Published a blog post about my experience with dynamos and dynamo lighting if you're interested. Posted about a week ago, I figured I'd link it here for the archives. It's about as boiled down as I could make it but it's a big topic, and still kinda long.
That is all.
_________________ GREAT UNITER / ORACLE / ELDER
MOOAAR DONGS
Bo Ttorff
Posted: Tue Jun 12, 2012 4:26 pm
GO SEAHAWKS!! 12 for LYFEJoined: 20 Jul 2011Posts: 3092Location: King County
that was informative for me, muchos gracias's
caustic meatloaf
Posted: Tue Jun 12, 2012 4:34 pm
Joined: 06 Dec 2010Posts: 1235537Location: a hammy melange...
The STVZO spec is very much German. Better than spec = NOT APPROVED. Speaking of which, does anyone offer a decently priced dynamo system that has the ability to put out greater than 3W, or offer voltages other than 6V?
And is that Philipps the one I ate? And as an explanation for the artifacts you saw using it in the farfield, look at the mirror orientation inside - those ridges will cause uneven illumination in the longer distance, likely causing those tiger stripes.
_________________ HIS NAME IS EDMUND
tehschkott
Posted: Tue Jun 12, 2012 5:05 pm
daywalkerJoined: 09 Nov 2007Posts: 6108Location: Hatertown
caustic meatloaf wrote:
And is that Philips the one I ate? And as an explanation for the artifacts you saw using it in the farfield, look at the mirror orientation inside - those ridges will cause uneven illumination in the longer distance, likely causing those tiger stripes.
The one you ate? I don't know what you mean.
I know what the artifacts are from, it doesn't make them less distracting or that light less of a piece of shit for a dozen other reasons.
caustic meatloaf wrote:
The STVZO spec is very much German. Better than spec = NOT APPROVED. Speaking of which, does anyone offer a decently priced dynamo system that has the ability to put out greater than 3W, or offer voltages other than 6V?
If I understand correctly the short answer is: no.
3W dynamos complying with the STVZO are designed to saturate at 15 kph under a specific resistance load. STVZO hubs stop producing more than 3W of power once they hit 15kph. (or 2.4W dynamos if talking about 2.4W dynamos).
The long answer of course is more complicated and filled with caveats. If you want to fuck around with resistance loads it is possible to get more than 3W out of a hub, but as I understand it that accompanies a corresponding increase in drag too. I don't think you're going to get 5~7W without paying for it, and the effort/gain ratio starts falling off pretty fast after crossing the red line.
But don't take my word on it. I recently asked Wouter that very question - he replied today.
The STVZO spec is very much German. Better than spec = NOT APPROVED. Speaking of which, does anyone offer a decently priced dynamo system that has the ability to put out greater than 3W, or offer voltages other than 6V?
Both Shimano and Schmidt dynohubs put out over 6V and 3W at normal riding speeds. The headlights regulate them down. There are many homemade headlights that have gotten 7 or 8 watts out of these hubs. The E3 headlights are commercial ones that probably do.
The resistance is more noticeable if you use more power, to me that is a downside. I haven't really found a place yet where the IQ Cyo wasn't bright enough, and I think it is consuming under 2 watts.
tehschkott
Posted: Tue Jun 12, 2012 10:12 pm
daywalkerJoined: 09 Nov 2007Posts: 6108Location: Hatertown
See - that's what I thought! But I had a couple reputable sources tell me otherwise - I argued it had to be at the lamp and they maintained it was at the dynamo and the lamp.
Learning.
_________________ GREAT UNITER / ORACLE / ELDER
MOOAAR DONGS
saccade
Posted: Wed Jun 13, 2012 3:35 pm
Joined: 19 May 2009Posts: 323Location: monkey lab
Well the thing is "how much volts/watts/amps" a hub puts out is a function of both the hub and the load. I think you extract the most power when the impedance of the load matches the hub. But the higher the operating frequency the more the inductance of the hub determines its impedance. So a hub driving a purely resistive load tends to taper off in power production at high speeds.
