electric tractor

I have this page bookmarked and have visited the page about 50 times ....

http://www.renewables.com/Permaculture/ETractorSpecs.htm

Here's how to build an electric tractor http://www.flyingbeet.com/electricg/

Update!

Wow... that is some neat stuff. I can see agri-tractors as definitely being operated viably on electric power. Highway semi-truck tractors on the other hand, not so much, but that is a different story all together.

My connection speed is way too slow to watch videos.

If you do a Youtube search for John Howe Solar Golf Cart there are a couple of excellent clips.

John Howe is a professor somewhere in Maine.  Took an electric golf cart, put PV panels on the roof, added a charge controller and an inverter, probably some other modifications.  A video shows him driving the golf cart into the woods, plugging in an extension cord, cutting a tree down with an electric chainsaw powered from the golf cart.

Pretty nifty rig.

If you do a Youtube search for John Howe Solar Golf Cart

Youtube says there are no matches.  Can you do the search and pass on the video link?

John Howe on Youtube with the solar golf cart, solar chain saw, solar tractor and solar MG.  I can't load the clip but this looks right.

That link is excellent.  One of the coolest things I've seen in a long time!  Thanks!

It was under "John Howe's electric chainsaw"
There is a part of the clip where he says he put about $7k into it.  Not too bad a price for mechanized fuel-less transport.  I suppose one could attach things to the golf cart for added versatility. 

Its essentially a solar PV generator on wheels.  Electricity where you need it.  Did you catch the part about plugging it into his house if the power goes down?

If it can be plugged in, it can be powered by this rig.  Chainsaws, lawn mowers, brush trimmers, power tools, post hole diggers, pumps, all sorts of uses.

There are communities where golf carts are allowed on local traffic roadways.  I've used these things in some of the plants I work at to get around.  25 MPH is easy to do.  We have to put limit switches on them to stay under the sped limit of some of these places or the guys will tear up the road!  I've loaded them up with a couple of hundred pounds of tools and materials, electric and gas models. 

What if you added a trailer hitch?  Hauling cargo to a farmers market would be a fine use.

Theres another video somewhere with an electric tractor, same idea as the golf cart.  Probably not too many horses, so you wont be baling hay, but smaller implements would work for sure.  brush hogs, finish mowers, tillers, a boom.  Lots of versatility. 

I'm all for simplicity and sustainable methods, but there is nothing wrong with some darn handy machines.

Here is the one I had.  When I bought it, it was labeled "monster golf cart" cuz of the lift kit and the knobby tires.  All electric.



Silent.

The big thing with electric tractors is that they have a lot of weight - so they improve traction.  Standard tractors usually fill the big tires with a liquid that gives the tractor more weight.

Also, with electric, you don't ever get too far from your charger.

I was concerned about the use of tracks - but the idea is that you get more traction and your weight is spread out - so less compaction.

A guy at work just picked up 11 acres, wants me to go look at it.  He wants to get some cows on 4 acres, raise tomatoes on 7.  We got to talking about tractors and fuel prices.  There are numerous projections that fuel prices will rise again.  The trend in food production is moving towards relocalization and at least all natural if not organic methods.  A solar powered electric tractor would be well positioned to take advantage of this developing trend.  Such a device need not be enormous.  Something able to plow and till a backyard garden would be in great demand.  The size would also be able to service a field of several acres. 

I'll be keeping this one in the back of my mind.

my grandparents bought a used Club Car golf cart years ago to drive around their small farm.  at some point, the roof broke and a tire went flat and batteries wore out.  it sat in the barn for at least five years, maybe closer to ten, just taking up space.  the keys were lost at some point.

well, I've been very slowly cleaning out the barn and that thing was taking up way to much space for something that didn't work.  so I took it to the dump.  psych your mind!  a few bucks for new keys and switch, $240 for six deep cycle six-volt batteries, a sore back from moving the batteries around, and it's right as rain again.  the roof is still busted up, but that should be easy to replace.

there's also a little trailer here that somebody bought to pull behind a riding lawnmower.  jury-rigged a hitch using a galvanized eye bolt and I've been hauling firewood around today.  I wasn't sure how the cart was going to handle towing, but it did fine.  I probably loaded up 300 pounds and I didn't notice any difference from when it was empty.  I suppose there are some fat golfers out there, so this shouldn't surprise me, but I was very pleased.  certainly not things I would have bought, but since they were already here I'm happy to use them.

I'm no electrical engineer, so forgive me if this is a dumb question, but could the charger (plugs into 120-volt AC) be modified to flow the other direction as an inverter?  using an electric chainsaw today would have saved me a pair of pants (don't ask).

