Is there an updated Dynotest somewhere?

On 9/10/2017 7:55 PM, James wrote:
On 10/09/17 15:24, bob prohaska wrote:
Sepp Ruf wrote:

As the more recent tests were mostly conducted "by SON's Andreas
Oehler or
one of his buddies," they have not met r.b.t's stringent anti-corruption
criteria:

https://www.cyclingabout.com/dynamo-hub-drag-lab-testing/
(is a translation of
https://fahrradzukunft.de/14/neue-nabendynamos-im-test/


That article actually comes somewhat close to what I was looking
for. The real disappointment is the photo: It shows a (very expensive)
Schmidt hub containing a clawpole armature.

That is somewhat borne out in the efficiency. It's only around 50%.
Seems to me Schmidt has considerable room for improvement. Even the
cheapest electric machines use laminated armatures.

If that represents the state of the hub dynamo art it's in a bad way.
They're obviously aware of eddy current losses (note the notch in
the visible pole piece) but the losses extend to the entire volume
of magnetic material. It's as if they're unaware of the skin effect.

For the moment I think I'll try to revive my old Soubitez roller dynamo
and hope somebody gets past the 19th century.


Notice the laminated magnetic material in the SP dynamo hub.

https://janheine.files.wordpress.com/2012/09/pv8.jpg

But it doesn't seem like it affected the efficiency very much. I think
we're chasing diminishing returns. The major point of the article at
https://www.cyclingabout.com/dynamo-...g-lab-testing/ is that the
drag is not much to worry about.

--
- Frank Krygowski