# Electric ATV



## Zoar (Sep 16, 2013)

I need to convert/build an Electric ATV. 

I live on 21 acres of rather steep terrain. My home is located at the top of this property. There are nine amazing waterfalls on the property, It drops about 300 feet over a third of a mile. It is mostly (99%) forest. 

I have been making all my electricity (via solar) for the 8 years since I bought the land and built on it. I heat with solar and wood.

I need to harvest the wood from the land but I have no ATV vehicle.

So, I need an Electric ATV. I will charge it from my solar electric. Right now I go from 24 VDC to 110Volt AC. But can buy another inverter if need be. 

The ATV's primary purpose is to haul wood or haul tools/chain saw/deer. The terrain is steep but not too steep for an ATV. I do not need speed. max speed of 10 to 12 miles an hour is fine. I need torque. Enough to haul me and a load of wood (like an 1/5 - 1/4 of a face cord) up some fairly steep trails.

I am looking for a donor ATV and any incites and experience from people here.

I do have a shop at work (not at my home) where I can do the build as long as it doesn't take me more than a month or so.

Slow N Steady: High torque and low to the ground with hauling some weight up hill capability.


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## RIPPERTON (Jan 26, 2010)

Hi Zoar
we converted this Atomik 4x4 with a 5kW QS hub motor.
It did 74kmh with the 350cc petrol engine and already does 62kmh with a single electric motor. There is another 5kW hub motor going into the front of the quad for true 50/50 4x4.
The original 4x4 had the front wheels only driving at 80%.
The little cardboard box between riders feet is a 24s3p A123 pouch battery which should do 50km

http://www.youtube.com/watch?v=8spmzr-tCTs&feature=c4-overview&list=UUoOd7A2JVRmeuaEfGbO7f_g


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## Zoar (Sep 16, 2013)

RIPPERTON said:


> Hi Zoar
> we converted this Atomik 4x4 with a 5kW QS hub motor.
> It did 74kmh with the 350cc petrol engine and already does 62kmh with a single electric motor. There is another 5kW hub motor going into the front of the quad for true 50/50 4x4.
> The original 4x4 had the front wheels only driving at 80%.
> ...


That is a very sweeet electric machine you made there!

I need mine to be much more about torque and power. It will be a work machine. Slow and steady. Wonder if anyone has an electric motor, battery, controlled, system recommendation?


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## PStechPaul (May 1, 2012)

Here are some calculations from my http://enginuitysystems.com/EVCalculator.htm. The slope you have is about 300 feet in 1800 feet or about 17%. I used 700 kg or about 1500 pounds for the quad and payload. At 10 km/h (6 MPH) it will require about 3.7 kw or 5 HP. This is 370 W-h/km or 594 W-h/mile, but you should require very little power going downhill and probably can use regeneration during that trip. So for a 2/3 mile round trip you will use about 400 W-h. 

I'm not very familiar with quads and ATVs, but more so with tractors, which may be a better choice. You can get them with front-end loaders (FELs) that might come in handy for loading wood and lifting logs for easier cutting. I think this would be an application where deep-cycle lead-acid batteries would be ideal, as extra weight may be useful to get good traction. You can get 100 Ah batteries at Walmart for about $60 and 45 pounds each, and four of them will give you 4.8 kWh or enough for about ten round trips.

I'll make a pitch for using a three phase motor and controller, but with a 48V pack a small forklift motor and PWM controller might be good. With proper gearing and a little less speed you could use a 2-3 HP treadmill motor and controller, although you may need more voltage. Eight 12V batteries will give 96 volts which should be enough. 

But if you go with a standard three phase motor you can use automotive inverters to get the 270V DC bus required. I plan to get some 1500 watt units for $50 each which use 24 volts input. Four of those would do nicely. I am making a small tractor now that will use this method, but it might be a while before it's running. But I think it would be a viable option, with a total cost of:

2-3 HP motor: $100
3-5 HP VFD controller: $250
4 12V 100Ah batteries: $250
4 1500W inverters: $200
Total: $800

I have a similar situation, although I have only 2.5 acres, and most of the firewood is located on a hill about 80 feet above the house and accessed by about 800 feet of rough dirt road. Since I'll be going up light, and back down heavy, I might even be able to regain more energy than I use!


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## Zoar (Sep 16, 2013)

Interesting. Helpful. Thank you! 

Some places are steeper than 17% and those are on the trails. Those are the few but critical places I am concerned about, not the average. Most tractors would flip trying to go up these places. That is why I am thinking a slow steady workhorse ATV. My neighbor has a two wheel drive high speed ATV and it cannot get up these places due to not enough traction /torque to the wheels. He just spins. I am therefore thinking at least a 5HP or even 7.5HP motor based on your calculations. (Some friends who went down one of these trails in a truck they had to winch the truck back up over one of these steep spots. I have three main trails that lead down to where the wood is {and where the deer are] and each one has one of these steep places, sometimes no more than 15-20 feet in length but the thing is if you can't get up that spot, you are STUCK down there because trying to go through the actual wooded areas around that trail are even STEEPER! and full of trees!) So, again, I am thinking 4 wheel drive, low to the ground, ATV, built for torque and NOT speed.