Standard tractors usually fill the big tires with a liquid that gives the tractor more weight.

water and calcium chloride in my experience.  makes blowouts more interesting...

the one problem that's bothering me about these battery powered contraptions is the lead involved.  maybe it's negligible, but I can't help but think there's going to be some lead sulfate falling onto the ground at some point.  I guess proper maintenance and good design could prevent this altogether.

We use an electric tractor made by G.E. back in the early '70s. We bought it for $100 but it had been abused with overfilled batteries, corrosion from that, and miswired relays. It's a 36-volt model running on GC-2 golf cart batteries and it charges from our home's PV panels. We added a bit more weight (70 lbs.) by bolting on a 36-volt inverter to run an electric chain saw. Mostly we use it for cutting the 1 cord of boxelder firewood that we use in a year and to mow some trails and orchard. It has a 42-inch mower, a grading blade, a 1-bottom plow, tire chains, and a 30-inch rotary tiller. The tiller is nice for cutting up a green manure crop after mowing it, but I'd never think about tilling on bare ground since a shovel or fork works so much better without over-fluffing the soil. You can see the tractor by clicking on our web page at http://www.geopathfinder.com/9659 , or there are more details found on links at that page.

Bob Dahse

tel jetson wrote:

I'm no electrical engineer, so forgive me if this is a dumb question, but could the charger (plugs into 120-volt AC) be modified to flow the other direction as an inverter?  using an electric chainsaw today would have saved me a pair of pants (don't ask).

Sorry, but the answer is no.  The charger takes the AC and converts it to DC, a fairly simple task.  Converting DC to AC, not so simple.  Think of it this way: it's a simple matter to take your log and split it into pieces; it's quite a different matter to take those pieces and put them together into a solid log.

Nice analogy!

Inverters, though, are often built with on-board chargers. The Tripp-Lite APS 3636VR on our Elec-Trak E-15 tractor can charge the tractor's batteries at 20 amps OR it can run two AC circuits at 15 amps each. That translates to two electric chainsaws running at the same time, full power. Not that I'd need it but it's nice to have some reserve capacity to ensure durability. The biggest downside is modified sine-wave output instead of true sine-wave. The cheaper option was over $700. As bad as that was, the sine wave option is REALLY pricey!

Bob.

Walk wrote:
Nice analogy!
[font=Verdana]Thanks![/font]
Inverters, though, are often built with on-board chargers. The Tripp-Lite APS 3636VR on our Elec-Trak E-15 tractor can charge the tractor's batteries at 20 amps OR it can run two AC circuits at 15 amps each. That translates to two electric chainsaws running at the same time, full power. Not that I'd need it but it's nice to have some reserve capacity to ensure durability. The biggest downside is modified sine-wave output instead of true sine-wave. The cheaper option was over $700. As bad as that was, the sine wave option is REALLY pricey!

Bob.

One thing to point out: The cheapest and simplest DC-to-AC inverters used mechanical devices to "chop up" the DC to make AC.  The result is what's called a square-wave.  These kinds of inverters need to have a LOT of electrical shielding, otherwise the interference it produces will wipe out all radio communications in the area.  The resulting square-wave AC, for all intents and purposes, can only be used in tube-based electronics or incandescent bulbs.  Unless the motor is specifically designed to work with square-wave AC, square-wave AC will "seriously reduce the life" (i.e., burn out) your standard AC motor.  Modified (aka, "stepped") sine-wave AC can generally be used by both AC motors and most electronics.  Generating pure sine-wave AC from DC with any kind of efficiency is a non-trivial task, and is only a concern if you're using very expensive electronic equipment.

One type of inverter that used to be available for the Elec-Trak was simply two motors joined at the output shaft. One was 36-volt DC and the other was 120-volt AC. While it was heavy (for an equivalent output), and only peaked at about 80% efficiency, it was fairly inexpensive and not much less efficient than a modern, $2000- $3000, sine-wave, electronic inverter (which runs about 85%). Efficiencies on the cheaper modified-sine-wave inverters is usually listed as 95+%, but this figure includes all of the high-frequency transistor switching noise that motors and transformers simply convert into heat and vibration ("hum").

I looked in vain for the 36-volt chainsaw that used to be available for the Elec-Trak but didn't find one. Besides the high cost of what's now a hard-to-find antique, I would have had to lug around a heavy cable to handle the low-voltage current. 120-volt is easier to use but inverters are their own trade-off, cost-wise and in efficiency loss.

Bob.

Electric tractors are cool!  I want one with a PTO and a front end loader!

