300 kW EV Tractor vs 400 hp Diesel

[Eeyore]

"Paul E. Schoen" wrote:

Losses are always part of the equation, but a reasonably well engineered
system might be rather efficient even using "low voltage" cable. For
something like 90 HP, or 66 kW, a three phase 480 VAC supply at 80 amps per
phase could use #2 portable cordage.

OK, but how long will that cable last being dragged around a field with sharp
stones, even if one of the tractor attachments doesn't sever it just for good
measure ? Arken Sparken time !

Sorry, but it sounds like one of the most utterly insane ideas ever from basic
principles.

Graham

 

[Don Bowey]

On 7/25/08 12:44 PM, in article 488a2d8e$0$19691$ecde5a14@news.coretel.net,
"Paul E. Schoen" <pstech@smart.net> wrote:

"Don Bowey" <dbowey@comcast.net> wrote in message
news:C4AF6CD8.BF560%dbowey@comcast.net...
On 7/25/08 10:18 AM, in article 488A0AD7.E569296@hotmail.com, "Eeyore"
rabbitsfriendsandrelations@hotmail.com> wrote:



Bret Cahill wrote:

Losses aren't an issue.

I just love the stuff you come up with !

Graham


I'd like to know what he thinks losses are.

(snip)
Should I assume you posting to tell me what HIS concept of losses is?

 

[John Fields]

On Thu, 24 Jul 2008 20:56:36 -0700 (PDT), Bret Cahill
<BretCahill@aol.com> wrote:

That's the point of the trolly wire. ?The size of the battery can be
reduced by 1 - 2 orders of magnitude because, unlike an EV or plug in,
the tractor charges up every 6 - 10 minutes, after each pass.

Bret, if the tractor goes (what was it?) 1 mph or so, and it needs 10 minutes for one pass (5 min each way), then the field is no
wider than 440 feet.

Is that a reasonable assumption ?

No. As one poster citing government and industry material pointed
out, tractors generally go much faster.

If so, why not just use a high-voltage extension cable ?

Another moveable wire off of the stationary wire?

Actually, a 10kV line can be miles long without too many losses (for the 300 kW that you need).

Losses aren't an issue.

---
Really?

Let's say you need 400HP out of a motor which is 90% efficient and
that the input voltage to the motor comes from a PWM controller which
is also 90% efficient and which is driven with a battery with a
charge-to-discharge efficiency of 90%.

That means the efficiency, from battery to motor shaft will be:


Et = E1E2E3 = 0.9 * 0.9 * 0.9 = 0.729 ~ 73%


One horsepower is equal to 746 watts, so our 400HP converts to:


746W * HP 746W * 400HP
P = ----------- = -------------- = 298 400W ~ 300 000 watts,
HP HP

which is 300 kilowatts.

Now, since the efficiency is running at 73% we'll need to put in:


Pout 300kW
Pin = ------ = ------- ~ 411 kilowatts,
E 0.73

which means we've wasted 111 kilowatts to get 300.

But wait... It gets worse.

Let's say the battery charger is 90% efficient and the transformer
feeding it from the HV transmission lines is also 90% efficient.

as before:


Et = E1E2 = 0.9 * 0.9 = 0.81 = 81%,


so to get 411 kilowatts out of the charger we have to put:


Pout 411kW
Pin = ------ = ------- ~ 507 kilowatts
E 0.81


into the transformer primary.

Using the 17kV lines someone earlier posted were standard, the current
in the primary and the HV lines will be:

P 5.07E5W
I = --- = --------- = 29.82A ~ 30A
E 1.7E4V

Now, just for grins, let's say that the battery charges for a minute
and that on that charge the tractor runs for six minutes (your
numbers, as I recall) and then recharges and discharges again, ad
infinitum. Under that kind of duty cycle the current on the HV side
will have to increase by a factor of six in order to fully charge the
battery in the tome allotted. That means that the primary current
must rise to:


Ip = 30A * 6 = 180 amperes.


Here's the best part...

Let's say that we have 10 miles of #0 AWG wire strung from the
substation to our transformer.

#0 AWG wire has a resistance of about 0.52 ohms per mile, so that 10
mile stretch will have a resistance of:


R * Dt 0.52R * 20mi
Rt = -------- = -------------- = 10.4 ohms,
D 1mi


will drop:


E = IR = 180A * 10.4R = 1872 volts,


and will dissipate:


P = IE = 18A * 1872V = 33 696W ~ 33.7kW.


