Neodymium Magnets: Does Size Matter?

Click For Summary

Discussion Overview

The discussion revolves around the impact of using neodymium magnets compared to traditional magnets in applications such as alternators. Participants explore the implications of magnet size, strength, and efficiency in relation to energy output, focusing on theoretical and practical aspects of magnet performance.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants suggest that neodymium magnets, being stronger, create a stronger magnetic flux but may also introduce additional drag due to Lentz's law and cogging effects.
  • It is proposed that increasing the air gap may be necessary to maintain performance when using stronger magnets, or alternatively, increasing power to avoid decreased torque and RPMs.
  • One participant notes that using a smaller neodymium magnet with the same strength as a traditional magnet could lead to less air resistance, potentially increasing efficiency.
  • Another viewpoint indicates that while neodymium magnets could reduce weight and air resistance, the output may not increase if the RPMs remain the same, although input might decrease.
  • A different participant mentions that traditional alternators typically use field coils rather than permanent magnets, suggesting a different operational mechanism that may not directly relate to the discussion on neodymium magnets.

Areas of Agreement / Disagreement

Participants express varying opinions on the effects of neodymium magnets, with some agreeing on the potential for increased efficiency while others highlight the complexities and trade-offs involved. The discussion remains unresolved regarding the overall impact on energy output when substituting different types of magnets.

Contextual Notes

Participants acknowledge that the effectiveness of neodymium magnets may depend on specific design considerations and operational parameters, such as air gaps and RPMs, which are not fully explored in the discussion.

Qaiphyx
Messages
92
Reaction score
0
They pull a lot of pounds in ratio to their size, I was wondering if it would make any difference in the energy output if you replaced the normal magnet with a neodyniam.
 
Engineering news on Phys.org
It depends...

A stronger magnet will of course create a stronger flux, but it will create additional drag due to Lentz law and "cogging". As such - the air gap will have to be increased to keep things "equal", or power increased - else the torque and RPM's will decrease, resulting in lower output.
If building from scratch - I would use neos. Reworking an existing unit will probably not be benificial as it would (should) have been designed to work best with the current flux.

CH
 
capthook said:
It depends...

A stronger magnet will of course create a stronger flux, but it will create additional drag due to Lentz law and "cogging". As such - the air gap will have to be increased to keep things "equal", or power increased - else the torque and RPM's will decrease, resulting in lower output.
If building from scratch - I would use neos. Reworking an existing unit will probably not be benificial as it would (should) have been designed to work best with the current flux.

CH

So then if you have a smaller neo at same strength as a normal magnet if would have less air resistance, slightly increasing efficiency right?
 
Qaiphyx said:
They pull a lot of pounds in ratio to their size, I was wondering if it would make any difference in the energy output

If you replace them with neos of equal gauss rating, rather than size - the magnets would be smaller. So yes - less air resistance, as well as weight, could result in an increase in efficiency. The output wouldn't increase if running at the same RPMs as before - but the input might decrease.
 
Qaiphyx said:
They pull a lot of pounds in ratio to their size, I was wondering if it would make any difference in the energy output if you replaced the normal magnet with a neodyniam.

I googled "how does an alternator work". They doen't seem to use permanent magnets, but field coils. By controlling how much current flows through the field coils the output voltage of the alternator can be regulated.
 
Last edited:

Similar threads

AC and Electrolysis
  • · Replies 11 ·
Replies
11
Views
1K
Assistance with practical electromagnetism project
  • · Replies 2 ·
Replies
2
Views
3K
Need an electromagnet to play Chess
  • · Replies 37 ·
2
Replies
37
Views
5K
Undergrad How to calculate the kinetic energy of an object propelled by a magnet?
  • · Replies 15 ·
Replies
15
Views
1K
Is neodymium powder as strong of a magnet as solid neodymium
  • · Replies 7 ·
Replies
7
Views
4K
Electromagnet not repelling neodymium magnet
  • · Replies 4 ·
Replies
4
Views
4K
Strong motor using permanent magnets?
  • · Replies 9 ·
Replies
9
Views
3K
Help in trying to build microcontroller powered Chess Board
  • · Replies 1 ·
Replies
1
Views
2K
What size does electromagnet has to be to imitate the power of neodymium magnet?
  • · Replies 1 ·
Replies
1
Views
3K
Undergrad Permeability of Metglas and Propagation Velocity
  • · Replies 5 ·
Replies
5
Views
2K