I don't see the need to put photovoltaics on each device (unless you are trying to sell solar panels).  Seriously why not just go with battery powered machines?  Then plug in the batteries at a central power supply when not in use.  In some cases photovoltaics may be the best power supply, in other cases not. 

One human on a bicycle can sustain 300W of power output all day long.  A horse easily sustains 740 W (1 hp), and can generate 10 hp at a peak pull.  If you can turn a wheel you can turn a generator.  People anywhere around the world can build this technology and it doesn't cost thousands of dollars.

Many people are deterred from going off the grid because they worry about having a perfect sine wave and the highest possible efficiency.  Cheap inverters are available at truck stops.  The wave form approximates a sine wave (definitely not a square wave) they work great for everything I've tested them on, including some pricey electronics.  TVs and stereos run on these cheap inverters and function perfectly with no distorted signal.   I can also tell you that the waveform coming out of a gasoline powered generator is noisy and irregular as all get out, yet construction workers run their power tools off that all day long without ruining the tools.  I have also observed that many devices work fine if the voltage is 20% above or below normal.  My point is don't let the perfect be the enemy of the good.  We can make these systems work far more cheaply and with more slop than anybody will ever recommend. 

While I agree with your conclusion the premises are a bit flawed. Yes, a human can maintain 300 watts for a while but, unless you are an Olympic athlete, not all day. I tried a pedal generator 20 years ago, and I used to be a racing cyclist, but 300 watts is a lot of output!

Regarding generators and inverters, the generators vary a lot depending on if they use straight motor output or run through an inverter. Motor output is a lot smoother than a cheap inverter. And the other name for a cheap inverter's output is "modified square wave". Modified sine wave sounds nicer, and more marketable, but the sad fact is that, depending on the amount of load and the rating of the inverter, sometimes it is indeed more like a square wave. This causes the steel plates in a transformer to move microscopically against each other, generating hum and heat. And motors heat up due to the harmonics and switching frequencies generated by the sudden rise and fall of the waveform.

Either way, yes, cheap inverters work but not for long (ask my next-door neighbor), and they wear out equipment pretty quickly. If you don't mind throwing away electronics periodically that's fine. But if you buy quality tools and electronics and expect them to last it's far better to use an old motor-generator inverter or a switching frequency filtered sine wave model. The best option is straight DC from a renewable source, whichever is most available in your location. Many AC electronic devices transform AC to low-voltage DC and you can tap into those secondary voltages or use cheap DC-DC converters to match what they require.

I love our DC-powered tractor, bikes, and car but I'd never consider equipment-mounted PV to be more than a trickle-charging source. Too much surface area is needed, at least with present technologies. We use our house PVs to charge all the portable stuff and that works great. If we had wind or water power we'd do the same.

Walk wrote:
We use an electric tractor made by G.E. back in the early '70s. We bought it for $100 but it had been abused with overfilled batteries, corrosion from that, and miswired relays. It's a 36-volt model running on GC-2 golf cart batteries and it charges from our home's PV panels. We added a bit more weight (70 lbs.) by bolting on a 36-volt inverter to run an electric chain saw. Mostly we use it for cutting the 1 cord of boxelder firewood that we use in a year and to mow some trails and orchard. It has a 42-inch mower, a grading blade, a 1-bottom plow, tire chains, and a 30-inch rotary tiller. The tiller is nice for cutting up a green manure crop after mowing it, but I'd never think about tilling on bare ground since a shovel or fork works so much better without over-fluffing the soil. You can see the tractor by clicking on our web page at http://www.geopathfinder.com/9659 , or there are more details found on links at that page.

Bob Dahse

Very cool!

Does it get decent traction?  Especially when plowing?  How are the batteries in the cold?

Mangudai wrote:
One human on a bicycle can sustain 300W of power output all day long.

??

I remember in high school a guy had rigged a 60 watt light bulb up to an exercise bike.  I remember that to get the light to glow even a slightly reasonable amount, you had to REALLY pump on that thing! 

Is there a video showing a bike and a bunch of bright light bulbs perhaps?

paul wheaton wrote:
??

I remember in high school a guy had rigged a 60 watt light bulb up to an exercise bike.  I remember that to get the light to glow even a slightly reasonable amount, you had to REALLY pump on that thing! 

Is there a video showing a bike and a bunch of bright light bulbs perhaps?

peak anaerobic output for reasonably active folks is generally well above 300 Watts.  10th percentile for men is around 570 Watts, and 90th percentile is over 800 Watts.  my guess is that there was substantial loss in the high school experience you mention.  could it have been under-geared?  was riding it like trying to pedal in a low gear downhill or like a high gear uphill?

those numbers are for anaerobic exertion, though, and it would be unusual for a person to sustain that peak output for more than a few seconds.

