 about 5.3 hp & 120 lb. torque each. Electronic brakes.
Speed control: ? Something variable speed drive.
Batteries: Linked 12V's.

*Idea:* One motor for each side of the drivetrain. For controlling the vehicle, we want to utilize the standard sticks. If one stick is pushed forward, that side of wheels will go forward. If it's pulled back, the wheels will go in reverse. Thus we will have a high-precision vehicle with counter-rotation.

*Questions:*
1. What should we use for a speed controller? We need something variable that can go from instant forward to reverse.
2. Are these motors uncommon? I can't find much information on them at all.
3. Are we forgetting anything else to get this prototype built?

Thank you for reading through this post. I hope we can gain valuable information to get this project built as soon as we can. Once we have the parts figured out, we're going to start fabricating and assembling the machine.



















































https://www.youtube.com/watch?v=3cWnpzG9F20

http://www.muddoxinternational.com/mxi/products/max/max-iv-efi-6x6/


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## arklan (Dec 10, 2012)

what do u have other than 2 ac motors?


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## Nick (Mar 11, 2015)

arklan said:


> what do u have other than 2 ac motors?


That's all we have right now, we were hoping the forum could point us in the right direction for variable speed controllers.


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## arklan (Dec 10, 2012)

ok so im gonna throw some information at u
im no expert(tm)

motors and motor controllers r 2 sides of a coin.. with ac the motor is cheap and the controller (vfd) is expensive
with dc they r about the same

those ac motors u have are in the realm of possibility of working
but to be realistic, take them back and get a couple of dc motors or your gonna regret it

how much money do u have as a budget for this?
series wound dc motors should be quite easy to get a hold of from the forklift place, aswell a dc motor controller from the same forklift place

to run 2 motors youll need 2 controllers and u can connect the pot boxes to the 2 sticks you mentioned
the pot boxes are the 'throttle pedals' from the forklift, id also get a contactor or 2 from the forklift so that u can turn the power on and off with a key

batteries r gonna be the killer, you can probably get some from the forklift place aswell but theyll probably be stuffed so u wouldnt want to be paying too much for them. to start with youd want to go with lead acids because they r about a 5th of the price but they r 3 times heavier so you wont be breaking any records

another route u could go would be to look in to the transmission from a bobcat (aka skid steer loader). they use the 2 sticks you mentioned and use a fluid coupling to control torque transfer from either the left or right driveshafts
this way youd need 1 motor and 1 controller but i wouldnt attempt this unless you had access to someone with experience in mechanics and hydraulics

there is a lot of work to be done to make this work outside of the electrical aswell, like how u transfer the driving power to 3 wheels on 1 side eg; chain, while also having each wheel have suspension.
and if u also plan to take it in to the water youll need to find a way to stop the water from getting in, sealed bearings can only get u so far.

also if u drive this on road/tarmac/asphalt it will bounce around and do all kinds of fun things when u try to steer

id be sticking to the single motor with the front wheels turning to steer rather than having it as a skid steer, u guys r going in to the deep end


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## Nick (Mar 11, 2015)

Thanks for the information. I'm a bit confused on why I should take the AC motors back and get DC? We were looking for speed controler ideas because we don't have a clue where to start. Is there a specific vfd model we should look into? For batteries we're going to use multiple car batteries to start. Budget is probably around $3,000 not counting our motors or the vehicle.

I'm not sure I was clear in my first post on the vehicle. We aren't creating the whole thing, just converting it to electric. Traditionally it has a skid-steer transmission belt driven from the engine, like a snowmobile. Then the tranny has a sprocket on each side, with a chain drive to the axles. They're solid and don't have suspension. 

We're taking out the engine and tranny, and mounting a motor on each side, chain-driving the axles. Each motor will essentially be a separate drive train. What we need now is a vfd speed controller (2) and then a way to control it on the sticks. We want to counter rotate, not have to "shift" the motors in reverse. Drive it like a hydraulic pump. I hope this makes more sense.


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## major (Apr 4, 2008)

Those appear to be nice low voltage AC induction motors. A Curtis 1238 controller could work. It would have to be tuned to the motor and setup to accept the motor feedback (encoder type). This might be more than you can do. First off, it requires a programmer pendant or PC software package (read about $800 but may be rented). And an applications engineer may be needed. Best case, send a motor to the dealer and have them program the controller for you. I believe Curtis can be set for master slave operation. Or use the VCL for CAN control.

The other possibility is to pursue the OEM controllers from the fork lift. That might be the ticket.

I think you would be more pleased with the operation of the AC drives over DC, if you can get them working properly. DC would be simpler. But series DC motors have an infinite no load speed so need overspeed cutoff circuits in case of chain loss. AC or DC SepEx or DCPM have defined no load speeds. You might look into DC SepEx from golf carts. I think you'd be in the power ball park. 

Looks like an interesting project. Good luck. There have been a couple of these done here, see member JRP3.

Probably should have posted in the non-road going vehicle sub forum. Perhaps a mod/admin can move the thread there.

major


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## Woodsmith (Jun 5, 2008)

major said:


> Probably should have posted in the non-road going vehicle sub forum. Perhaps a mod/admin can move the thread there.
> 
> major


Done that for you.


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## Duncan (Dec 8, 2008)

Hi Nick
You got the motors from a local forklift place?
Could you go back and ask about controllers for them?
Even if you have to buy new they could be a good bet

We don't normally use the controllers out of forklifts because we tend to up-volt and up-speed for car use
Not as important in your machine


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## Nick (Mar 11, 2015)

Thanks for all the information guys! I do know JRP3 off the amphibious atv forum. The forklift place doesn't know anything about controllers as they just do mechanical repair. I've read through the suggestions and decided to look into Curtis. Today during class I called their New York headquarters and got ahold of an engineer. We talked about the project and he has controllers that will work for us. The only thing stopping the decision is not knowing what amount of current our motors have. He was a really nice guy and even mentioned a possible sponsorship! 

