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dynamo rebuilding



 
 
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  #1  
Old April 1st 16, 11:20 AM posted to rec.bicycles.tech
Yin goo
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Posts: 9
Default dynamo rebuilding

I have a couple old but functional dynamo - One bottle, one roller. I'm
wondering if the electrical efficiency/efficacy can be improved by
rebuilding the dynamos. Has anyone have any experience with this? I
understand that i could potentially rewind the coils, replace the bearing
but how practical is this ... Before i attempt it on an otherwise
functional device. What else is practical to change; the magnet? More
poles? Any other interesting hacks or improvements?

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  #2  
Old April 1st 16, 04:10 PM posted to rec.bicycles.tech
Tim McNamara
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Posts: 6,945
Default dynamo rebuilding

On Fri, 1 Apr 2016 10:20:16 -0000 (UTC), Yin goo
wrote:
I have a couple old but functional dynamo - One bottle, one roller.
I'm wondering if the electrical efficiency/efficacy can be improved by
rebuilding the dynamos. Has anyone have any experience with this? I
understand that i could potentially rewind the coils, replace the
bearing but how practical is this ... Before i attempt it on an
otherwise functional device. What else is practical to change; the
magnet? More poles? Any other interesting hacks or improvements?


I suspect not other than making sure the bearings are lubricated. Well,
I guess that would depend on how much you understand electrical
engineering and what tools you have.

I have a Sanyo roller and Andrew sent me instructions on how to tear
down and rebuild it. Probably has to be done ever 10 years or so.

The modern hub dynamos are very very good- Schmidt, Shimano, Shutter,
etc. The new generation of LED head- and taillights are likewise very
good. While I found my halogen headlights perfectly fine for all-night
rides in the country, the LEDs are usefully brighter and the optics are
improved to focus the light on the road and not in driver's eyes. If
you really want to improve the utility of your existing dynamos, just
upgrade the lights. My Schmidt eDelux is excellent and there are some
more refined lights that have come out since.
  #3  
Old April 1st 16, 09:35 PM posted to rec.bicycles.tech
ian field
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Posts: 1,008
Default dynamo rebuilding



"Yin goo" wrote in message
...
I have a couple old but functional dynamo - One bottle, one roller. I'm
wondering if the electrical efficiency/efficacy can be improved by
rebuilding the dynamos. Has anyone have any experience with this? I
understand that i could potentially rewind the coils, replace the bearing
but how practical is this ... Before i attempt it on an otherwise
functional device. What else is practical to change; the magnet? More
poles? Any other interesting hacks or improvements?


The old Sturmey Archer hub dynamos had very low remenance magnets that lost
their power instantly if you removed the coil assembly from them. Other
dynamos of the same era probably used similar materials for the magnet.

There's a blog floating about the web somewhere - someone built their own SA
magnet ring by bonding neodymium magnets to a steel hoop, they claimed a
significant increase in output.

  #4  
Old April 2nd 16, 02:41 AM posted to rec.bicycles.tech
John B.[_6_]
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Posts: 2,202
Default dynamo rebuilding

On Fri, 1 Apr 2016 10:20:16 -0000 (UTC), Yin goo
wrote:

I have a couple old but functional dynamo - One bottle, one roller. I'm
wondering if the electrical efficiency/efficacy can be improved by
rebuilding the dynamos. Has anyone have any experience with this? I
understand that i could potentially rewind the coils, replace the bearing
but how practical is this ... Before i attempt it on an otherwise
functional device. What else is practical to change; the magnet? More
poles? Any other interesting hacks or improvements?


The output of a generator is dependent on the speed of rotation and
the number of poles and the strength of the magnetic field. It will
probably be very difficult, or impossible, to change the number of
poles but it might be possible to increase the strength of the
magnets.
--
cheers,

John B.

 




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