Our total losses, then will be


P = Pin - Pout = (507kW + 33.7kW) - 300kW = 240.7kW ~ 241kW


So, for 300kW out we've had to put in 541kW, which is an efficiency
of:

Pout *100 3E5W * 100
E = ----------- = ----------- ~ 55.5%
Pin 5.41E5W


Which translates into that for every dollar you're paying for energy
you're throwing away about 45 cents.

Losses aren't an issue, huh?

JF

 

[John Fields]

On Fri, 25 Jul 2008 13:57:23 -0700, "Rob Dekker" <rob@verific.com>
wrote:

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message news:488A3319.C58B5C61@hotmail.com...


"Paul E. Schoen" wrote:

Losses are always part of the equation, but a reasonably well engineered
system might be rather efficient even using "low voltage" cable. For
something like 90 HP, or 66 kW, a three phase 480 VAC supply at 80 amps per
phase could use #2 portable cordage.

OK, but how long will that cable last being dragged around a field with sharp
stones, even if one of the tractor attachments doesn't sever it just for good
measure ? Arken Sparken time !

Yes. That would be crazy.


Sorry, but it sounds like one of the most utterly insane ideas ever from basic
principles.

Basic principles ?

---
Sticks and stones may break my ohms...

JF

 

[disgoftunwells]

On 23 Jul, 23:03, BretCah...@peoplepc.com wrote:

The Tesla is powered by 7,000 Li-Ion laptop batteries for an output of
200 kW.

A similarly powered 300 kW electric tractor (10,500 batteries) would
turn a 400 hp articulated 22 gallon/hour diesel tractor every which
way but loose in a tractor pull which apparently is vitally necessary
education as well as entertainment for those too ignorant do basic
IEOR calculations.

Running either tractor wide open to work a square mile at 0.5 mph
would take 3 months of 7 day work weeks at 8 hours / day.

It would also require 17,000 gallons of diesel.

Today the cost is "only" $80,000 for the diesel.

In 2 years, with the price of hydrocarbon fuel spiraling by 30% a
year, that cost will be $150,000/yr.

In six years the cost of the fuel will be half a million dollars.

And that's just for one field.

Maybe if we have massive truck and bus conversion to natural gas --
include farm tractors in Pickens plan -- the price will "only" be
$350,000/field in 6 years.

The battery tractor would be cheaper even if grid power tripled and
even if you went to your overpriced Apple Inc. store and bought the
batteries one by one and wired them together one by one yourself.

Now, if you don't believe laptop batteries exist, please go to alt.
conspiracy and post there.

Bret Cahill

I've read that over time, crop fields suffer from the compression of
tractor wheels.

Would it make sense, for heavily utilised fields, to lay down a rail
track?

Whatever the tractor / harvester is doing, it could be a 20m wide
vehicle necessitating a single track spaced every 20m.

The track could also be used to provide electric power.

A few details to work out about how the tractor changes track at the
end of the rails.

 

[John Larkin]

On Fri, 25 Jul 2008 15:17:58 -0700 (PDT), disgoftunwells
<disgoftunwells@yahoo.co.uk> wrote:

On 23 Jul, 23:03, BretCah...@peoplepc.com wrote:
The Tesla is powered by 7,000 Li-Ion laptop batteries for an output of
200 kW.

A similarly powered 300 kW electric tractor (10,500 batteries) would
turn a 400 hp articulated 22 gallon/hour diesel tractor every which
way but loose in a tractor pull which apparently is vitally necessary
education as well as entertainment for those too ignorant do basic
IEOR calculations.

Running either tractor wide open to work a square mile at 0.5 mph
would take 3 months of 7 day work weeks at 8 hours / day.

It would also require 17,000 gallons of diesel.

Today the cost is "only" $80,000 for the diesel.

In 2 years, with the price of hydrocarbon fuel spiraling by 30% a
year, that cost will be $150,000/yr.

In six years the cost of the fuel will be half a million dollars.

And that's just for one field.

Maybe if we have massive truck and bus conversion to natural gas --
include farm tractors in Pickens plan -- the price will "only" be
$350,000/field in 6 years.

