What is the Pull Strength of a 48v Battery on a 1.5 Ton Weight with DC Power?

[ChaserNZ]

I know there have been discussions on electromagnets, but I think my question here is specific and hopefully quite different. Using DC power only, what amount of pull might I expect from, let's say, 48v of decent lead acid battery or batteries? It occurs to me that one could use an ebike battery of 48v? In case it is required information, let's say that pull is being exerted on a ton and a half weight from, say, 20ft? By all means hit me with clarification needs! I'm new here and not overly scientifically minded. Inventive yes, genius not so much

 

[berkeman]

I know there have been discussions on electromagnets, but I think my question here is specific and hopefully quite different. Using DC power only, what amount of pull might I expect from, let's say, 48v of decent lead acid battery or batteries? It occurs to me that one could use an ebike battery of 48v? In case it is required information, let's say that pull is being exerted on a ton and a half weight from, say, 20ft? By all means hit me with clarification needs! I'm new here and not overly scientifically minded. Inventive yes, genius not so much

Welcome to the PF.

At 20 feet, not much. At something like one foot of separation, you will get a pretty substantial force. But that force is not going to accelerate 1.5 tons very quickly (even with zero friction to overcome). What is the application?

https://en.wikipedia.org/wiki/Electromagnet

 

[SleepDeprived]

I know there have been discussions on electromagnets, but I think my question here is specific and hopefully quite different. Using DC power only, what amount of pull might I expect from, let's say, 48v of decent lead acid battery or batteries? It occurs to me that one could use an ebike battery of 48v? In case it is required information, let's say that pull is being exerted on a ton and a half weight from, say, 20ft? By all means hit me with clarification needs! I'm new here and not overly scientifically minded. Inventive yes, genius not so much

Your question may lack some specifics but in general, the "pull" that you mention I take that it means "power" or how much work can be done given a specific time.
Battery power can be measured in how much current it can discharge. For example, if the 48V battery can discharge 10A at any given time, then it can do 48V * 10A = 480W or it can do 480 Joules/sec. My basic physics a bit hazy so I guess you can find an equation to calculate how fast you can accelerate a 1.5Ton object with 480W of power. But guess there are other factors such as frictions, gearing, ... that not specified in your questions.

 

[berkeman]

Your question may lack some specifics but in general, the "pull" that you mention I take that it means "power" or how much work can be done given a specific time.
Battery power can be measured in how much current it can discharge. For example, if the 48V battery can discharge 10A at any given time, then it can do 48V * 10A = 480W or it can do 480 Joules/sec. My basic physics a bit hazy so I guess you can find an equation to calculate how fast you can accelerate a 1.5Ton object with 480W of power. But guess there are other factors such as frictions, gearing, ... that not specified in your questions.

That's not a good approach, IMO. Who cares if the coil around the electromagnet dissipates 480W through resistive losses? That has nothing to do with any attractive force and the work done via it.

 

[SleepDeprived]

That's not a good approach, IMO. Who cares if the coil around the electromagnet dissipates 480W through resistive losses? That has nothing to do with any attractive force and the work done via it.

Hm... I thought the OP was asking how much his 1.5Ton object can be "pull" by using a 48V pack. I am not sure what you referred to in your post such as electromagnetic and resistive losses had anything to do with my post? I was simply trying to refer how much his 1.5Ton can be pulled by the power of a 48V pack.

 

[berkeman]

Hm... I thought the OP was asking how much his 1.5Ton object can be "pull" by using a 48V pack. I am not sure what you referred to in your post such as electromagnetic and resistive losses had anything to do with my post? I was simply trying to refer how much his 1.5Ton can be pulled by the power of a 48V pack.

Have you read through the wi,kipedia link that I posted on this topic for the OP?

How much experience to you have with force and work done by electromagnets? We appreciate you trying to help with questions here. Please be sure to do the research before replying. Thanks.

 

[SleepDeprived]

Have you read through the wi,kipedia link that I posted on this topic for the OP?

How much experience to you have with force and work done by electromagnets? We appreciate you trying to help with questions here. Please be sure to do the research before replying. Thanks.

oops, sorry, I was trying to answer a different question. I mean the OP could be more specific by saying he is trying to calculate the electromagnetic force induced by using a solenoid (at least I think that is the intent of the question). I thought he was asking about how fast a car with 1.5T weight can be accelerate using 48V battery pack. That's why I mention fiction and gearing.

 

[ChaserNZ]

That's not a good approach, IMO. Who cares if the coil around the electromagnet dissipates 480W through resistive losses? That has nothing to do with any attractive force and the work done via it.

Seems good value in the answers of both you and Sleepdeprived. Given my notion that an ebike lead acid battery could be the pwer source, I don't see why seventytwo volt battery couldn't be the power for the electromagnet. If so, could the pull on a ton and a half object not be reasonable at, say, ten feet? Sorry I can't yet entirely give away the reasons for my queries

 

[ChaserNZ]

Your question may lack some specifics but in general, the "pull" that you mention I take that it means "power" or how much work can be done given a specific time.
Battery power can be measured in how much current it can discharge. For example, if the 48V battery can discharge 10A at any given time, then it can do 48V * 10A = 480W or it can do 480 Joules/sec. My basic physics a bit hazy so I guess you can find an equation to calculate how fast you can accelerate a 1.5Ton object with 480W of power. But guess there are other factors such as frictions, gearing, ... that not specified in your questions.