You can use capacitors to match impedance, but again, how much capacitance you need depends on your speed and the input load. It's a complicated problem with a bicycle dynamo that can go at all different speeds.
Someone with better EE background might make more sense here.
TBH I can't even notice the difference between lights off and on. I'd like to get a bit more power output so that e.g. a cell phone charger actually charges with the lights on.
Joined: 06 Dec 2010Posts: 1235537Location: a hammy melange...
I'm also a bit rusty on my EE knowledge, but I always enjoyed power electronics, so this is slightly less rusty.
In short, Scott's right - you can definitely design a dynamo to saturate at a given frequency. At that point, your linear power output levels off significantly, and you get very little power increase when you increase the frequency.
So, that's power limitation factor #1.
#2 lies in the rectification circuits. Because they need to cover a wide range of input frequencies, you're likely going to have a variable duty cycle switched rectification circuit, and that's probably feeding to some sort of buck/boost converter. Just through the design of the components, the manufacturer likely will also limit power output (probably constant voltage, and current limited to 500mA).
you could probably check on this with a couple VOMS on the power leads of the dynamo - hook one up directly to the leads to monitor voltage, and then take a variable resistor (5Kohm to 0ohm), and connect the other multimeter in series to measure current. As you lower the resistance, you should see current increase, and then plateau - or you'll see the voltage continue to drop while current increases. Wherever the voltage starts dropping quickly, that's the cutoff current that the dynamo is designed for.
You could try that at different rotational speeds to see how consistent the power output is as well.
Impedance matching is something to design for on loads for AC circuits, but in this case, dynamos put out DC current to the load, so it's not really relevant here. And impedance matching for AC circuits is really only a factor to consider at high frequencies or VERY long distances.
_________________ HIS NAME IS EDMUND
saccade
Posted: Wed Jun 13, 2012 4:49 pm
Joined: 19 May 2009Posts: 323Location: monkey lab
Bike dynamos put out AC with the rectification/regulation in the lamp, though I'm not sure that's relevant to what you're saying.
What's the mechanism for saturation? Ferromagnetic stuff? I wonder how that PV-8 dynamo behaves as it's supposed to not use iron cores.
Joined: 06 Dec 2010Posts: 1235537Location: a hammy melange...
I'm thinking of the power being supplied to the light as being the load - so even if the rectification circuit is in the light, the power's still gotta go through that to get to the light.
You know, I'd be curious to see what the AC waveform looks like - depending on design, if they have a multi-pole dynamo, rectification could be done relatively easily.
With a very broad brush, saturation is the point where the magnetic field induced on the armature by a stator element can't attenuate fast enough before it runs into another stator element, so you end up with a non-linear induced magnetic field, which will create a non-linear voltage output.
_________________ HIS NAME IS EDMUND
rob
Posted: Wed Jun 13, 2012 6:31 pm
Joined: 28 Jul 2007Posts: 1315Location: Columbia City
Goddamn nerds.
blasdelf
Posted: Thu Jun 14, 2012 3:21 pm
BAD NAVIGATORJoined: 01 Mar 2010Posts: 1505
caustic meatloaf wrote:
You know, I'd be curious to see what the AC waveform looks like - depending on design, if they have a multi-pole dynamo, rectification could be done relatively easily.
You can feel the multitude of poles turning the shaft in your hand (TWSS, I know)
There's around 25 on average, more in some hubs and less in what Scott's calling '2.4w' hubs (really their power curve is just shifted up to slightly higher RPMs, they were originally only kraut-legal in 20" wheels because of that)
caustic meatloaf
Posted: Thu Jun 14, 2012 4:36 pm
Joined: 06 Dec 2010Posts: 1235537Location: a hammy melange...
Hell, with a 24 pole dynamo, 1)saturation can happen pretty quickly, and 2)Why even rectify? The ripple is going to be not a lot, probably more than within tolerance for some LEDs.
_________________ HIS NAME IS EDMUND
saccade
Posted: Thu Jun 14, 2012 5:39 pm
Joined: 19 May 2009Posts: 323Location: monkey lab
It's got a lot of poles because wheels turn very low RPM. 24 poles at 15 mph on a 700x32 wheel works out to 37 Hz power.
