# I'm interested in building a electric ATV.



## Functional Artist (Aug 8, 2016)

Jonkoehn said:


> I work on a farm and our gas powerd ATV's are high in maintenance.
> I thought it would be a good idea to convert one of our old suzuki ozark into a all electric vehicle.
> 
> I was thinking of using a me1003 motor, directly connected to the differential drive line. (I already have the motor so it makes sense to use it) a alltrax SR-48400 controller and a 10s2p nissan leaf battery pack( 36v 120amp )
> ...


 
Howdy & welcome,

You say, "I was thinking of using a me1003 motor, directly connected to the differential drive line." 

...directly connected to the differential drive line?

What do you mean?

...face mounted?

...with a chain?


3:1 ratio is a bit stiff & 22" tires have a lot of rolling resistance

...but, 10 mph should be doable


I put a motor like that on a Dingo go cart with bigger tires, a few years back

https://www.youtube.com/watch?v=AV0BQPm5JFo&index=13&list=PLoL6eIYWPO_ldEXj0hJX9nWGrLI8KmC7q

I ran it @ 36V also, it moved right along

the biggest drawback was the weight of the batteries

...I used (3) 12V 35AH SLA batteries (~20 lbs. ea.)

...it was so heavy In the back that the steering was more like a suggestion than a command

That motor, controller & battery pack is now on El Moto my electric motorcycle conversion

https://www.youtube.com/watch?v=NdwRuXyiqms

...a much better combination IMHO

When I ran it 

[email protected] 36V the top speed was ~25mph

...now @ 48V, top speed seems to be ~35 mph

It has a 5.4:1 ratio (10 tooth drive gear & a 54 tooth driven gear)


* Switching to Lithium in the spring


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## Jonkoehn (Jan 4, 2018)

I suppose I was a bit unclear with my explanation. I was thinking of mounting the motor in-line with the drive shaft and coupling then together via a key way. So no chain or sprockets. 
Would it be a good idea to go to a smaller tire size if I'm worried about torque?


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## Jonkoehn (Jan 4, 2018)

Here it is with the motor in position(no c-face mount welded yet) the battery packs are just in to test the fit. Will build a mounting system later. It will have better rear tires on it as the project moves forward.


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## SWF (Nov 23, 2007)

Hi there!

I did an ATV conversion several years ago, and it was a great project and is handy to have around.

I believe the me1003 motor is a brushed motor, and it is better not to lug them down too much at very low rpms. You may be OK with a direct connection to your differential, but it would be better with some form of ratio reduction.

With my polaris conversion I left the 2-speed transmission in place and drove the input shaft of the transmission with the motor. The transmission drives both the front and rear differential. I can't recall for sure, but I think in low gear the transmission is about 11:1 and the differential ratio is probably similar to yours. At full motor rpm (~7500rpm) the ATV goes about 35mph, so I have plenty of power at low speeds.

I have been thinking about a version 2.0 ATV conversion, that could be sold to local farmers. I would probably go with a completely sealed drivetrain and independent motors on the front and rear wheels.

Happy to help if you have any questions.


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## Jonkoehn (Jan 4, 2018)

Wow a lot of really talented people on this form. I'm happy to be able to glean from everyone's experience.

What do you think about using a centrifugal clutch/torque converter? To avoid the pesky problem of stall torque. If I can get the motor spinning, I have 50 ftlb of torque (peek) for 30 second. But the stall torque is only 1.6 ftlbs.
I don't really have the option of a transmission at this point.


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## Jonkoehn (Jan 4, 2018)

BUT I guess I may have to redesign the who system. I certainly don't want to wreck the motor.


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## brian_ (Feb 7, 2017)

With 22" overall tire diameter (and ignoring that the effective rolling radius is a bit less than half of that), the axle turns once per 1.75 m (69") travelled. With a 3:1 reduction in the axle, the shaft turns once per 59 cm (23") travelled. That means that 10 mph (4.5 m/s) is only 459 rpm (unless I have made a math error).

For a motor with a design loaded speed of 2800+/-250 rpm, and a maximum speed of 3700 rpm, this is way too slow. I think it really needs another big reduction gearing stage, as SWF explained. This doesn't need to be a complex transmission: it could be a single-stage chain or toothed belt drive. Reduced tire diameter is not enough, because a tire short enough to produce a suitable motor speed would be far too small to use.

