Sujet : Re: bike light optics
De : frkrygow (at) *nospam* sbcglobal.net (Frank Krygowski)
Groupes : rec.bicycles.techDate : 10. Apr 2024, 22:21:04
Autres entêtes
Organisation : A noiseless patient Spider
Message-ID : <uv6sbi$1619k$1@dont-email.me>
References : 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
User-Agent : Mozilla Thunderbird
On 4/10/2024 2:39 PM, Jeff Liebermann wrote:
On Wed, 10 Apr 2024 12:36:37 -0400, Frank Krygowski
<frkrygow@sbcglobal.net> wrote:
On 4/10/2024 7:06 AM, Rolf Mantel wrote:
>
Cheap hub dynamoes have a rolling resistance in the order of 15W to
generate 3W. A good hub dynamo can probably get those 12W out of a
mechanical resistance in the order of 20W.
>
Wow. I wasn't aware that any hub dynamos were that inefficient. Can you
say which brands those are?
Ummm...
<https://www.google.com/search?q=%22cable+test%22+%22PWM%22>
Oops. That's related to cable PWM instead of hub dynamos.
You can see some typical
efficiencies and RPM/efficiency curves at:
<https://pedalcell.com/blogs/blog/maximizing-bicycle-charging-efficiency>
"A rider that tries to charge their phone with a common bicycle dynamo
system can lose over 60% of their power."
Which is still better than the "15W to generate 3W." That's why I asked.
BTW, most of the dynamos in that Efficiency bar graph are bottles or rollers, not hub dynamos. The hubs are at the top, between 45% and 60% efficient. Again, that's why I asked.
-- - Frank Krygowski
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