bicyle dynamos etc...

Discussion in 'Cycling Equipment' started by Net, Apr 7, 2003.

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  1. Net

    Net Guest

    I'm interested to know what is the latest in dynamos/electric power generators for bicycles. I dont
    mean the subject of mains power replacement, I mean to power bicycle lights or recharge batteries
    while on the move. I've searched around a bit using google and viewed a few online cycle shops but
    can find little info on this. I've got a bicycle headlight that doubles as a battery charger for the
    4xAA's inside it but naturally it needs a 6v DC supply to do the re-charging. Has a dynamo been
    developed yet that supplies a constant 6V? I'm also surprised not to find a solar panel model
    anywhere. There are solar powered calculators so surely one could also use the same priciple to make
    a trickle charger. The possibilities are numerous. Even a small fan mounted mounted on the handlebar
    could drive a little dynamo that could trickle charge. I wish I was brainier with electronics...
     
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  2. net wrote:
    > I'm interested to know what is the latest in dynamos/electric power generators for bicycles. I
    > dont mean the subject of mains power replacement, I mean to power bicycle lights or recharge
    > batteries while on the move. I've searched around a bit using google and viewed a few online cycle
    > shops but can find little info on this. I've got a bicycle headlight that doubles as a battery
    > charger for the 4xAA's inside it but naturally it needs a 6v DC supply to do the re-charging. Has
    > a dynamo been developed yet that supplies a constant 6V? I'm also surprised not to find a solar
    > panel model anywhere. There are solar powered calculators so surely one could also use the same
    > priciple to make a trickle charger. The possibilities are numerous. Even a small fan mounted
    > mounted on the handlebar could drive a little dynamo that could trickle charge. I wish I was
    > brainier with electronics...

    The extra weight and resistance added make it far from worth it - thats why expensive bike lights
    have seperate, long life rechargable batteries that recharge OFF the bike.

    Solar panels wouldn't work too well, unless you plan on running those lights during the day, or
    leaving your bike with solar panels out sunning all day long and then power your LED light for a
    few hours ;)

    Jon Bond
     
  3. net wrote:
    >
    > I'm interested to know what is the latest in dynamos/electric power generators for bicycles. I
    > dont mean the subject of mains power replacement, I mean to power bicycle lights or recharge
    > batteries while on the move. I've searched around a bit using google and viewed a few online cycle
    > shops but can find little info on this.

    See http://www.myra-simon.com/bike/dynotest.html

    Also see http://www.sheldonbrown.com/dynohubs.html

    > I've got a bicycle headlight that doubles as a battery charger for the 4xAA's inside it but
    > naturally it needs a 6v DC supply to do the re-charging. Has a dynamo been developed yet that
    > supplies a constant 6V?

    As close as you need, yes. But understand, bike dyanamos are AC devices. You'd need recification, as
    mentioned in the second article above. That entails some losses in efficiency.

    > I'm also surprised not to find a solar panel model anywhere. There are solar powered calculators
    > so surely one could also use the same priciple to make a trickle charger.

    I was looking at solar yard lights the other day. A three-inch-square solar cell will charge two AA
    rechargeable batteries and run one dim LED for perhaps 8 hours. Based on that, I assume it will run
    two dim LEDs for about four hours, or four dim LEDs for two hours. Those dim LEDs won't light the
    road very well at all.

    What it comes down to is, solar isn't going to be worth the money. You could, of course, go with a
    more efficient solar panel (crystalline vs. amorphous), you could go with a bigger solar panel and
    bigger batteries, but to get enough solar electricity to run an adequate bike light (or anything
    else), solar will be too costly and cumbersome.

    Part of the problem is the energy losses involved in battery charging. I haven't been able to find
    the efficiency (and haven't troubled to measure it yet) but you definitely get less out of a battery
    than what you put in.

    > The possibilities are numerous. Even a small fan mounted mounted on the handlebar could drive a
    > little dynamo that could trickle charge.

    Keep in mind that YOU make the energy that spins the dynamo (unless your bike is parked in a breezy
    area). This is true whether it's driven by the relative wind you create, or by the spinning of your
    tire against a roller, or by the rotation of your hub directly driving the rotor in the dynamo.