The Motenergy specs say 315 lb-in of torque, which is only 26 lb-ft... although that is probably supposed to be at the rated speed for maximum power (315 lb-in @ 2800 rpm is 14 hp or 10.4 kW). Even if it can produce 50 lb-ft at lower speed, multiplied by the 3:1 axle ratio that's 150 lb-ft, and divided by the tire diameter that's 164 pounds of thrust... not much to overcome drag and accelerate or climb with a whole loaded (driver, cargo) ATV, especially since it drops off with increasing speed.

A clutch might get over the initial starting issue, but won't help the fact that the motor is always turning way too slow to be effective. Gearing would help at all speeds and not involve slipping clutches (and their adjustment, energy loss, and wear).


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## Jonkoehn (Jan 4, 2018)

Great information! I'm in total agreement.

Now the issue is what's the best way to proceed. 

The original motor and transmission are a combined system. I may be able to access the transmission but I'm unsure. A chain isn't a good idea for our use because of the cattle manure.
my boss wants to avoid as much maintenance as possible. 

Dose anyone know of a good two speed transmission I could drop in? I suggested a inline gearbox to increase the torque. But he(my boss) doesn't want to lose any more speed.


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## Jonkoehn (Jan 4, 2018)

How about something like this?. Since I'm only running at 1/4 the rated motor RPM, if I install a 4:1 gear reduction my top speed won't change and my motor will be happy.

http://www.electricmotorsport.com/e...ducers/cast-iron-gear-reducer-4-1-c-face.html

Or do I need more reduction then that?
Sorry for all the ignorant questions.


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## brian_ (Feb 7, 2017)

Jonkoehn said:


> The original motor and transmission are a combined system. I may be able to access the transmission but I'm unsure.


It would likely be difficult, and that transmission wouldn't be ideal anyway.



Jonkoehn said:


> A chain isn't a good idea for our use because of the cattle manure.
> my boss wants to avoid as much maintenance as possible.


In this application, I assume that you would want any chain or belt to be enclosed.



Jonkoehn said:


> Dose anyone know of a good two speed transmission I could drop in? I suggested a inline gearbox to increase the torque. But he(my boss) doesn't want to lose any more speed.


But you wouldn't lose speed, as you have since realized...



Jonkoehn said:


> Since I'm only running at 1/4 the rated motor RPM, if I install a 4:1 gear reduction my top speed won't change and my motor will be happy.


That's what I'm thinking.



Jonkoehn said:


> http://www.electricmotorsport.com/e...ducers/cast-iron-gear-reducer-4-1-c-face.html


It's heavy - due to all the steel and cast iron - but makes sense to me.


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## Jonkoehn (Jan 4, 2018)

So with a 8:1 reduction (the differential is 3:1 and a additional 5:1 gearbox) i should be producing 232 ft lbs of torque at the wheels. not including rolling resistance and mechanical loss.

My non expert mind tells me, that should be enough. 

Any concerns from the experts? If not I'll take the leap and buy the gearbox.


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## SWF (Nov 23, 2007)

Jonkoehn said:


> So with a 8:1 reduction (the differential is 3:1 and a additional 5:1 gearbox) i should be producing 232 ft lbs of torque at the wheels.


To get your overall ratio you multiply the ratios of any transmission ratios between your motor and axle, so in your case would be 15:1. Likewise, torque at the axle would be 15 times the motor torque.

That C-face mounted gear reduction unit looks fine, but you may be able to find a small used multi-ratio transmission for less money, and it would also give you the option of different ratios for different jobs.


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## Jonkoehn (Jan 4, 2018)

I actually thought about using the bottom end of a 250cc dirt bike engine (just the transmission) they have low weight and and multiple gears.

Thanks for all the help. You guys are awesome!


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## Jonkoehn (Jan 4, 2018)

*Help with BMS.*

I'm in need of a BMS for my lithium battery pack. I have 10 nissan leaf cells in a, 10s 2p configuration. 36v 120amp.
Any suggestions?

Thanks!


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