I am interested in learning more about the DC to AC conversion and these Inverters you mentioned. Do you have a link to this type auto inverter. I am just not familiar with them. (I am a DC inverter to AC house current guy)


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## PStechPaul (May 1, 2012)

The inverters I am speaking of are DC to AC, but I have opened up the one I have and brought out the 270 VDC that is used to make the 220 VAC modified sine wave. I could make my own, but if I can get 1500 watts for $50 it's a good deal. Actually the one I have is labeled 1000 watts but in reality it is 400 watts with 800 watts for short time and 1000 watts peak. So the 1500 watt units may really be only 600 watts, but four of them should provide a solid 2400 - 3000 watts or 4 HP continuous. 
http://www.ebay.com/itm/151073597579

As for the power you need, unless you want to race up those steep hills, you don't need any more that 3 or 4 HP. You will probably be geared down to a crawl for those sections, and for 2 MPH (still pretty fast) on a 25% slope with 1500 pounds, you only need 2.25 HP. What you really need is torque to the wheels, and thrust delivered to the ground. This example needs 424 pounds of thrust which is also 424 lb-ft torque if you have 24" diameter tires.

For such a steep slope, you will probably need every bit of a four wheel drive with limited slip or locking differentials, or true all wheel drive. And it may be dangerous if you lose traction on one side and go sideways such that you could get wedged between trees or possibly roll over. I think you may need a winch to negotiate these hills. A track vehicle is another option, but they are hard to come by and are expensive and require a lot of maintenance. 
http://www.ebay.com/itm/Personal-Tracked-Vehicle-Magic-Carpet-TWIN-PACK-plans-/190777987082

http://www.ebay.com/itm/Struck-Magnatrac-MD567-Mini-Dozer-Tractor-Crawler-Loader-15hp-/171126531767


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## Tesseract (Sep 27, 2008)

PStechPaul said:


> ...But if you go with a standard three phase motor you can use automotive inverters to get the 270V DC bus required.
> ...
> I plan to get some 1500 watt units for $50 each which use 24 volts input. Four of those would do nicely. I am making a small tractor now that will use this method, but it might be a while before it's running.


You really think this is appropriate advice to give to someone with an unknown level of electronics skill/knowledge? Especially since you haven't even tried it yourself, apparently?!?!


To the OP - a small AC system is a reasonable solution for you, but even if you are very knowledgeable about electronics you should still stick to off-the-shelf controllers and motors (unless you have a burning desire to reinvent the wheel). 

Your estimated power requirements are entirely within the realm of the typical forklift and golf cart, so any motor/controller system (AC or DC) designed for such applications will work for you and because of the higher manufacturing volumes (compared to DIY EVs) they will be fairly inexpensive, too. That said, be careful with some of those golf cart motors, as they often have a female splined output shaft and don't come with a drive-end bearing (they are intended to bolt onto the differential directly).


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## elevatorguy (Jul 26, 2007)

I would keep it simple, I built a Equad a few years back http://www.evalbum.com/preview.php?vid=4677
I think a gearing change on similar setup would work for your application.
I have a 4 HP motor but run 48 volts, it has been a workhorse for me but I would gear lower if I had it to do again, motor heating can be an issue at low rpm.


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## Zoar (Sep 16, 2013)

Tesseract said:


> You really think this is appropriate advice to give to someone with an unknown level of electronics skill/knowledge? Especially since you haven't even tried it yourself, apparently?!?!
> 
> 
> To the OP - a small AC system is a reasonable solution for you, but even if you are very knowledgeable about electronics you should still stick to off-the-shelf controllers and motors (unless you have a burning desire to reinvent the wheel).
> ...




Thank you. That is also very helpful and sage advice. I certainly have some experience putting electrical systems together but it is generally as an overall supervisor and not as a hands-on tinkerer. And yes on this project, I am thinking more like components, as much as possible.

I received this recommendation:

http://www.gngebike.com/48v800w-cart-kit

What do you guys think?

Also to reiterate. Slow and steady. And there are places that are more than 25% grade. More like 40%. Not many but when going up a trail and that spot has to be negotiated that is the spot you need to go up. I have done it in a bulldozer but I do not want a bulldozer I need a small ATV to carry me and some wood and maybe a deer. Again I am in NO hurry. I am not racing around my woods, going for thrills, this is strictly a work vehicle. Electric. And I would love to charge it with my solar panels (24 volt DC system to 110VAC through inverter).

And what do you guys think of this donor(with a wooden BOX for the wood)?
http://binghamton.craigslist.org/sno/4057109070.html

My first thought was it is not the best design for hauling some wood or dragging a deer but I'm just putting it out there for others' input.