Yes, Paul, plenty of traction with 6 heavy batteries on-board along with a 70 lb. inverter mounted low and centered. We are still using the original 1971 tires! We don't run it in the winter as batteries don't do so well then. No PTO, but it uses multiple 36-volt outlets front and rear for DC motor powered options. Those actually included snow-blowers, front end loaders, mowers, rotary tillers, chainsaws, etc. They aren't terribly hard to find and some of the folks I know who have one (or more) have switched from the original stepped speed control to an AllTrax PWM speed controller.

Regarding peak power output of humans, if you've ever tried putting out sustained wattage on a power cycle you'll quickly realize why humans started domesticating oxen and horses!

This says 100 watts.  Another video claims 250 watts.  So a healthy person could do 300.  "All day long" may be a stretch. 

Mangudai wrote:

One human on a bicycle can sustain 300W of power output all day long. 

so over 12 hours the power output would be 3600w/h which converts to 3095Cal thats output now assuming that we convert food to output at about 33% efficiency which I am sure is overgenerous the man doing this would need a 10,000 calorie a day diet
just playing with the math

brice Moss wrote:
so over 12 hours the power output would be 3600w/h which converts to 3095Cal thats output now assuming that we convert food to output at about 33% efficiency which I am sure is overgenerous the man doing this would need a 10,000 calorie a day diet
just playing with the math

I lived with a professional bicyclist for a couple of years.  apart from his two-week break at the end of the racing season, he regularly ate well over 10,000 Calories daily, and he was thin as a rail.  he spent a lot of time and money preparing all that food.  over the winter, quite a bit of his training was on a set of rollers.  while I don't think he would object to those rollers driving a generator, one of the advantage of training on rollers is related to their lack of resistance.

Walk wrote:this figure includes all of the high-frequency transistor switching noise that motors and transformers simply convert into heat and vibration ("hum").

Good news!

While you can't (cheaply) build an inductor with zero electrial resistivity, the impedance of an inductive load is not dissipative: it stores energy as a magnetic field, rather than releasing it as heat.

You're right that the hum is from magnetostriction of the core material, which dissipates energy, but that's mostly un-related. Smoothing out of high-frequency aspects of the AC by motors and transformers is, in large part, accomplished by very briefly storing energy as a magnetic field, and bleeding it back into the circuit as electric current a very short time later.

I think the quoted efficiency figures are pretty much correct.

would using hydraulics for a front end loader suck a lot of juice since the pump would run all the time?

could use linear acutuators but the are slow and expensive for sizes you would need .

any ideas or thoughts?

I would love to build an elec tractor

Not to rain on your parade  , but the electric tractor .. like a lot of myths on the Internet is a non starter if one thinks it is going to replace any existing fossil fuel tractor.

I have 3 EV's and in my opinion the watts are just not there to rip, plow , disc, cultivate or any other job that a  regular tractor does.

Well, that's a tough post to follow. However:
I might be a little late finding this thread (and awesome forum), but in case anyone's interested I'm working on converting standard Farmall Cub cultivation tractors to 48v electric. I have one currently up and running, my 'working prototype,' and it seems to have enough energy in the battery pack to operate from 2-4 hours on a charge (depending on load). Website at http://www.reinventionsllc.com .

jmy wrote:
Not to rain on your parade  , but the electric tractor .. like a lot of myths on the Internet is a non starter if one thinks it is going to replace any existing fossil fuel tractor.

I have 3 EV's and in my opinion the watts are just not there to rip, plow , disc, cultivate or any other job that a  regular tractor does.

So, the guy that is getting excellent results for a fraction of the cost, is actually ... not?

I remember reading stuff that an electric car could never go faster than a gas powered car and now we have the tesla - which goes faster than any porche, ferarri, corvette and most lamborginis. 

I think it is probably easy to create an electric tractor that sucks.  And, my impression so far, is that it is almost as easy to create an electric tractor that kicks butt on gas or diesel tractors.

If that is not the case, I would really like to understand why/how.

Well, I'm a pretty strong proponent of electric vehicles and equipment. This is for many reasons, but one large one is that electricity is very flexible in a way that fossil fuels are, typically, not. This flexibility comes from the way electricity can be generated in many, many different ways- some don't even involve much pollution- and then stored and used with virtually no waste (little noise, no exhaust gases, little heat) wherever you want it.

