Thorn Cycles Forum
Technical => Lighting and Electronics => Topic started by: Slammin Sammy on February 27, 2015, 09:27:04 pm
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Here's one that I didn't expect:
My wife's Son28 hub has developed a distinct vibration when the light (B&M Lumotec IQ2 Luxos B) is on. It's smooth when the light is off, although I can hear a quiet ticking from inside the light.
The light pulses if she is going slow, a phenomenon I don't see on my bike, with identical hub and U model headlamp. We're both running Toplight Line Brake Plus rear lights.
Any ideas?
Thanks,
Sam
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Any ideas?
Yep, sure do. The vibration comes from varying internal magnetic current eddies, and will vary under electrical load (it is load-specific) and worse in some SON dynohubs than in others or other brands (the SON Deluxe seems to suffer less). Do you know which SON28 your both have? The SON28 Klassik tends to have a bit more vibration than the SON28 New in my experience.
The vibration bothers the hands of some more than others. You'll probably not notice it much on chip-seal or rough asphalt, and might on concrete or smooth paving.
Much of it depends on the stoutness of the forks. Heavy, stiff ones seem to transmit less vibration.
One key factor in SON dynohub vibration is how tightly the hub is fastened. If it can rattle *at all* in the dropouts, it is made worse. I noticed I could *not* address it with the hex-key bolt-on skewer supplied with my Sherpa and Nomad, and replaced those with a Shimano q/r. Problem almost completely solved, with only the lightest of vibrations on the smoothest of roads noticeable on either of those bikes After the change.
I'd suggest tightening the skewer (8-10 N-m according to specs in your supplied manual or on the SON site here: http://www.nabendynamo.de/produkte/pdf/english/son282013e.pdf ) and if that doesn't help, then changing to a standard internal-cam quick-release should. Just be careful not to do it up too tightly. I made the switch from the original bolt-on skewer for the really rough roads I ride.
A loose headset can make dynohub vibrations more noticeable, too.
However, in this case I think there's something else going on...
The light pulses if she is going slow, a phenomenon I don't see on my bike, with identical hub and U model headlamp.
Yep, normal in a standard dynohub-powered LED when going slow, not so much in the Luxos Model U, thanks to smoothing circuitry and an internal rechargeable battery. The difference here between your two Model U's may signal a problem with hers. I suspect the low-speed beam-shaping circuitry (that alters the beam with speed in response to pulses counted off the hub) may not be working properly. This was a problem in some Model U's from what I've read on various Dutch and German forums.
Be aware, sometimes The Toplight Line Brake Plus taillights don't always play nicely with some headlights...and I've seen it sometimes happen also in when different production runs of head- and taillights are matched together. Check the wiring and mounting for her taillight as well. Any taillight that must be or is grounded to the frame via its mounting bolts will not work with a Luxos. Please check real close: Is hers called the "BrakeTec" taillight? Peter White notes... (1) First, a few of the original version of the Busch & Mόller Toplight Line Plus BrakeTec are not compatible with the Luxos U. Actually, many of these taillights will work just fine, but a few won't, due to slight variations in the tolerances of one electronic component in the taillight. Given the complex nature of that taillight as well as the Luxos U, there is sometimes a problem, and the two lights ought not be used together without first being tested during daylight hours. The new "pulsating" version of the BrakeTec works fine with the Luxos U.
(See: http://www.peterwhitecycles.com/b&m-hl.asp ). Taillight polarity is also an issue for this headlight. Peter White again: Even with a compatible taillight, you must be careful to maintain the correct polarity between the Luxos U headlight and the taillight. As of this writing, Sept 2014, there are four taillights that will not function properly if you reverse the polarity between the headlight and taillight. These are the Toplight Line and Toplight View taillights, and the Toplight Line Brake Tec and Toplight View Brake Tec taillights. If you should reverse the polarity, the standlights will not work, and in some cases the taillight will not work at all!
So, + on the headlight must be connected to + on the taillight, and - on the headlight must be connected to - on the taillight. This is critical!
One last caution from him at the same link: At the bottom rear of both Luxos headlights are four 2.8mm connectors. Two are labeled "in" and two are labeled "out". You must connect the wire from the hub dynamo to the two connectors labeled "in". If you connect the hub dynamo to the "out" conectors, the headlight will not function properly.
If you choose not to use a wired taillight, it's no problem. Just connect nothing to the "out" connectors.