Also I have friend who has machine shop and he's welder with years of fabrication experience so we can fabricate drive parts to go from existing drive components to gear box.


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## PStechPaul (May 1, 2012)

Sorry if the technical advice might not be appropriate for a novice. I have only proven that it can spin the 2HP motor but I have not tried to get much power out of it. 

The 48V 880W package might do the job, but it seems to be mostly designed for bikes, and the power output for the various gears seems very odd. The power should be the same for all gears, and perhaps even less for higher ratio (low gear) because of mechanical losses. It is the torque that is much higher. Also check the full price which involves shipping of $268 or more.

The 40% grade sounds very dangerous to me. I searched for "maximum grade ATV" and found these:
http://www.polarisatvforums.com/forums/atv-general-discussion/15461-maximum-grade-question.html (a situation similar to yours)

http://en.wikipedia.org/wiki/All-terrain_vehicle
http://www.can-amforum.com/forums/can-am-outlander/29427-when-steep-too-steep-6.html
http://forums.atvconnection.com/kawasaki/237203-how-steep-too-tippy-steep-2.html

From what I gathered, steep hill climbing uses speed and forward momentum to achieve it, and if you don't quite make it, you are pretty much doomed to flip over backwards. This is how it seems to be done:





 
It might be best to use a bulldozer to cut switchbacks for a safer grade. Otherwise maybe load the wood (or deer) onto a cart at the bottom and use a winch on the ATV to drag it up the hill. This is not an issue of power or torque, but traction, and that will vary considerably with weather and soil conditions. A rock or a root could cause bouncing and lost traction and a sideways slip that could be very bad.


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## Zoar (Sep 16, 2013)

PStechPaul said:


> Sorry if the technical advice might not be appropriate for a novice. I have only proven that it can spin the 2HP motor but I have not tried to get much power out of it.
> 
> The 48V 880W package might do the job, but it seems to be mostly designed for bikes, and the power output for the various gears seems very odd. The power should be the same for all gears, and perhaps even less for higher ratio (low gear) because of mechanical losses. It is the torque that is much higher. Also check the full price which involves shipping of $268 or more.
> 
> ...


Maybe I do not understand grade. When I calculate it I compare it to angles of a 0 degrees, 45 degrees and 90 degrees. Obviously 0 is flat. 90 would be straight up and 45 would be directly in the center of those two. My worst spots grade is LESS than that which is why I estimated 40 but it is still steep, steeper than 28 degrees. You will NOT flip at 45 degrees in most situations as long as you are not weighted to high up on the vehicle. And as I said above these couple of places are like 15 feet long, that is IT. the rest of the trails are LESS grade than that, I was just giving out the couple of spots of worse case.

Anyway. 

I appreciate the input thus far. That 48 volt 800 watt "system" looked good. I just wanted your sage experience. I did not want to buy from China and yes the shipping is significant. My last 24 volt DC wind mill I bought from China sucked. ...I will continue to research.


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## PStechPaul (May 1, 2012)

Percent grade is somewhat non-intuitive. It would seem logical that a 45 degree slope where you rise at half the maximum (vertical) would be 50% and the maximum grade would be 100%. But instead, it is the ratio of rise to run, and a vertical slope would be infinite grade. It is explained here:
http://en.wikipedia.org/wiki/Grade_(slope)

I have also updated my http://enginuitysystems.com/EVCalculator.htm so that it now shows the angle and percent slope for the acceleration. The default 0.98 m/s/s is 1/10th the gravity constant f(G) and corresponds to 5.7 degrees or 10.05% slope. So for most grades you can use the acceleration/f(G). For acceleration of 0.5G (4.9 m/s/s) the slope is 30 degrees and 57.7%.


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## Zoar (Sep 16, 2013)

PStechPaul said:


> Percent grade is somewhat non-intuitive. It would seem logical that a 45 degree slope where you rise at half the maximum (vertical) would be 50% and the maximum grade would be 100%. But instead, it is the ratio of rise to run, and a vertical slope would be infinite grade. It is explained here:
> http://en.wikipedia.org/wiki/Grade_(slope)
> 
> I have also updated my http://enginuitysystems.com/EVCalculator.htm so that it now shows the angle and percent slope for the acceleration. The default 0.98 m/s/s is 1/10th the gravity constant f(G) and corresponds to 5.7 degrees or 10.05% slope. So for most grades you can use the acceleration/f(G). For acceleration of 0.5G (4.9 m/s/s) the slope is 30 degrees and 57.7%.


Using the attached chart from the internet I ESTIMATE a about 50% grade / angle or about 30degree using the attached. But again. This is ONLY a couple of spots on my trails and each spot is ONLY 15 to 20 feet long. Most of the grade is much less.

http://en.wikipedia.org/wiki/Grade_(slope)

The chart I am using is in the "Nomenclature" section. The red and grey chart.


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