The battery tractor would be cheaper even if grid power tripled and
even if you went to your overpriced Apple Inc. store and bought the
batteries one by one and wired them together one by one yourself.

Now, if you don't believe laptop batteries exist, please go to alt.
conspiracy and post there.

Bret Cahill

I've read that over time, crop fields suffer from the compression of
tractor wheels.

Would it make sense, for heavily utilised fields, to lay down a rail
track?

Whatever the tractor / harvester is doing, it could be a 20m wide
vehicle necessitating a single track spaced every 20m.

The track could also be used to provide electric power.

A few details to work out about how the tractor changes track at the
end of the rails.

Why not monorails in all the cornfields? Then the electric power
could be provided by the rail, and there would be zero unnecessary
contact with the soil. And you could give tourists rides in the off
season.

Or just use nuclear powered helicopters for plowing; as a bonus,
they'd blow the bugs away, and irradiate the produce.

I you bury superconductors under the crop rows, you could use a maglev
tractor. Put Luke Skywalker back on the farm.

Or the San Francisco farming technique, cable-car tractors. No power
needed at all!

We'll teach all those dumb farmers how to do it right.

John

 

[Eeyore]

"Paul E. Schoen" wrote:

"John Fields" <jfields@austininstruments.com> wrote in message
"Rob Dekker" <rob@verific.com>> wrote:
"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message
"Paul E. Schoen" wrote:

Losses are always part of the equation, but a reasonably well
engineered
system might be rather efficient even using "low voltage" cable. For
something like 90 HP, or 66 kW, a three phase 480 VAC supply at 80
amps per
phase could use #2 portable cordage.

OK, but how long will that cable last being dragged around a field with
sharp
stones, even if one of the tractor attachments doesn't sever it just
for good
measure ? Arken Sparken time !

Yes. That would be crazy.


Sorry, but it sounds like one of the most utterly insane ideas ever
from basic
principles.

Basic principles ?

---
Sticks and stones may break my ohms...

But words never Hertz me...

The cable needs to be rolled and unrolled on the center pivot beam, so it
never even touches the ground. The tractor can support part of the beam and
can pivot at various angles so it can traverse the field with some freedom
of motion, but its best path will be concentric circles. It will be some
tricky engineering to allow the tractor to pass the other support/drive
wheels for the beam, but challenges like that are what make engineering
fun.

Sharp intake of breath.

But not always possible. I mean what grade of sheath wouls such a cable require
? And concentric circles IS NOT how farmers like to work fields for what I hope
are obvious reasons. How about the getting into the 'corners' ?

Graham

 

[Eeyore]

Rob Dekker wrote:

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote
Rob Dekker wrote:

As long as they stay withing reasonable limits. Which should be OK for (standard)

11kV AC distribution power line and a few miles
of cable.

You're thinking of using 11kV flexible cable (what happens to 'erosion' of the insulation > btw ?) miles long in junction with
agricultural equipment designed to cut through > anything like that.

Yes.

You're certifiably mad.

Hardly ever mad. Crazy sometimes, but only for fun.

Flexible high-voltage cables....
Do you want me to select one for you from a catalog ?
http://www.thomasnet.com/products/cable-assemblies-coaxial-high-voltage-9634304-1.html

In ardous duty rough terrain whilst being regularly flexed ? I suggest you look up the specs.

Hey, I'll give you 'neat idea' tick bit I cannot for the life of me ever see it being engineeringly practical (not to mention killing
thousands of farm workers every year too).

Graham

 

[Eeyore]

John Fields wrote:

Bret Cahill <BretCahill@aol.com> wrote:

Losses aren't an issue.

---
So, you don't know anything about electrical power distribution
either?

Buffoon, losses are_always_ an issue.

Why else do you think long-haul transmission lines use high voltages
to move electricity around?

It's just for fun isn't it John ? Those HV guys love having a
giggle. ;~)

Graham

 

[Eeyore]

"Paul E. Schoen" wrote:

"John Fields" wrote

Sticks and stones may break my ohms...

But words never Hertz me...

We need an archive of great quotes for such gems.

Graham

 

[Eeyore]

John Larkin wrote:

disgoftunwells wrote:
OBretCah...@peoplepc.com wrote:
The Tesla is powered by 7,000 Li-Ion laptop batteries for an output of
200 kW.

