How is this magnet too strong?

  • Thread starter DHS Science
  • Start date
  • Tags
    Magnet
In summary, a person was using a 12 volt car battery and a 6 gauge wire wrapped around an iron rod to make an electromagnet. However, the wire would only last around 30 seconds before melting completely. It was pointed out that using a heavy load on a car battery can be dangerous and could cause the battery to explode. It was suggested to use a high-current lab power supply instead and to be careful when dealing with high powers. It was also mentioned that the amount of power used in this situation was more than enough to burn things and personal experiences were shared where similar situations resulted in dangerous outcomes. It was advised to seek professional help when dealing with such things.
  • #1
DHS Science
16
0
I have a 12 volt car battery hooked up directly to a 6 gauge wire that is wrapped around an iron rod. For some reason the wire can only last around 30 seconds and the wire completely melts and no longer works.

How is it that a 12 volt battery has enough amps to melt a 6 gauge wire?
 
Engineering news on Phys.org
  • #2
Lordy, please be careful doing stuff like that, especially if you don't understand why the wire is melting. When you put such a heavy load on a car battery like that, you could cause all kinds of problems with the battery, including having it explode on you. Acid everywhere, maybe some fire -- you know, dangerous stuff.

Please consider using a high-current lab power supply instead of a car battery. At least with that, you can eliminate the explosion, acid and fire aspects. Then you are just left with looking in wire tables for the maximum rated current for the particular wire you are using. Use the resistivity numbers for the wire (in Ohms per kilometer or whatever) to calculate the resistance of some length of the wire, and from that you can figure out how many turns of wire to use to match the output impedance of the voltage source. Please be careful when dealing with these kind of powers!
 
  • #3
If you want to make an electromagnet you should be using many turns of small gauge enamel-insulated magnet wire. There are lots of resources on the web and in college libraries on how to do this and what the tradeoffs are. There is no substitute in engineering and physics for gaining knowledge, and you need some!
 
  • #4
What you did was very dangerous!
 
  • #5
The battery won't last long after such extreme current consumption. You pulled easily more than 100 amps in 30 seconds.

Power = I^2 * R, assuming the resistance of the wire is low let's say 0.5 Ohms, power used then = 5000 WATTS or Joules/S

In 30 seconds you unloaded 5000 W * 30 S = 150,000 JOULES of energy.

That is more than ample to burn a lot of things.


A fully charged car battery can hold 4.3 Mega Joules

http://home.earthlink.net/~jimlux/energies.htm

Interesting.
 
  • #6
An example of the potential hazard from personal experience:
When I first kicked the compression ratio of my 440 up to 12.5:1, the stock 350 amp battery wouldn't even turn it over. I had to put a 690 amp tractor battery in the trunk and wire it in parallel with the stock one (using 2# welding cable). Upon the first starting attempt, it fused the field windings in the starter.
I had to have a 5hp one custom-made with an extra 25 turns to handle it. :grumpy:
On another occasion (with a 'normal' battery), a friend accidentally shorted the terminals with a 3/8" open-end wrench. It melted almost completely through before he could knock it loose, and you wouldn't believe the fireworks!
 
  • #7
Danger said:
An example of the potential hazard from personal experience:
When I first kicked the compression ratio of my 440 up to 12.5:1, the stock 350 amp battery wouldn't even turn it over. I had to put a 690 amp tractor battery in the trunk and wire it in parallel with the stock one (using 2# welding cable). Upon the first starting attempt, it fused the field windings in the starter.
I had to have a 5hp one custom-made with an extra 25 turns to handle it. :grumpy:
On another occasion (with a 'normal' battery), a friend accidentally shorted the terminals with a 3/8" open-end wrench. It melted almost completely through before he could knock it loose, and you wouldn't believe the fireworks!

I don't think any newbies wonder why his hanbdle is DANGER! :biggrin: :biggrin:
 
  • #8
Wow man, u did some dangerous stuff(not to sound like an angry mother) that could have potentially hurt you. you should get professional help on this from a professor or someone good with that sort of thing. i may not know a lot about this stuff but one things for sure...

when wire starts melting, god knows their's too much power
 

1. What causes a magnet to be too strong?

The strength of a magnet is determined by its magnetic field, which is produced by the alignment of its microscopic magnetic domains. If these domains are closely packed and aligned, the magnet will have a stronger magnetic field, making it appear too strong.

2. Can a magnet be too strong for its intended purpose?

Yes, a magnet can be too strong for its intended purpose. For example, if a magnet is used to hold lightweight objects, but its magnetic field is too strong, it may cause damage or difficulty in removing the object.

3. How can I tell if a magnet is too strong?

One way to determine if a magnet is too strong is by using a gaussmeter, which measures the strength of a magnetic field. If the reading is significantly higher than the expected strength for the type of magnet, it may be considered too strong.

4. Is it possible to weaken a strong magnet?

Yes, it is possible to weaken a strong magnet by demagnetizing it. This can be done by exposing the magnet to high temperatures, hammering it, or using an alternating magnetic field. However, these methods may also damage the magnet.

5. Can a strong magnet be dangerous?

Yes, a strong magnet can be dangerous if proper precautions are not taken. The strong magnetic field can affect electronic devices, cause metal objects to fly towards it, or even cause injury if handled improperly. It is important to handle strong magnets with caution and store them away from sensitive materials.

Similar threads

Replies
4
Views
664
  • Electrical Engineering
2
Replies
58
Views
2K
Replies
76
Views
7K
  • Electrical Engineering
Replies
3
Views
1K
Replies
7
Views
2K
  • Electrical Engineering
Replies
10
Views
2K
  • Electrical Engineering
Replies
22
Views
3K
  • Electrical Engineering
Replies
6
Views
3K
  • Introductory Physics Homework Help
Replies
14
Views
963
  • Electrical Engineering
Replies
11
Views
4K
Back
Top