And, since the little male connectors are emdedded in the rear of the Luxos housing, it can be a bit awkward to install the wires once the headlight is mounted on the fork. I recommend connecting the hub and taillight wires to the Luxos before mounting the Luxos on the fork crown.
I think the pulsing low-speed output with her light *and* the vibration may be a sign of a taillight mismatch or circuitry problems within the headlight -- or both -- but that's my best guess at this point. The quiet ticking inside the light intrigues me mightily. We'll know more if you can check the taillight mounts and wiring and confirm the model and production date of the lights and check with either your dealer, B&M, or Peter White.
Some models of the Luxos U (particularly the early production runs) were found to be problematic in a variety of ways and I understand from various German fora, production was interrupted for a time to address some of the initial problems.
Hope this helps.
All the best,
Dan.
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Yeah sometimes I will be coasting down a long hill with patches of trees along the way, moving in and out of the sunlight. I have my headlight switched to auto mode, so it will turn itself on in the shady stretches then turn itself back off in the sunny parts. It's subtle but I can feel that through my hands, the slight vibration from the light. I think the load on the dynamo is greatest when the light first turns on and the capacitor is charging up. It seems like the vibration is most intense for maybe five seconds and then it fades away almost entirely.
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Thanks guys,
I will recheck all the wiring very carefully as soon as I get a chance, but I stress that this phenomenon has developed over time (according to SWMBO).
Also, just to clarify, she has the B model of the Luxos. Mine's the U model. Hers is newer.
Sam
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I get a gentle hum and v slight vibration when coasting down smooth Tarmac hills above 20 mph. As usual Dan has the explanation covered.
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No vibration here, heavy 2.25 width tires on the heavy Andra 30 rim on a stout Nomad II fork probably would insulate any vibration. Plus, I use a different dynohub.
I would have assumed that all current was AC, not DC. I had no idea that some taillights had a polarity issue. (I use a battery taillight so I would not have any reason to know that.)
Do all headlamps that have connectors for a taillight have rectified current? If so, I wonder if in my home brew USB power supplies, if I could skip using a rectifier and pull power off of the tail light circuitry? I suppose if I did that, since the tail light probably has a 0.6 watt rating, I would overload any rectifier in the lamp unit.
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I would have assumed that all current was AC, not DC.
*Most* bicycle dynamos (not all; some have rectifiers inside) produce AC current.
In terms for a general audience...
With incandescent bulbs, it doesn't really matter (well, it can...using rectified [DC] current reduces particle fragmentation of the tungsten filament and brightness is affected to a degree).
With LEDs, it does matter. They're diodes (Light Emitting Diodes), which work a bit like one-way valves for electricity, so polarity is important.
LED headlights have internal rectification -- circuitry inside changes the Alternating Current (AC) to Direct Current (DC) to run themselves. Since the current is already being rectified for the headlight, then it makes sense to tap into that and supply DC to the taillight. If the taillight is also an LED, then all is good, but polarity should be observed. If the taillight is an incandescent bulb, then it doesn't really matter either way.
The problem is, not all LED headlights supply rectified current to taillights, and not LED taillights have their own rectifiers internally (and why should they, if attached to a headlight that supplies what they need?). When people mix and match headlights and taillights, sometimes a mismatch occurs.
Do all headlamps that have connectors for a taillight have rectified current? If so, I wonder if in my home brew USB power supplies, if I could skip using a rectifier and pull power off of the tail light circuitry? I suppose if I did that, since the tail light probably has a 0.6 watt rating, I would overload any rectifier in the lamp unit.
No, not all headlights have rectified current for the taillight.
Worse, not all taillights have their own rectifiers and if they do, they may or may not have *current* limitation.
Beyond that, not all LED taillights (with or without their own rectifiers) have *overvoltage* protection. Those that do will have it at varying levels. Those that don't will fail from overvoltage if the headlight fails for some reason. Because of the mismatch possibilities, most taillights with overvoltage protection are also current-limited. Sometimes it is a matter of fitting a more tolerant LED, rather than via circuitry. I have learned this through autopsying various taillights.
The B&M Luxos U headlight is a special case among special cases. It will only work with certain taillights, and polarity of the taillight connections *must* be observed. Complicating things further, the brake light version of B&M's Toplight Line Plus really has nothing to do with braking. It interpolates the need to signal braking by counting an abrupt change in AC pulses coming from a rapidly slowing dynohub.
