10 footer coil mods

[hapuna beach]

Hi all. This is my first post. I'm looking to build one of the 10 foot machines featured here, but had a question regarding coil turns v/s magnet strength. From what I've gathered, if using the N35 magnets, the following applies:

• For 12 Volt machines you need to wind with two strands of #14 gage wire in hand and each coil should have 36 turns.
  
• For 24 Volt machines wind with 1 strand of #14 gage wire and each coil should have 70 turns.
  
• For 48 Volt machines wind with 1 strand of #17 gage wire and each coil should have 140 turns.
  
  

My question is, if everything else stays the same, how many turns would be required if I used N40 magnets for each of the above?

Thanks,

Hapuna

[SparWeb]

I'll take a first poke at this one: my guess is don't change anything.  Your magnets push more lines of flux through the coils and there will be several effects.  The cut-in speed will be a tad lower, and the current will be a tad higher for a given RPM.  Use the same prop and you'll see virtually identical performance.

That is, of course, assuming everything else is identical.  The designer is the final authority, so let Dan confirm or deny my suspicion.

[Flux]

I tend to agree, in theory you can reduce the number of turns by about 5% but it will be easier to keep things the same and increase the air gap to give you a safer working clearance.

I don't think a little extra flux will hurt that design. Going up to N50 you may be advised to reduce turns a bit especially for the 24 & 48v case.

Much will depend on the line resistance to the alternator. With high voltage and short lines then you would likely have to open the gap less if you reduce turns a bit. With 12v and long lines you may find the extra flux an advantage with the same air gap.

Everything is a compromise, the winding that suits one wind area may not be best for another.

DanB will no doubt have a better idea of how near stall this winding is and how it will react to a small increase in flux.

Flux

[DanB]

I would leave the windings the same.  I think this setup runs a touch on the fast side anyhow, with a 10' blade.  I've used slighly larger magnets with the same stator with good results so going up a touch in grade certainly can't hurt.

[BruceDownunder]

I'd hold off a little while on the Neo conversion . Mine is not behaving like I expected ,although I have overcome the cogging , there seems something amiss in the power producing dept, -either the Neo conversion or the re-configuring of the stator -Don't know ..

Bruce

[BruceDownunder]

Sorry, my post was mean't for the F&P posting ,,but since then ,an hour ago, I've discovered my fault --magnets in the wrong way --so ,hopefully ,all will be OK soon.

Bruce

[hapuna beach]

Hi Dan,

I assume by your statement "runs a touch on the fast side" means the cut-in speed as such is high, but with the slightly stronger magnets, it begins producing usable power at a slower speed?

Thanks,

Hapuna