The simplest ghetto lighting is to have two LEDs wired up antiparallel so that each one takes half the cycle and protects the other from breaking down in reverse bias. I've set up something like that before with one light in a tight forward beam and another in a low horizontal beam. It works, but below 10mph it's annoyingly stroboscopic.
You don't need to rectify a simple LED (just give it a diode for the other direction) if you don't care about a standlight. Most headlights are using a bridge rectifier though. The good electronics get complex enough that I stopped bothering to try and make my own (the best that I could do for a standlight circuit that acted like the IQ Cyo was a mix of through hole and surface mount parts on a board 1" diameter and 3/8" tall). The design is fairly simple, compact and lightweight implementation is complex.
I'm pretty sure that the waveform is a very clean sine wave, I can't even really see a way for it to be anything else given the super simple design of these things.
I do find the vibration in the handlebars annoying when riding a dynohub bike that has a high load. I'm glad that we've moved beyond the days of dual Lumotec (halogen) headlights attached to a SON28.
tehschkott
Posted: Mon Jan 21, 2013 2:35 am
daywalkerJoined: 09 Nov 2007Posts: 6108Location: Hatertown
Apparently this post - and only this post - is now missing from my blog. Backups aren't restoring. I have no idea how you lose just one post, but there you have it.
So irritated right now.
_________________ GREAT UNITER / ORACLE / ELDER
MOOAAR DONGS
Alex
Posted: Mon Jan 21, 2013 6:21 am
Joined: 18 May 2006Posts: 3128Location: Roosevelt
Can you pull it off of archive.org?
tehschkott
Posted: Mon Jan 21, 2013 7:13 am
daywalkerJoined: 09 Nov 2007Posts: 6108Location: Hatertown
I’m now convinced a solar panel is the only way to make this work. I haven’t found a good one yet, but I’ve been looking at the Brunton Solaris 12. Puts out 12v, 800ma, weighs 11oz, and costs around $200~.
You'll want to buy that at REI my friend, REI. I attempted to use a SolarDuo strapped to my rear rack at RAGBRAI and it was near worthless. The sun was bright and my skin was tanned but two AAs could only get 1/4 charge on a full day of riding.
However, the little [Solar -> AA <-> USB] widget thing works just fine without the panels and is awesome for converting gas station batteries to cell phone power!
_________________ -Kevin
tehschkott
Posted: Wed Jan 23, 2013 6:49 pm
daywalkerJoined: 09 Nov 2007Posts: 6108Location: Hatertown
Gas station batteries aren't what I'd consider an acceptable option. How are gas station batteries supposed to help anyone in the mountains?
I sorta replied to the solar thing in the comments of the article but:
Quote:
...Powering a low-speed touring rig presents some unique challenges. Dynamo lighting only works when you have a lamp with a strong standlight (and preferably a non-STVZO lensed light). Battery only works if you can figure out a way to charge the batteries; you can’t use a dynamo USB charger on a mountain tourer because you must maintain moderate speeds for long periods of time (conditions not commonly found on a mountain tourer), solar panels are expensive and require open access to sunlight. However solar panels are getting cheaper and more efficient - I just don't know if they're there yet. Solar may be the best bad option on the table right now.
Maybe someone wants to send me some solar panels to evaluate? AHEM.
Other options for charging might come out of emerging thermal technologies. Power Pot (http://www.thepowerpot.com/) for example uses thermal energy to generate electricity, an idea I’ve been intensely interested in for years now.
However, the little [Solar -> AA <-> USB] widget thing works just fine without the panels and is awesome for converting gas station batteries to cell phone power!
If you want something to charge on your laptop, bring on a weekend ride to keep your gps or cell topped off:
https://www.sparkfun.com/products/11359
(available in 3 different sizes, 1,000mAh, 2,000mAh, 6,600mAh)
Anybody have experience with the AXA Luxx70 Plus?