A similarly powered 300 kW electric tractor (10,500 batteries) would
turn a 400 hp articulated 22 gallon/hour diesel tractor every which
way but loose in a tractor pull which apparently is vitally necessary
education as well as entertainment for those too ignorant do basic
IEOR calculations.

Running either tractor wide open to work a square mile at 0.5 mph
would take 3 months of 7 day work weeks at 8 hours / day.

It would also require 17,000 gallons of diesel.

Today the cost is "only" $80,000 for the diesel.

In 2 years, with the price of hydrocarbon fuel spiraling by 30% a
year, that cost will be $150,000/yr.

In six years the cost of the fuel will be half a million dollars.

And that's just for one field.

Maybe if we have massive truck and bus conversion to natural gas --
include farm tractors in Pickens plan -- the price will "only" be
$350,000/field in 6 years.

The battery tractor would be cheaper even if grid power tripled and
even if you went to your overpriced Apple Inc. store and bought the
batteries one by one and wired them together one by one yourself.

Now, if you don't believe laptop batteries exist, please go to alt.
conspiracy and post there.

Bret Cahill

I've read that over time, crop fields suffer from the compression of
tractor wheels.

Would it make sense, for heavily utilised fields, to lay down a rail
track?

Whatever the tractor / harvester is doing, it could be a 20m wide
vehicle necessitating a single track spaced every 20m.

The track could also be used to provide electric power.

A few details to work out about how the tractor changes track at the
end of the rails.

Why not monorails in all the cornfields? Then the electric power
could be provided by the rail, and there would be zero unnecessary
contact with the soil. And you could give tourists rides in the off
season.

Or just use nuclear powered helicopters for plowing; as a bonus,
they'd blow the bugs away, and irradiate the produce.

I you bury superconductors under the crop rows, you could use a maglev
tractor. Put Luke Skywalker back on the farm.

Or the San Francisco farming technique, cable-car tractors. No power
needed at all!

We'll teach all those dumb farmers how to do it right.

When I read the first line of your post, for a second I wondered in you'd had
some psychotic episode.

Graham

 

[terryc]

On Sat, 26 Jul 2008 02:17:42 +0100, Eeyore wrote:

Hey, I'll give you 'neat idea' tick bit I cannot for the life of me ever see it being engineeringly practical (not to mention killing
thousands of farm workers every year too).

something much worse. Ever been down an underground mine with electrically
operated shuttle cars.

""Make sure that when ever you have to cross a shuttle car cable that you
step onto the cable and not over it"
Why?
"You don't want to know"

 

[terryc]

On Sat, 26 Jul 2008 02:13:15 +0100, Eeyore wrote:

But not always possible. I mean what grade of sheath wouls such a cable require

Stuff would already exist in the mining industry. The farmer would just
need a crane to connect and disconnect it. It is the rotating multipole
connector that has me intrigued

? And concentric circles IS NOT how farmers like to work fields for what I hope
are obvious reasons. How about the getting into the 'corners' ?

He is avoiding all those problems by talking about mythical flat land
where you do not have corners in irrigation bays, etc.

 

[Day Brown]

Might wanna take a look at http://daybrown.org/farmath/farmath.html
A team of oat burners will pull a moldboard plow at 5mph, covering about
7.5 acres/day. Mite try 3 oxen with a double bottom at 3mph, but get
10 acres/day. And oxen dont need oats.

If the proverbial schitt hits the fan, I'm gonna walk into a pasture
with a hatfull of corn, and walk out with oxen following me cause they
dont mind me stroking them while they eat, and they want more.

There are also horses that still have the full set of instincts to be
worked as draft animals. Right now, one farmer grows enuf food for 100
people. With draft animals, one feeds 25. That's still not that bad, and
its a system that has worked for thousands of years.

With diesel and petrochemicals, they expect 155 bu corn/acre. Farmath,
in 1885, got only 21 bu corn. But, I was born on a farm, and remember
draft animals getting 45-48 bu/acre with what we now call 'organic'
methods using better hybrid seed. And it aint that hard to produce the
hybrid seed with organic methods.

BTW: a problem with the high density NiMH is that you can fuck them up
if they are not charged at the right rate and then turned off. The
technology with draft animals could be looked into to dramatically
improve production.

Worth considering also is using 3.5 gallons of tractor fuel to grow
sorghum, which will produce 100-120 gallons of ethanol, which can then
be converted into butanol. Which will run any gas engine without any
modification at the same power output.

