Breaking hard ground with motors

[nduka-san]

TL;DR

im trying to find a motor that will break hard ground

I'm trying to find a motor that would break hard ground what would you recommend, here is my research so far:
My research is based on horsepower its bad research but I thought it might apply to a motor since its s
also this is under the asumption of a 3 pound hoe
people managed to do a lot of farming with a horse. All that plowing and tilling and stuff.

Well, a horse puts out one horsepower which is 745.7 watts. Let's call that 1KW. I'm rounding up just easier calculations

Such an electric motor might run from 50v or so. So the battery pack will have to deliver 20 amps. and if I want it to run for a full workday(8 hours ), I need a battery that can store 160 amps and deliver 20 amps per hour

 

[Mark44]

Summary:: I am trying to find a motor that will break hard ground

I'm trying to find a motor that would break hard ground what would you recommend, here is my research so far:
My research is based on horsepower its bad research but I thought it might apply to a motor since its s
also this is under the asumption of a 3 pound hoe
people managed to do a lot of farming with a horse. All that plowing and tilling and stuff.

Well, a horse puts out one horsepower which is 745.7 watts. Let's call that 1KW. I'm rounding up just easier calculations

Such an electric motor might run from 50v or so. So the battery pack will have to deliver 20 amps. and if I want it to run for a full workday(8 hours ), I need a battery that can store 160 amps and deliver 20 amps per hour

I don't see why such a motor would necessarily need to run at 50 V.
Have you done any research on car batteries?
One car battery I looked at is 12 V, with a reserve capacity (RC) of 110 minutes, or just under two hours. One site defines the term "reserve capacity" as

a general indicator of how long a new, fully charged battery can continue to operate essential accessories if the vehicle’s alternator fails. It identifies how many minutes the battery can deliver a constant current of 25 amps at 80°F without falling below the minimum voltage, 1.75 volts per cell, needed to keep your vehicle running.

 

[nduka-san]

No i didnt but let me go look for some and ill return with some new research

 

[Vanadium 50]

First, please write in sentences. You've been asked nicely by my count no fewer than eight times. Your very first sentence is a run-on. If we were to respond with giant run-on sentences, you'd complain, wouldn't you?

Second, finding an engine that is used to operate a roto-tiller took literally five seconds with Google. Once I knew that, finding an electric motor with the same power and RPM took another five seconds.

If you're going to object with "Yes, but how do you expect me to know that the thing that does this is called a roto-tiller?" my answer would be that's why I suggested you read a book on farming. Before you can devise a plan to learn how to do it better, you need to know how they do it now.

If you did these two sentences, you would have found that roto-tillers use substantially more power. More like 5 kW rather than 1 kW. There are some cordless ones (five more seconds searching) in the 1 kW range but they are smaller than what is usually used in gardening, and MUCH smaller than what is used in farming. Their batteries run the tiller for around half an hour and cost $179.99 (another five seconds). So if you want eight hours of continuous use, you need almost $3000 in batteries alone.

 

[russ_watters]

I'm trying to find a motor that would break hard ground

A motor won't break hard ground unless you throw it or shoot it at the ground. Motors just spin things. It's the thing the motor spins that breaks the ground. So you first need to figure out what thing that breaks the ground is, that you want to spin. A roto-tiller? A motorized plow? A seed injector? An aerater?

And how much, how deep and how fast.

 

[nduka-san]

A motor won't break hard ground unless you throw it or shoot it at the ground. Motors just spin things. It's the thing the mot So you first need to figure out what thing that breaks the ground is, that you want to spin. A roto-tiller? A motorized plow? A seed injector? An aerater?

And how much, how deep and how fast.

I was aiming for 6 inches deep.
The thing that I want to spin is a detachable hoe with a weight of 3 pounds, the length of the rod is 2 feet. The robot is a metal cube 2ft by 2ft so that it touches the ground while moving on farmland.
I was assuming a speed of 5 mph.

Edit here's a motor i was considering
https://hobbyking.com/en_us/turnigy-sk8-6354-200kv-sensored-brushless-motor-14p.html

 

[Averagesupernova]

You are sooo in over your head. You have the motivation but nothing to back it. Where are you getting 5 MPH from? Tillage is an energy intense operation and 5 MPH is clipping along. I'm sorry if we come off sounding like we are just trying to hammer you into the ground, but nature is not forgiving. If you don't have everything right, your endeavors will fail.

 

[Vanadium 50]

Where are you getting 5 MPH from? Tillage is an energy intense operation and 5 MPH is clipping along.

It's also in the wrong units. The relevant units are area per unit time, not linear distance per unit time.

 

[Dullard]

Not to pile on, but:

A horse can make '1 horsepower' all day long. He can make a lot more than 1 HP (instantaneously) when properly encouraged.

 

[Averagesupernova]

Depending on the type of tillage done, there is a lower limit on speed as well as an upper limit. The op doesn't likely realize that breaking sod takes a form of tillage that would be different than say tilling after a previous crop. My guess is that any farming done in the country in question is done by farmers that could teach the op a thing or two. The place to start is to look at how it is being done now and look for improvements that give the most bang for the buck.

 

[jbriggs444]

I need a battery that can store 160 amps and deliver 20 amps per hour

An "amp" is a measure of current flow. Charge per unit time.

You want a battery that can delivery 20 amps for 8 hours. That is 160 amp-hours.