I like it on paper because it has USB charging but is way less expensive than the B&M Luxos U. We're talkin half the price less. I'm also liking how the USB port is self-contained on the light itself. I don't really care that you can only use the USB when the light is off, and I'm willing to accept that the USB port probably won't charge anything for shit unless I'm going a steady 10-12mph+.
whoreratiocane
Posted: Thu Jan 23, 2014 4:35 pm
Joined: 12 Aug 2010Posts: 190Location: Florida
I have the AXA Nano 50 plus with the self contained USB. I think that it is a good light, but I have not used the USB. Pm me if you want to check out one that is hooked up.
_________________ YEAAAAAAAAAAH!!!!!!!!!!!!
caustic meatloaf
Posted: Thu Jan 23, 2014 5:31 pm
Joined: 06 Dec 2010Posts: 1235537Location: a hammy melange...
What's the MSRP on that? I've been eyeballing the one below, but haven't mustered the will to pull the trigger on it yet, since it's about $200.
I found this...
http://www.lxs-bike.de/headlamp-luxx70-plus,3,87,1999978989
after shipping and this weird VAT thingy it's 101 euros. so what's that, like $140? Shipping doesn't increase when I increase the quantity so maybe we can get a big order going and save some euros.
Warning: I have not confirmed I can actually purchase it from this site at this price into this country with my bank account.
blasdelf
Posted: Thu Jan 23, 2014 5:54 pm
BAD NAVIGATORJoined: 01 Mar 2010Posts: 1505
archie wrote:
I don't really care that you can only use the USB when the light is off, and I'm willing to accept that the USB port probably won't charge anything for shit unless I'm going a steady 10-12mph+.
The problem with it is that it has a naive charging circuit that leads to a degenerate death spiral -- if your speed ever dips around the threshold speed, your phone will start waking itself up repeatedly, rapidly draining the battery. This is because the charger starts output as soon as its buffer capacitor is full, even if it can't keep it topped off enough to charge for more than a few seconds.
And you're only going to get a ~25% charge in an hour of continuous cycling at that speed with no intersections or real climbs.
The Luxos U doesn't have the hysteresis problem because there's a microcontroller and lifepo battery in there, and it also has the turbo mode that makes use of those same components for radness.
Paying the nerd price the Luxos U is around $160, the AXA is around $90 and has less availability. If that's your budget for a light I think you should get the Cyo Premium instead for around $70.
caustic meatloaf
Posted: Thu Jan 23, 2014 5:58 pm
Joined: 06 Dec 2010Posts: 1235537Location: a hammy melange...
Hmm. Where can I get the nerd price? $160 is definitely cheaper than $190.
_________________ HIS NAME IS EDMUND
archie
Posted: Thu Jan 23, 2014 6:00 pm
Joined: 21 Jul 2011Posts: 149Location: cloud nine
blasdelf wrote:
The problem with it is that it has a naive charging circuit that leads to a degenerate death spiral -- if your speed ever dips around the threshold speed
archie
Posted: Thu Jan 23, 2014 6:09 pm
Joined: 21 Jul 2011Posts: 149Location: cloud nine
Hmm, thanks Fred. That complicates things sufficiently. I guess I will just return to riding my dynamo hub without a light as I continue to dither.
caustic meatloaf
Posted: Thu Jan 23, 2014 7:49 pm
Joined: 06 Dec 2010Posts: 1235537Location: a hammy melange...
archie wrote:
Hmm, thanks Fred. That complicates things sufficiently. I guess I will just return to riding my dynamo hub without a light as I continue to dither.
Hey now, I'm already part of that team. DO YOU KNOW THE SECRET HANDSHAKE?
_________________ HIS NAME IS EDMUND
Bo Ttorff
Posted: Thu Jan 23, 2014 11:12 pm
GO SEAHAWKS!! 12 for LYFEJoined: 20 Jul 2011Posts: 3092Location: King County
Random fact: I went to high school with Blake from workaholics
_________________ -housed white guy
archie
Posted: Fri Jan 24, 2014 6:35 pm
Joined: 21 Jul 2011Posts: 149Location: cloud nine
caustic meatloaf wrote:
archie wrote:
Hmm, thanks Fred. That complicates things sufficiently. I guess I will just return to riding my dynamo hub without a light as I continue to dither.