    What matters, then, is how much energy is lost in the transfer. A propellor drive would be much less
    efficient than a roller on your tire, I think. The most efficient method is to have a direct drive
    mechanism without gears, like the Schmidt (or SON) dynamo mentioned in that first article.

    Also, to keep efficiency up, you'd NOT want to lose any power in storage. That means you generate
    the power as you need it, and feed it directly into a well-matched load. I don't think you're going
    to do better than the Schmidt.

    > I wish I was brainier with electronics...

    Study! ;-)

    --
    Frank Krygowski [email protected]
     
  4. Jeff Wills

    Jeff Wills Guest

    net <[email protected]> wrote in message news:<[email protected]>...
    > I'm interested to know what is the latest in dynamos/electric power generators for bicycles. I
    > dont mean the subject of mains power replacement, I mean to power bicycle lights or recharge
    > batteries while on the move.
    <snip>
    > I wish I was brainier with electronics...

    A good place to ask these questions is the bikecurrent list:
    http://www.topica.com/lists/bikecurrent/read

    These people are brainy.

    Jeff
     
  5. Frank Krygowski <[email protected]> writes:

    > net wrote:
    >>
    >> I'm interested to know what is the latest in dynamos/electric power generators for bicycles. I
    >> dont mean the subject of mains power replacement, I mean to power bicycle lights or recharge
    >> batteries while on the move. I've searched around a bit using google and viewed a few online
    >> cycle shops but can find little info on this.
    >
    > See http://www.myra-simon.com/bike/dynotest.html

    That's interesting. Unfortunately, what seems to be a very good new dynamo is not included in this
    test: the LightSpin.

    According to VeloPlus' current data, the LightSpin is the most efficient dynamo on the market today,
    even better than Schmidt's dynamo hub, as can be seen in their test results (in german, but the
    table is easily understood):

    http://www.veloplus.ch/info/info-beleuchtung.html

    There was an article in the first issue of VeloVision (http://www.velovision.co.uk/) about the
    LightSpin, which is available as a PDF file there (in english):

    http://www.eland.uklinux.net/mag/issue1lightspin.pdf

    Finally, the maker of the dynamo has a web site which includes some information about its product:

    http://www.dynosys-ag.ch/

    (Disclaimer: I have no relationship with them, I'm not even a customer, but I read several good
    reviews of this dynamo).

    Michel.
     
  6. M Gagnon

    M Gagnon Guest

    "Michel Schinz" <[email protected]> a écrit dans le message de news:
    [email protected]
    > Frank Krygowski <[email protected]> writes:
    >
    > > net wrote:
    > >>
    > >> I'm interested to know what is the latest in dynamos/electric power generators for bicycles. I
    > >> dont mean the subject of mains power replacement, I mean to power bicycle lights or recharge
    > >> batteries while on the move. I've searched around a bit using google and viewed a few online
    > >> cycle shops but can find little info on this.
    > >
    > > See http://www.myra-simon.com/bike/dynotest.html
    >
    > That's interesting. Unfortunately, what seems to be a very good new dynamo is not included in this
    > test: the LightSpin.

    If I remember correctly, the article is a few years old, and compares, amongst other things, an old
    version of the Shimano Nexus Dynohub. There is some data available on Peter White Cycle's website.
    See http://www.peterwhitecycles.com and check for products/lights. Peter White sells the SON -- an
    expensive but great no-friction hub (well, almost) -- and the Shimano Nexus, which is also very
    good, although a bit notchy _when_ the light is turned on, but not when the light is turned off. If
    I compare both, I would say that if you plan to cyle mostly in daytime, the Shimano is a very good
    altermative, as it is much cheaper and probably doesn't add too much resistance (in real life: add 5
    psi to your tires and you'll break even). On Peter White's site, the technical page on dynamo lights
    is a good factual one, which should be read. Apart from the graphics (lifted from SON's website),
    all the text is in English.

    Alas, the LIghtSpin is not covered. However, I tried to buy one for a few months and it was always
    back-order, and I heard of a few reliability problems (on iBOB and Bike Current lists). IOW: buyer
    beware, but I would be more cautious, especially if you don't buy locally.