Does it make any difference that I am looking to decelerate the object rather than accelerate. To pull said object toward the electromagnet. I thought that was the usual intent?

 

[SleepDeprived]

Sorry I can't yet entirely give away the reasons for my queries

I have to say that is a very odd question. What is it that you're trying to pull? By what mechanism -- I assume some type of electromagnetic force but could you be more specific? Based on your description, I mean it could be anything. Sorry if I am being a bit blunt. I am not quite as polish as some of the participants here.

 

[berkeman]

could the pull on a ton and a half object not be reasonable at, say, ten feet?

No way. Did you read the wikipedia link that I posted?

 

[ChaserNZ]

Have you read through the wi,kipedia link that I posted on this topic for the OP?

How much experience to you have with force and work done by electromagnets? We appreciate you trying to help with questions here. Please be sure to do the research before replying. Thanks.

Yes, indeed I looked up the Wikipedia link you posted. That confirmed for certain that I'm no scientist! It appeared that much of the data was written with the notion that the reader would be making ones own electromagnet. Hell may freeze over before that happens, but I assume there are myriad electromagnets available that one can purchase, once an understanding of the unit's ability for my application is established. Fortunately, it seems many here have ideas about electromagnets ability - voltage, pull etc. Given my aim, any and all info appreciated

 

[berkeman]

Yes, indeed I looked up the Wikipedia link you posted. That confirmed for certain that I'm no scientist! It appeared that much of the data was written with the notion that the reader would be making ones own electromagnet. Hell may freeze over before that happens, but I assume there are myriad electromagnets available that one can purchase, once an understanding of the unit's ability for my application is established. Fortunately, it seems many here have ideas about electromagnets ability - voltage, pull etc. Given my aim, any and all info appreciated

And the quantitative section of that wikipedia article did not help you in your calculations?

Maybe your focus on Homeopathy mentioned in your Profile page is hindering your quantitative analysis...

 

[ChaserNZ]

No way. Did you read the wikipedia link that I posted?

Surely, the voltage, the amps, play a large part n the ability to decelerate a ton and a half weight, of steel I might add. I am just trying to figure why you said No way. As. I say, I did read your Wikipedia link. But yes, it was heavy going for me.

 

[ChaserNZ]

And the quantitative section of that wikipedia article did not help you in your calculations?

Maybe your focus on Homeopathy mentioned in your Profile page is hindering your quantitative analysis...

No bloody way. Why shouldn't I add quantitative analysis and simply electromagnetic study to my life? My questions are not burn of minor amusement, rather intense interest in a new topic in my life, and plan to use what I learn for a serious purpose.

 

[berkeman]

Surely, the voltage, the amps, play a large part n the ability to decelerate a ton and a half weight, of steel I might add. I am just trying to figure why you said No way. As. I say, I did read your Wikipedia link. But yes, it was heavy going for me.

Well, when you watch YouTube videos of practical working electromagnets that lift cars off the ground using thousands of amps and much more power than your question involves, what is the typical distance that is used to start the lifts...?

 

[davenn]

Well, when you watch YouTube videos of practical working electromagnets that lift cars off the ground using thousands of amps and much more power than your question involves, what is the typical distance that is used to start the lifts...?

yep ... I was thinking of asking the same thing with the huge electromagnets in scrap metal yards

Dave

 

[Baluncore]

The magnetic field will prefer to pass a few feet through the air between the electromagnet's poles, rather than 20 feet to the steel and then 20 feet back again. Once a magnetic circuit is formed, the attraction results in the field lines shortening. The fundamental problem here is that the 1.5 tonnes of steel will need to get across, or between the poles of the magnet, or it will not become part of the magnetic circuit.

 

[ChaserNZ]

The magnetic field will prefer to pass a few feet through the air between the electromagnet's poles, rather than 20 feet to the steel and then 20 feet back again. Once a magnetic circuit is formed, the attraction results in the field lines shortening. The fundamental problem here is that the 1.5 tonnes of steel will need to get across, or between the poles of the magnet, or it will not become part of the magnetic circuit.

Fair point, reflects the fact I am no physics expert. But what I lean toward is that scrap metal yards surely get past this issue, but how? And with what wattage/amperage? Either way, my application has to be DC powered.

 

[berkeman]

Fair point, reflects the fact I am no physics expert. But what I lean toward is that scrap metal yards surely get past this issue, but how? And with what wattage/amperage? Either way, my application has to be DC powered.

One of the ways that they maximize the magnetic "pulling/lifting" force is to keep the magnetic path length (thorough the air) short, as Baluncore said. If you look at the lifting electromagnets in those high-force applications, you'll see magnet structures like coaxial cylinders. So the two poles of the magnet are coaxial and the faces are close together. That makes for a very small magnetic path through the air to capture the load and lift it.