Alternately (though no one actually uses these units for this purpose), you want a battery that can deliver 20 coulombs per second for 8 hours. That means that must be able to deliver 576,000 coulombs of charge.

It sounds like the design is a device that works like and is sized similar to the hand tool known as a "mattock". Such devices are suitable to a pace of perhaps 1/2 inch per second -- paced to the rhythm of a sea chanty or a chain-gang song. Faster than that and you're running into tipping problems with high applied torque rather than letting gravity swing the blade for you.

I know that I wouldn't want to take more than about a 2 inch bite at a 4 second cycle if I were swinging the thing. More than two inches and the ground doesn't have enough "give". It'll resist the penetration instead of flaking off nicely. [At that cycle rate, I'd be gasping for breath after about 60 seconds].

Experience wielding a shovel and a hoe provide some clues for this sort of thing.

 

[russ_watters]

My guess is that any farming done in the country in question is done by farmers that could teach the op a thing or two.

One might even look to a farming forum for knowledge and advice...

 

[Averagesupernova]

One might even look to a farming forum for knowledge and advice...

He will get laughed off the internet.

 

[hutchphd]

Would it not be kind to end this farce? (And all subsequent farces)

 

[Averagesupernova]

It was be nice if something would sink in before another is killed off.

 

[hmmm27]

Make a solar-powered pyrolizer for the remnants of the previous year's crops. Use the producer gas to power a real tractor ; turn the leftover carbon/etc back into the soil.

Check a farming site, though - removing the detritus and its attendant helpful bacteria might not be a good idea.

 

[Dale]

So my tractor is a small 22 hp tractor. With the right attachment I could till a 48” plot to a good depth. We have hard clay here, and that can bog it down and prevent much depth. We also have lots of subsurface roots which can jam it frequently.

 

[Vanadium 50]

Spring - the time to till
Brand new robotic tiller
The battery dies

 

[nduka-san]

One might even look to a farming forum for knowledge and advice...

I did they gave me this advice:
R x e(3cp - 4n) = y2/65 where R = Robot and cp is the terminal velocity of the robots spade.
read this article:https://journals.ashs.org/horttech/view/journals/horttech/27/6/article-p746.xml
add some graphs to your proposal

 

[jbriggs444]

I did they gave me this advice:
R x e(3cp - 4n) = y2/65 where R = Robot and cp is the terminal velocity of the robots spade.
read this article:https://journals.ashs.org/horttech/view/journals/horttech/27/6/article-p746.xml
add some graphs to your proposal

As it stands, that formula is gibberish. If R is "Robot" then R is not a numeric quantity. We are left to guess what e, n and y2 are supposed to denote. The idea that someone mathematically literate put the formula together is ludicrous because a mathematician would know not to use two-letter variable names when multiplication is indicated by juxtaposition.

An engineer or a physicist would have provided units of measure.

 

[nduka-san]

An "amp" is a measure of current flow. Charge per unit time.

You want a battery that can delivery 20 amps for 8 hours. That is 160 amp-hours.

Alternately (though no one actually uses these units for this purpose), you want a battery that can deliver 20 coulombs per second for 8 hours. That means that must be able to deliver 576,000 coulombs of charge.

It sounds like the design is a device that works like and is sized similar to the hand tool known as a "mattock". Such devices are suitable to a pace of perhaps 1/2 inch per second -- paced to the rhythm of a sea chanty or a chain-gang song. Faster than that and you're running into tipping problems with high applied torque rather than letting gravity swing the blade for you.

I know that I wouldn't want to take more than about a 2 inch bite at a 4 second cycle if I were swinging the thing. More than two inches and the ground doesn't have enough "give". It'll resist the penetration instead of flaking off nicely. [At that cycle rate, I'd be gasping for breath after about 60 seconds].

Experience wielding a shovel and a hoe provide some clues for this sort of thing.

Thank you for your advice.
Can i send you my design sketches so you can review them?
Also would it be appropriate for this thread?
if not could i rename the thread

 

[nduka-san]

Spring - the time to till
Brand new robotic tiller
The battery dies

What size battery would you recommend then?

 

[jbriggs444]

Can i send you my design sketches so you can review them?

Not by private message, no.

However, a design more precise than "two foot rod", "three pound hoe", "five miles per hour", "two foot cube" and "six inch depth" would be easier to talk about and evaluate against a claim of 1000 watts.

 

[nduka-san]

Not by private message, no.

May i attatch them here?

 

[Vanadium 50]

What size battery would you recommend then?

As big as it needs to be.

 

[jbriggs444]

As big as it needs to be.

And no bigger than one has the ability to house and support. A goal is to arrange matters so that the solution set is non-empty.

 

[nduka-san]

Quick question, Would you recommend Aluminium or stainless steel. I'm asking because I'm filling out the price chart and resizing some parts and sketches. The lifespan of the robot is supposed to last a decade.

Current research: Some stainless steel can last 30 years

 

[Vanadium 50]

When you ask that, people are likely to conclude that you are not being serious.

 

[nduka-san]

When you ask that, people are likely to conclude that you are not being serious.

I'm just asking their opinion because I have never handled aluminum or stainless steel in robotics. I usually use wood or plastic bases for my robots.
PS: the proper term is aren't

 

[jbriggs444]

PS: the proper term is aren't

Are you contending that the use of the contraction "aren't" is proper while the full form "are not" is not?

Shirly you can't be serious.