    In terms of recharging, there have been a few homebrew projects like that, but it adds weight,
    reliability problems, cost... for not too much gain. I would see an advantage for off-road riding,
    but then battery-operated lights are likely to be a better and cheaper alternative for such
    situations. For on-road riding, the SON and Shimano Nexus with a good headlight (the Lumotec I have
    or the BiSi) offer plenty of lighting, except maybe when riding over 20 km/h. Then, a dual-headlight
    system as explained on Peter White's site solves the problem. The only real limitation of a
    generator-based light is that it shuts down when you stop. It is possible to buy a headlight and a
    taillight with a standlight feature that allows 3-5 minutes sitting. Alternatively, it's possible to
    use a battery taillight (good autonomy with LEDs) and a generator-based headlight.

    BTW, if you want to practice at building wheels, then a lighting system based on a Shimano Nexus
    cost about $110-120.

    Regards,

    Michel Gagnon
     
  7. On Tue, 08 Apr 2003 01:49:51 -0400, Michel Schinz wrote:

    > According to VeloPlus' current data, the LightSpin is the most efficient dynamo on the market
    > today, even better than Schmidt's dynamo hub, as can be seen in their test results (in german, but
    > the table is easily understood):

    However that calculation omits losses in driving the generator with the tire. There are no such
    losses with the Schmidt.
     
  8. Peter

    Peter Guest

    Steve Palincsar wrote:
    > On Tue, 08 Apr 2003 01:49:51 -0400, Michel Schinz wrote:
    >
    >
    >>According to VeloPlus' current data, the LightSpin is the most efficient dynamo on the market
    >>today, even better than Schmidt's dynamo hub, as can be seen in their test results (in german, but
    >>the table is easily understood):
    >
    >
    >
    > However that calculation omits losses in driving the generator with the tire. There are no such
    > losses with the Schmidt.

    ?? I didn't see any calculations at the referenced website - just some test results reportedly from
    the computerized facilities of the Schmidt company in Tubingen. They didn't give any details of the
    test setup, but I'd think the most straight-forward way to test dynamos would be to mount them on a
    bike frame and see how much input power is required to spin the bike tire and compare to the amount
    of electrical produced. There was a footnote on the test for one of the Union models that the medium
    level of applied force was chosen for the test, which suggests that the test did involve driving the
    dynamo with a bike tire.

    On what basis do you conclude that energy losses associated with the bicycle tire were not included?

    BTW, does the LightSpin dynamo actually exist as a consumer product (as opposed to prototypes)? If
    so are there any dealers who carry it in the US?
     
  9. A Muzi

    A Muzi Guest

    > > > net wrote:
    > > >> I'm interested to know what is the latest in dynamos/electric power generators for bicycles.
    > > >> I dont mean the subject of mains power replacement, I mean to power bicycle lights or
    > > >> recharge batteries
    while
    > > >> on the move. I've searched around a bit using google and viewed a few online cycle shops but
    > > >> can find little info on this.

    > > Frank Krygowski <[email protected]> writes:
    > > > See http://www.myra-simon.com/bike/dynotest.html

    > "Michel Schinz" <[email protected]> a écrit dans le message de news:
    > [email protected]
    > > That's interesting. Unfortunately, what seems to be a very good new dynamo is not included in
    > > this test: the LightSpin.