A horseshoe magnet is similar -- the distance from one pole to the other is small magnetically when the two tips of the horseshoe are brought close to the ferrous metal target (car or scrap metal or whatever).

https://s-media-cache-ak0.pinimg.com/originals/59/3e/76/593e76d79b7dcb43c8065d5a1535413a.jpg

 

[Baluncore]

But what I lean toward is that scrap metal yards surely get past this issue, but how? And with what wattage/amperage? Either way, my application has to be DC powered.

At the moment I have a 40", 700 kg scrap-magnet dismantled here as a challenging repair job. It has the typical coaxial construction, a flat steel top plate 2" thick, a 12" diameter central pole with the other pole as a 2" thick annulus. The coil is inside, covered below by a non-magnetic plate, welded slightly inset, between the poles. Protection of the coil is very important. The non-magnetic plate used was often second hand manganese steel, light armour plate, about 1/2" thick.

Magnet coils can be wound for any voltage over about 50 volts, usually about 300V. Typically the DC supply will come from bridge-rectified three-phase 400V. That must be reduced, once the typically 50 amp current is flowing, to prevent overheating of the enclosed coil. The biggest challenge comes when turning off the current to kill the magnetic field quickly. The magnetic stored energy must be reliably dumped into a load. Failure of that load can result in a voltage spike that destroys the coil insulation.

A 4 foot diameter magnet will not start to pick up light pieces of steel until it is about 2 feet away. Any steel picked up that rests against the poles becomes a magnetic pole extension and so increases the range. The picture in berkeman's post above shows the way that chains of small scrap form between the poles. Those chains do not form until very close contact is made, typically 1".

The idea that a magnet can pick things up that are more than a "pole separation" away are fanciful.
Maybe you should explain what you are really trying to do.

 

[ChaserNZ]

At the moment I have a 40", 700 kg scrap-magnet dismantled here as a challenging repair job. It has the typical coaxial construction, a flat steel top plate 2" thick, a 12" diameter central pole with the other pole as a 2" thick annulus. The coil is inside, covered below by a non-magnetic plate, welded slightly inset, between the poles. Protection of the coil is very important. The non-magnetic plate used was often second hand manganese steel, light armour plate, about 1/2" thick.

Magnet coils can be wound for any voltage over about 50 volts, usually about 300V. Typically the DC supply will come from bridge-rectified three-phase 400V. That must be reduced, once the typically 50 amp current is flowing, to prevent overheating of the enclosed coil. The biggest challenge comes when turning off the current to kill the magnetic field quickly. The magnetic stored energy must be reliably dumped into a load. Failure of that load can result in a voltage spike that destroys the coil insulation.

A 4 foot diameter magnet will not start to pick up light pieces of steel until it is about 2 feet away. Any steel picked up that rests against the poles becomes a magnetic pole extension and so increases the range. The picture in berkeman's post above shows the way that chains of small scrap form between the poles. Those chains do not form until very close contact is made, typically 1".

The idea that a magnet can pick things up that are more than a "pole separation" away are fanciful.
Maybe you should explain what you are really trying to do.

I had a feeling this would become an issue, but for reasons of invention and patent I cannot yet disclose with much detail what I am attempting. Sorry, I don't mean to be an elusive pain in the ass but have little choice. Yet.

 

[ChaserNZ]

Oh, and thank you for your detail about your setup. Though I would have to modify greatly, there is some hope.

 

[Baluncore]

My advice to individuals who still believe in patents is that patents are a liability. You pay tens of thousands of dollars up-front to get a paper patent. A big corporation is then better off to challenge your patent than to license it from you. Their legal challenge will destroy you financially through legal costs and delays over the next decade. In the end you will not be able to pay the patent renewal fees and all is then lost. The probability that you have a novel idea that a corporation cannot argue around is very small. You must fight them all over the world. Good luck in China, and in the USA.

Get a prototype working if you can. Sell the IP if you can, or market the invention directly to local customers.

 

[davenn]

But what I lean toward is that scrap metal yards surely get past this issue, but how?

their electromagnets MUST come into contact with the metal they are picking up ... simple as that

 

[ChaserNZ]

Okay, so I have a somewhat new question, related though. Anyone here know about Bitter magnets? Apparently they can outperform other electromagnets a great deal, many tesla's beyond regular magnets, but use more power to do so? I read what Wikipedia had to say about the Bitter, but it left out many details. Like just how much energy required, ac or DC power, how much lift or pull x number of Tessa's gives in practical terms, and so on. Anyone know of some outfit that sells Bitter's and can I imagine give voltage and lift/attraction data?

 

[Baluncore]

The magnetic field of a Bitter magnet is concentrated on the inside of the structure.
Unfortunately, you need an external field.
The shape of a magnetic field is independent of it's strength.

 

[ChaserNZ]

Thanks, bummer I guess for my intended purpose. More digging to do...