Similarly, Supernova taillights are not fully compatible with other brands. For example, you can pair Supernova TL2 taillights with other brands of headlights...but if you do, the taillight's standlight function won't work (that function is in the Supernova headlight). B&M taillights don't play well with Supernova headlights.
The permutations of what works with what are mind-boggling and can change over time as the internals of the lights are changed in production, sometimes without notice. For example, the B&M Toplight View Plus (different from the LinePlus) taillight *will* work with the B&M Luxos U, but not a Supernova headlight. It does have full over-voltage protection to preserve it in the event of a headlight failure. I'm in the process of developing a table that removes some of the mystery, but it is hard and sometimes expensive work for an individual to do.
Occasionally, a bicycle owner will get the idea to use piggyback connectors and power an LED headlight and taillight independently directly off the dynohub. That doesn't always work -- the taillight might require rectified current (DC source) or it might get overvolted by direct connection. It very much depends on the taillight being used, and even examples from various production runs can differ. On my Extrawheel trailer with SON28 dynohub and e-Werk charger, I wanted a dyno-powered taillight but had no need for a headlight. To power that taillight, I had to make a voltage rectifier and voltage limiter for my Toplight Line Plus -- I couldn't hook it up directy. Being an LED powered by a rectified source (of my own design), I had to observe polarity or it wouldn't light.
Taking charger power off a dyno-powered taillight is very much a mixed bag, and if amp draw of the downstream device exceeds what the taillight can supply, nothing in the system is going to be very happy. It is best to get charger power direct from the hub unless you are using a headlight with built-in USB charging (i.e. B&M Luxos U, Axa Nano).
Here's what I've found works best and has proven to be most reliable if you use separate headlight and charger units:
For charging purposes, take the electrical feed directly off the dynohub, using piggyback connectors. It is tempting to tap into the light wire for powering the charger because it looks neater, but it usually means the lot has to be redone if one or the other components fail or are upgraded. This is ever so much more difficult if it happens while on tour and more time consuming if at home. If you tap into existing wiring, use reliable breakaway connectors so you can service things piecemeal.
Take the power for the headlight also directly off the dynohub; via piggyback connectors is okay.
Slave the LED taillight off the headlight designed to match and supply it.
Be cognizant of the limitations for connection within brands and avoid mixing brands. Supernova is "different" from other lighting and works best when paired with itself (i.e. Supernova headlight matched to one of their taillights for full compatibility).
Put another way, I run my lighting and charging systems in parallel/separately from the hub itself. It makes connections easier and more reliable and service is easier if I have to replace a failed component. I run my taillights in series (as far as hookup is concerned, though the internal circuitry may be parallel wrt to the board) in connection to the headlight.
Whew.
Best,
Dan. (...who's going to leave the keyboard for several hours to enjoy a corker of a blue-skied sunny day on his Nomad)
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Dan, thank you for the dissertation. I learned a lot.
I will continue to use a battery powered taillight.
Mixing a LED headlight (Lumotec Oval with switch, no stand light, no night sensor) with a USB charger is the limit of my exotic plans. I have soldered up a few USB chargers, have parts to solder up a few more experimental ones. My long term plan is to run them in parallel with the headlamp. If the headlamp is turned on, I will not plug anything into the USB port. If I have the light turned off, then I may or may not plug stuff into the USB.
Sometimes I run two LED headlights in series, when I do this I will not use a USB charger. This is mostly in the fall or winter when I am more likely to be out during dark hours. The lights are unswitched so I leave them on at all times. The lights I use when I use two in series are ones that were sold to be used for bottle dynamos, thus no switches were installed in the lights. I need a higher minimum speed to get usable light, but even pedaling up a 7 percent grade which is quite slow I get enough light to see where I am going.
I plan to use my wheel with the dynohub on two different bikes. I zip tied wires to the fork blade on each of those bikes, have a hub electrical connector at the dropout on each bike and at the fork crown end of the wires I have a pair of 2.8mm female spade connectors to plug my various electrical bits into. I bought a bunch of the 2.8mm connectors (M and F) so I can easily plug and unplug different parts from each other.
Not biking right now, the Doctor that did my shoulder surgery a month ago said I have to stay off the bike for 4 to 6 months, so it will be some time before I can report on the results of my solder skills making USB chargers.
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Hi mickeg!
Ooh, ouch, ow! I'm so sorry you've got the shoulder issue to deal with, and I hope it heals soonest.