    "M Gagnon" <[email protected]> wrote in message news:[email protected]...
    > If I remember correctly, the article is a few years old, and compares, amongst other things, an
    > old version of the Shimano Nexus Dynohub. There
    is
    > some data available on Peter White Cycle's website. See http://www.peterwhitecycles.com and check
    > for products/lights. Peter White sells the SON -- an expensive but great no-friction hub (well,
    > almost) -- and the Shimano Nexus, which is also very good, although a bit notchy _when_ the light
    > is turned on, but not when the light is turned
    off.
    > If I compare both, I would say that if you plan to cyle mostly in daytime, the Shimano is a very
    > good altermative, as it is much cheaper and probably doesn't add too much resistance (in real
    > life: add 5 psi to your tires and you'll break even). On Peter White's site, the technical page on
    > dynamo lights is a good
    factual
    > one, which should be read. Apart from the graphics (lifted from SON's website), all the text is in
    > English.
    >
    > Alas, the LIghtSpin is not covered. However, I tried to buy one for a few months and it was always
    > back-order, and I heard of a few reliability problems (on iBOB and Bike Current lists). IOW: buyer
    > beware, but I would
    be
    > more cautious, especially if you don't buy locally.
    >
    > In terms of recharging, there have been a few homebrew projects like that, but it adds weight,
    > reliability problems, cost... for not too much gain. I would see an advantage for off-road riding,
    > but then battery-operated
    lights
    > are likely to be a better and cheaper alternative for such situations. For on-road riding, the SON
    > and Shimano Nexus with a good headlight (the
    Lumotec
    > I have or the BiSi) offer plenty of lighting, except maybe when riding
    over
    > 20 km/h. Then, a dual-headlight system as explained on Peter White's site solves the problem. The
    > only real limitation of a generator-based light is that it shuts down when you stop. It is
    > possible to buy a headlight and a taillight with a standlight feature that allows 3-5 minutes
    > sitting. Alternatively, it's possible to use a battery taillight (good autonomy
    with
    > LEDs) and a generator-based headlight.
    >
    > BTW, if you want to practice at building wheels, then a lighting system based on a Shimano Nexus
    > cost about $110-120.

    Lite Spin Hard to find? We have 'em. These things are amazing compared to other bottle dynamos. When
    you spin the thing in your fingertips the pulley stays spinning for several seconds. And of course
    when it's off the tire there is zero drag. http://www.yellowjersey.org/litespin.html

    --
    Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971
     
  10. M Gagnon <[email protected]> wrote: [Shimano vs. SON.]
    >If I compare both, I would say that if you plan to cyle mostly in daytime, the Shimano is a very
    >good altermative,

    I think this is backwards, to be frank. The Shimano's performance is much the same when operating as
    the SON; but the Shimano's drag is greater when switched off than the SON; hence if you cycle mostly
    in daylight the SON is preferable. In the extreme case where you have such peculiar working hours
    that you only ever cycle in the dark, the Shimano would be just as good as the SON.

    >are likely to be a better and cheaper alternative for such situations. For on-road riding, the SON
    >and Shimano Nexus with a good headlight (the Lumotec I have or the BiSi) offer plenty of lighting,
    >except maybe when riding over 20 km/h.

    I think this speed is overly conservative; I have no difficulty at speeds of 40 km/h, which is about
    my peak speed on a journey I make regularly sections of which are completely unlit.
    --
    David Damerell <[email protected]> flcl?
     
  11. Tue, 8 Apr 2003 12:36:02 -0400, M Gagnon:

    >If I remember correctly, the article is a few years old,

    It is from 1997 - a lot of the newer dynamos were not available then.

    >and compares, amongst other things, an old version of the Shimano Nexus Dynohub.

    A fairly actual test was done by german magazin "aktiv Radfahren". It covers the new models by
    Shimano, the new model by Schmidt and also the Lightspin.

    See a rough translation at: http://groups.google.com/groups?q=%22oehler%22++test+shimano+quattro&hl-
    =de&lr=&ie=UTF-8&selm=7v9j3d%24oe5%241%40pegasus.csx.cam.ac.uk&rnum=1

    But keep in mind that a laboratory test did not represent the conditions on the road - like the
    slipping Lightspin in the wet or the problems of some sidewall dynamos which are heavily shaken on
    suspension forks...

    Andreas
     
  12. Steve Palincsar wrote:
    >
    > On Tue, 08 Apr 2003 01:49:51 -0400, Michel Schinz wrote:
    >
    > > According to VeloPlus' current data, the LightSpin is the most efficient dynamo on the market
    > > today, even better than Schmidt's dynamo hub, as can be seen in their test results (in german,
    > > but the table is easily understood):
    >
    >
    > However that calculation omits losses in driving the generator with the tire. There are no such
    > losses with the Schmidt.

    If I recall correctly, the test setup does measure contact driving losses. It's a flywheel with a
    bike wheel & tire (or equivalent) and it records the deceleration of the flywheel to determine
    generator drag. Anything that would be felt by the rider would also be felt by the flywheel system.

    --
    Frank Krygowski [email protected]
     
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