Hey now, I'm already part of that team. DO YOU KNOW THE SECRET HANDSHAKE?
Nooo...All this time I thought it was just the WINK
Jake that's awesome. Do you remember what he was like? Bring him out on a ride sometime!
archie
Posted: Fri Jan 24, 2014 6:38 pm
Joined: 21 Jul 2011Posts: 149Location: cloud nine
And please tell me you made fun of his curly hair???
GO SEAHAWKS!! 12 for LYFEJoined: 20 Jul 2011Posts: 3092Location: King County
It wasn't as long back then. Always a pot head, we had a drama class together. Nah, never made fun he was always cool and awkward.
_________________ -housed white guy
blasdelf
Posted: Mon Jan 27, 2014 5:11 pm
BAD NAVIGATORJoined: 01 Mar 2010Posts: 1505
archie wrote:
blasdelf wrote:
The problem with it is that it has a naive charging circuit that leads to a degenerate death spiral -- if your speed ever dips around the threshold speed
I can confirm that the user experience is EXACTLY like this with that sort of charger
trying to unplug a device furiously beeping its cries of battery death, while climbing at 10mph or descending at 40
blasdelf
Posted: Mon Jan 27, 2014 5:20 pm
BAD NAVIGATORJoined: 01 Mar 2010Posts: 1505
caustic meatloaf wrote:
Hmm. Where can I get the nerd price? $160 is definitely cheaper than $190.
Here it's €100 with the 19% tax deducted, around ~$135 in our currency. Shipping is a flat €20.
I’m now convinced a solar panel is the only way to make this work. I haven’t found a good one yet, but I’ve been looking at the Brunton Solaris 12. Puts out 12v, 800ma, weighs 11oz, and costs around $200~.
You'll want to buy that at REI my friend, REI. I attempted to use a SolarDuo strapped to my rear rack at RAGBRAI and it was near worthless. The sun was bright and my skin was tanned but two AAs could only get 1/4 charge on a full day of riding.
However, the little [Solar -> AA <-> USB] widget thing works just fine without the panels and is awesome for converting gas station batteries to cell phone power!
I'd recommend the Joos Orange, also available at REI. The performance is actually useful (full charge after a full day's ride on a mostly cloudy day), and it's rugged as all get-out. Survived a tour in Afghanistan and a few week long bike camping trips. My only dislike is that it's kinda tricky to get it mounted on a rack. I use a bungee net to hold it, my tent and an Alite camp chair rolled up. Charges to a 5000 mAh battery, and outputs to your choice of 20 cm long attachment cables for most major electronic devices.
But it's way better than anything that Brunton or Goal Zero make, hands down.
All times are GMT - 8 Hours
The time now is Fri Aug 11, 2023 8:59 am
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
daywalker
Joined: 09 Nov 2007
Posts: 6108
Location: Hatertown
GO SEAHAWKS!! 12 for LYFE
Joined: 20 Jul 2011
Posts: 3092
Location: King County
Joined: 06 Dec 2010
Posts: 1235537
Location: a hammy melange...
Joined: 18 May 2006
Posts: 3128
Location: Roosevelt
Joined: 19 May 2009
Posts: 323
Location: monkey lab
Joined: 28 Jul 2007
Posts: 1315
Location: Columbia City
BAD NAVIGATOR
Joined: 01 Mar 2010
Posts: 1505
Joined: 21 Jul 2011
Posts: 149
Location: cloud nine
Joined: 27 Jan 2007
Posts: 1879
Location: Westlake
Joined: 01 Mar 2010
Posts: 2098
Location: Greenwood
Joined: 12 Aug 2010
Posts: 190
Location: Florida
rookie
Joined: 20 Aug 2007
Posts: 1173
Location: Sur le nord-ouest des États-Unis, pret de la frontier Québécois