I called Iskra and they don't speak English. So I decided to email them asking about the current but have yet to get a reply. Is there another way to figure it out? Thanks for all your help, I really appreciate it.


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## arklan (Dec 10, 2012)

the name plate of the motor has 15v 4kw
4000/15 =266amps

seems a bit off but no reason it couldnt be right


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## Nick (Mar 11, 2015)

arklan said:


> the name plate of the motor has 15v 4kw
> 4000/15 =266amps
> 
> seems a bit off but no reason it couldnt be right


On the tag it says "DC truck voltage: 24V"
So maybe it's 167 amps?

The equation is reliant that I'm drawing a power factor of 1, which I'm sure I'm really doing more like .85? Theoretically the absolute max amps I'm pulling is 167, but more around 113 with the power factor involved. This should mean the Curtis 1232E should work great.


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## major (Apr 4, 2008)

Nick said:


> On the tag it says "DC truck voltage: 24V"
> So maybe it's 167 amps?
> 
> The equation is reliant that I'm drawing a power factor of 1, which I'm sure I'm really doing more like .85? Theoretically the absolute max amps I'm pulling is 167, but more around 113 with the power factor involved. This should mean the Curtis 1232E should work great.


Not so quick. The phase voltage to the motor is 15VAC (rms). So figure the phase current using the 3 phase power equation with the .85PF. Now that would be the S2 60 minute rating for the motor. The control spec current is usually a current limit (AC phase rms). So that controller spec current should be on the order of 3 times the motor S2 rated current. I'd go with the 500A Curtis and good for 24, 36 or 48V to give you room to grow, if needed.

Ps. Would not involving the power factor make the current higher, not lower? 4000W would need 4700VA at .85PF, right?


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## Nick (Mar 11, 2015)

I'm really confused now. Is my motor 15V or 24V? What voltage do my batteries need to be? What amps do you believe this motor puts out? I'm sorry I don't quite understand all of this yet.


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## major (Apr 4, 2008)

Nick said:


> I'm really confused now. Is my motor 15V or 24V? What voltage do my batteries need to be? What amps do you believe this motor puts out? I'm sorry I don't quite understand all of this yet.


Hi Nick,

Sometimes I get a burr in my shorts when students come here and ask for help. Seems like they want someone else to do their homework or look for a substitute teacher. And that is not my purpose here. But I don't get that sense from you. But part of this hobby is the doing and learning. So I try not to hand you a canned answer.

Here's a reference: http://www.diyelectriccar.com/forums/showpost.php?p=376274&postcount=9 



major said:


> P = √3 * U * Irms * cosΘ
> 
> That is power in a 3-phase sinusoidal system. P in Watts, U is line to line RMS voltage, Irms is RMS phase current and cosΘ is power factor.
> 
> ...


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## Nick (Mar 11, 2015)

major said:


> Hi Nick,
> Sometimes I get a burr in my shorts when students come here and ask for help. Seems like they want someone else to do their homework or look for a substitute teacher. And that is not my purpose here. But I don't get that sense from you. But part of this hobby is the doing and learning. So I try not to hand you a canned answer.


Thank you for all the help! I can imagine students coming here and trying to get forum members to do everything for them. All of the electronics have been over my head and I'm slowly wrapping my head around all the concepts. The mechanical aspect is easy for me as I've restored some of the vintage 6x6's and a Willys Jeep. Electronics are new and have a learning curve.

I have a fantastic update. Today Ethan and I called the engineer from Curtis Instruments I talked to last week. We couldn't previously decide on a speed controller until I knew the amps of the motors. After doing some equations and getting a dyno chart from the manufacturer, we found out they have 400 amps and 45 ft lb of torque. We're going with a 1236E controller. Our max current is 400 so the engineer recommended the controller with a max current of 400, but I feel we should go to the 500 for that extra room to grow (the extra cost is minor). It's the 1236E-45XX. We're getting their 840 gauges to monitor the systems, battery, etc. Lastly the engineer told me to get the 1314 programming kit. What exactly goes on with programming the speed controller for the motors? 

It sounds like we're going to be ready to go for getting the build started. We're so very grateful for Curtis' support and information, we would be lost without them.


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## major (Apr 4, 2008)

Nick said:


> Lastly the engineer told me to get the 1314 programming kit. What exactly goes on with programming the speed controller for the motors?
> 
> It sounds like we're going to be ready to go for getting the build started. We're so very grateful for Curtis' support and information, we would be lost without them.


Bit bit premature to be thanking Curtis don't you think? They're making a sale. You need to ask them about programming. And, get a commitment from them for assistance in tuning the controller to the motor including the feedback device (encoder). Best case is to send them a motor and have them tune it. Or maybe walk you through it in real time via skype or something.


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## Nick (Mar 11, 2015)

major said:


> Bit bit premature to be thanking Curtis don't you think? They're making a sale. You need to ask them about programming. And, get a commitment from them for assistance in tuning the controller to the motor including the feedback device (encoder). Best case is to send them a motor and have them tune it. Or maybe walk you through it in real time via skype or something.


No I don't. They provided us with a full sponsorship for needed products and programming/technical support. We're excited to say the least!


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## major (Apr 4, 2008)

Nick said:


> No I don't. They provided us with a full sponsorship for needed products and programming/technical support. We're excited to say the least!


Good for you  I have never seen them near that helpful in the past.


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