Neodymium Magnets: Does Size Matter?

AI Thread Summary
Neodymium magnets offer a stronger magnetic flux compared to standard magnets, but their use can introduce additional drag due to Lentz's law and cogging, potentially decreasing torque and RPMs if not properly managed. Increasing the air gap or power input may be necessary to maintain output levels when using stronger magnets. When replacing standard magnets with smaller neodymium magnets of equal strength, there can be a reduction in air resistance and weight, which may enhance efficiency. However, while input power might decrease, output will not increase if RPMs remain constant. Overall, the effectiveness of neodymium magnets depends on the specific application and design considerations.
Qaiphyx
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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.
 
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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.
 
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