Check this out. In September and October 1947, the standard bone-stock Farmall Cub was given a thorough shakedown in  Nebraska Tractor Test No. 386. In the test, the highest fuel efficiency obtained was "10.94 horsepower hours per gallon of gasoline," operating the tractor at maximum load. With one horsepower equal to 746 watts, this converts to 8.16 kwh output per gallon of fuel consumed. That's a decent amount of energy, right?

Now: Chemically, a gallon of gasoline contains 33.4kwh of energy! What happened? Somewhere along the line, between tank and tires, we lost 25.42 kwh, almost 76 percent loss! I'm pointing at the ol' internal combuster, myself.

A noteable EV disadvantage comes from the way we can store electricity. Right now, it's pretty much restricted to chemical batteries. And they just aren't quite as energy dense as, say, gasoline. For a point of reference, the four large deep cycle, lead-acid AGM batteries I'm using to power my electric Farmall contain only 4.8kwh when fully charged. The batteries are the key puzzle of virtually any contemporary electric vehicle venture. However! This difficulty of storing a vast amount of energy as electricity is offset, at least partially, by the high efficiency inherent in electric drive systems. Even some of the worst electric drivetrains can still claim about 80% efficiency, or only 20% loss. And the best? Many are pushing 95% efficiency.

paul wheaton wrote:
I think it is probably easy to create an electric tractor that sucks.  And, my impression so far, is that it is almost as easy to create an electric tractor that kicks butt on gas or diesel tractors.

If that is not the case, I would really like to understand why/how.

Now for the hard part. You'll notice that, as above, a brand new gasoline powered farmall can apparently do over 8 kwh of work on a gallon of fuel, after inefficiencies. My electric conversion? Even if 100% efficient (it's not), can do about 60% of that work per charge. It would be a simple matter to double the size of the battery pack; much beyond that, though, space, expense, and excessive weight become concerns.

So, a good rule of thumb to gauge if you could use an electric tractor or not: if your gasoline or diesel equipment is running perfectly (this is important to use the comparison) and you use more than a gallon of fuel at a stretch (no breaks or idle time), then your work would likely be interrupted by recharging. If you dont use a gallon at a time, even if you take brief breaks, then you could potentially be charging your electric tractor. With inexpensive components and a 120v outlet, plan 2 hours of charging for every hour of moderate intensity use.

As far as instantaneous energy output goes, or how much 'power' the operator feels, the electric cub can at least equal its gasoline counterpoint- and so can any adequately sized electric drive system. Runtime, then, is virtually the only limiting factor between farmers and electric equipment, and with a well designed plan of implementation, might not be an issue at all.

Ken Peavey wrote:
My connection speed is way too slow to watch videos.

Click on play and then as soon as the video starts to play, click pause. The video will carry on loading (slowly) but not playing. Open another browser and carry on surfing the internet. Check back periodically to see if the video has loaded. When it has, you will be able to watch the video without any problems.

There was an article on an electric tractor in Farm Show, vol 34, no 4, 2010, "Texas Ag Students Create a Battery Powered 8N." They replaced the tractor's engine with a 60 hp electric motor salvaged from a large forklift.

here is another great write up of an electric tractor. one issue with converting these old tractors is the RPM. Electric motors for EV use like to spin about 6-7k rpm. these old tractors had an RPM around 2k. when you run the electric motor slow it pulls a lot of amps and produces a lot of heat.

http://forums.somethingawful.com/showthread.php?threadid=3115766&userid=0&perpage=40&pagenumber=1

Back in the late 80's I was working as a "wrench" for an outdoor equipment service center.  They called me the service manager but nobody else turned any wrenches so that made me the management and labor too. LOL  We had an old worn out electric fork lift that I wanted to keep when the owners couldn't get along well enough to keep the business.  I tried to get that forklift but was outbid when they had the bankruptcy auction.  I was planning to build an electric tractor.  The forklift needed all of the hydraulic ram seals replaced and a new battery pack but other than that it was fine.  I am currently building a motorcycle sized "trike" that hopefully will become a serviceable vehicle for local trips.

Here is the older model of the Heckeroth

Yeah I saw this one while "surfing" youtube.  Very cool.  I acquired a 96 volt DC  brushless permanent magnet motor several years for free so like all of the "valuable junk" I have been collect over the years I saved it for future use.   I like the design of this tractor because it is much like an old VW Bug.  The weight is over the drive wheels.  Because of the demand it is nearly impossible to get high amp hour 96 volt Lithium Iron Phosphate batteries though.  I would love nothing better than using a photovoltaic array as a roof so I could just go out and run the tractor driving "in the shade." LOL