 

[John Larkin]

On Sat, 26 Jul 2008 02:47:35 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

John Larkin wrote:

disgoftunwells wrote:
OBretCah...@peoplepc.com wrote:
The Tesla is powered by 7,000 Li-Ion laptop batteries for an output of
200 kW.

A similarly powered 300 kW electric tractor (10,500 batteries) would
turn a 400 hp articulated 22 gallon/hour diesel tractor every which
way but loose in a tractor pull which apparently is vitally necessary
education as well as entertainment for those too ignorant do basic
IEOR calculations.

Running either tractor wide open to work a square mile at 0.5 mph
would take 3 months of 7 day work weeks at 8 hours / day.

It would also require 17,000 gallons of diesel.

Today the cost is "only" $80,000 for the diesel.

In 2 years, with the price of hydrocarbon fuel spiraling by 30% a
year, that cost will be $150,000/yr.

In six years the cost of the fuel will be half a million dollars.

And that's just for one field.

Maybe if we have massive truck and bus conversion to natural gas --
include farm tractors in Pickens plan -- the price will "only" be
$350,000/field in 6 years.

The battery tractor would be cheaper even if grid power tripled and
even if you went to your overpriced Apple Inc. store and bought the
batteries one by one and wired them together one by one yourself.

Now, if you don't believe laptop batteries exist, please go to alt.
conspiracy and post there.

Bret Cahill

I've read that over time, crop fields suffer from the compression of
tractor wheels.

Would it make sense, for heavily utilised fields, to lay down a rail
track?

Whatever the tractor / harvester is doing, it could be a 20m wide
vehicle necessitating a single track spaced every 20m.

The track could also be used to provide electric power.

A few details to work out about how the tractor changes track at the
end of the rails.

Why not monorails in all the cornfields? Then the electric power
could be provided by the rail, and there would be zero unnecessary
contact with the soil. And you could give tourists rides in the off
season.

Or just use nuclear powered helicopters for plowing; as a bonus,
they'd blow the bugs away, and irradiate the produce.

I you bury superconductors under the crop rows, you could use a maglev
tractor. Put Luke Skywalker back on the farm.

Or the San Francisco farming technique, cable-car tractors. No power
needed at all!

We'll teach all those dumb farmers how to do it right.

When I read the first line of your post, for a second I wondered in you'd had
some psychotic episode.

I have psychotic episodes daily, or more often for difficult projects.

Often we'll go into the conference room and do it as a departmental
activity. The whiteboards get positively psychedelic.

Bret has two problems: he's fixated on a single solution, and he
understands neither the application nor the technology. He's crazier
than I am.

What farmers really need are robot oxen.

John

 

[John Larkin]

On Sat, 26 Jul 2008 14:39:03 -0700 (PDT), Bret Cahill
<BretCahill@aol.com> wrote:

Losses aren't an issue.

. . .

Why else do you think long-haul transmission lines use high voltages
to move electricity around?

Because they are long haul, over a hundred miles in many cases. The
quarter square tractor trolly line only needs to go half a mile.

Half a mile from where? An electrical outlet conveniently located in
the middle of 800 acres of corn field?

Are you just acting dumb or are you really this stupid in real life?

Please refresh us on your background in electrical engineering, and in
farming.

John

 

[Bret Cahill]

Losses aren't an issue.

.. . .

Why else do you think long-haul transmission lines use high voltages
to move electricity around?

Because they are long haul, over a hundred miles in many cases. The
quarter square tractor trolly line only needs to go half a mile.

Are you just acting dumb or are you really this stupid in real life?


Bret Cahill

 

[Bret Cahill]

Losses aren't an issue.

I just love the stuff you come up with !

Graham

I'd like to know what he thinks losses are.

Losses are always part of the equation, but a reasonably well engineered
system might be rather efficient even using "low voltage" cable. For
something like 90 HP, or 66 kW, a three phase 480 VAC supply at 80 amps per
phase could use #2 portable cordage. A 250 foot length is $14.49/ft, so you
are looking at a capital outlay of $3600 to allow the tractor to traverse a
circular field of 200,000 square feet, or about 5 acres. It would need to
be stowed on the tractor on a reel, and supported to its central connection
point on a pivot arm. This #2 cable has a resistance of 156 uOhms per foot,
so at 80 amps it will drop 3.12 volts out of 277, or roughly 1% loss. Even
a 1000 ft cable would still have acceptable losses, compared to efficiency
of the electric motor and distribution transformer at the central supply
point.

For higher HP ratings, multiple cables could be used, but I think a 90 HP
electric tractor is probably equivalent to a a 150 HP diesel, and you just
need to look at actual needs of torque and speed, which determine the HP
required.

There will probably be more losses with a hybrid system that uses 8000
batteries or the equivalent in battery packs. A mostly grid-powered system
is feasible using current technology, and should reap almost immediate cost
savings, or ROI within a few years.

But every objection to a proposed improvement is just an engineering
challenge that promotes thought and new ideas that can be shown to address
the problems and provide a workable solution. Almost every new technology
seems to be impractical or awkward in its infancy, but innovation prevails,
and changing economic realities make the future a different place.

Well we know oil is spiraling and we know and PV is going down in
cost. We also know that batteries are continually improving. If not
now then well before the first prototype electric field tractor ever
appears it will _already_ be cost effective in most regions.

Having a source of power that is always very close to a moving
electric motor means even low power density storage devices such as
compressed air, flywheels or capacitors might be considered within
reach.

This is the real advantage of electric tractors over hybrid road
vehicles.

Yet I can see that much of this discussion has degraded to a battle among
several narrow-minded viewpoints, and that will serve no useful purpose.

The real problems to be solved are either identical to the hybrid or
EV, i. e., cheap good battery, a materials problem, or unique to
argicultural operations, i. e., electric power is always within a
relatively short distance of the tractor or some combination those
two.

Everything else is white noise.


Bret Cahill

 

[Bret Cahill]

The cable needs to be rolled and unrolled on the center pivot beam, so it
never even touches the ground.

Strip mine excavators roll a 6" thick insulated cable on the ground
from a spool mounted on the excavator.

The excavator moves very slowly and only makes one pass or so over the
ground, however.

The tractor can support part of the beam and
can pivot at various angles so it can traverse the field with some freedom
of motion, but its best path will be concentric circles. It will be some
tricky engineering to allow the tractor to pass the other support/drive
wheels for the beam, but challenges like that are what make engineering
fun.

The fastest cheapest easiest _prototype_ to get your foot into the
door would be the battery-trolly line. If a cheap battery didn't
appear in time, then the system would be abandoned at the state U's
extension research farm.

After that then maybe it will be possible to talk farmers into
screwing around with a lot of wires and Rube Goldberg kinematics.


Bret Cahill

 

[Bret Cahill]

But not always possible. I mean what grade of sheath wouls such a cable
require

Stuff would already exist in the mining industry. The farmer would just
need a crane to connect and disconnect it. It is the rotating multipole
connector that has me intrigued

? And concentric circles IS NOT how farmers like to work fields for what
I hope
are obvious reasons. How about the getting into the 'corners' ?

He is avoiding all those problems by talking about mythical flat land
where you do not have corners in irrigation bays, etc.

Guys, show a little bit of imagination and engineering inginuity please.
After all, we wanted to get rid of the battery idea (gaining efficiency, and
most of all difficult recharges).

The cable can be suspended far over ground close to the tractor (away from
the moving parts), maybe even all the way across the field using a system of
overhead arms or small computer-controlled robot 'cable-suspension' cars.

A rotating multipole connecter should not be needed : a 1/2 mile cable can
handle a few 180's.

Even high tension towers are only spaced 1/4 mile apart. I use them
to triangulate my distance cycling.

On a battery basis, 1/2 a mile is a short distance. On a cable basis
it's a long distance.

Also, the time is here that plowing (or seeding or so) no nonger needs a
human on the tractor. Much is being computerized, running the tractor on
pre-programmed patterns using GPS and such, so that effiency is maximized.
Even work at night is then possiible (which also reduces the machinery
deficit that seems to plague harvest time). So, you can simply program the
pattern so that 'twisting' the wire is not an issue.

The fastest cheapest easiest _prototype_ to get your foot into the
door would be the battery-trolly line. If a cheap battery didn't
appear in time, then the system would be abandoned at the state U's
extension research farm.

After that then maybe it will be possible to talk farmers into
screwing around with a lot of wires and Rube Goldberg kinematics.


Bret Cahill