While you're healing, "bike projects" will have to do, and yours sound fine to me. One one of my rando bikes, I'm running two of the PDW Radbot 1000 LED blinkys for long-range visibility on country lanes as I ride through the night. Yes, they're point-source emitters, but set to different blink patterns or solid-on, they do help me be seen in these circumstances and they avoided the hassle or need to run light wiring to the taillight. They are also great in daytime when riding in heavy morning or late afternoon commute traffic. On this bike, I will probably retain them after I go with a dyno-powered taillight, probably a Toplight Line Plus I picked up almost free on eBay.
Healing thoughts your way,
Dan.
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Mickeg,
I'm never averse to topping up from mains power for (re)charging gadgets when it is available. Like you, I use an outlet multiplier, but I also add an adapter that screws into a light fixture. Sometimes, it is impossible to get to outlets placed behind room furniture, but a lamp is almost always provided on the bedside table in most lodging and a screw-in adapter makes it a convenient source of power.
I also use a high-amperage multi-port USB mains charger that allows me to directly charge four gadgets at once at the fastest rate possible for each, minimizing the time needed to charge and the number of outlets required. Mine is the EasyAcc. Input is autoranging for international travel, so 100-240vac~ and 50/60Hz with output rated at 5.0vdc @ 4.0A total, distributed among the four outputs as: 1.3A, 1.0A, 2.1A, 2.1A. Obviously, not all outlets can operate at maximum draw simultaneously, but with a mix of devices, it has been fine. The plug folds in so there's nothing pokey/sharp that could hole a bag. USD$11 for the white version, both cheaper and easier to spot in a dimly lit pension than the black one: http://www.amazon.com/EasyAcc%C2%AE-Charger-Folding-Portable-Smartphones/dp/B00LWRKAR8
This has eliminated the need to get up in the night to swap items being charged from mains power on single USB charging port. My old strategy was lots of chargers on lots of outlets, multiplied as necessary to maximize charging. My new strategy saves weight, bulk, and needed outlets by using the multi-outlet USB charger. It works really well.
A reminder: A common cellphone USB charger can be used to also recharge other USB gadgets.
Photos attached below. You'll also see my Sanyo Eneloop USB recharger for AA/AAA cells. It does up to two at a time, and is a "smart" charger that works especially well with Panasonic/Sanyo Eneloop batteries thanks to a "pulse charge" circuit. I use standard Eneloops as well as their high-capacity "XX" versions for high-demand devices. My USB (re)charged AA/AA cells power my...
LED headlamp for wearing around camp at dark (toilet forays, cooking outside, reading in tent, fixing punctures at night)
LED red solid/flashing taillight(s)
LED white solid/flashing safety headlight (car drivers recognize blinking white = oncoming bike where I live)
SteriPen UV water purifier
Sony AM/FM/Weather radio
Garmin Oregon 400T GPS
Not all batteries are used at the same rate, so I don't need a full backup set. The most critical ones are those for the GPS and SteriPen, so I do carry a spare set for each. If I really needed to, I could raid spares from my other gadgets to power them.
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On a general side note...
Carrying a large pile (mains-rechargeable storage battery) is a viable alternative to a dynohub/dynocharging setup if you won't be away from mains power for long periods (days or weeks at a time). I use this alternative when touring with bikes that don't have dynocharging; it worked fine for me over 4 months' touring in Europe supplemented by one of my Joos Orange solar panels with a 5,400mAh accumulator battery. My battery is a 20,000 mAh rechargeable pile capable of charging and powering high-draw/high-drain devices including an iPad. I have confirmed both its capacity and efficiency in my tests. For use when touring with no other charger, it is good for three days or more of reasonably hard use before needing to be topped off again. It will power my phone continuously under heavy use for over 17 hours. It charges itself quickly and only from mains power; in 20 minutes it will grab enough juice to fully recharge my large screen smartphone from flat to full over the next hour while riding. This is particularly convenient when I have stopped at a cafe for a quick lunch and then need to get back on the road soonest. I'm not tied to the outlet back at the restaurant, waiting the hour it takes to recharge my phone from flat.
For many people taking shorter tours or touring in civilized areas, a large capacity rechargeable battery makes much more sense than a full dyno-charging setup when cost is figured into the picture. I paid USD$80 for mine at Amazon US, available for £49.99 in the UK. This is less cost than an inexpensive but effective "budget" dynocharging setup (i.e. Shimano dynohub in a built wheel from German eBay plus an AXA Nano headlight with USB charging), and a fraction the cost of a high-end dyno-charging system with lighting. It will also recharge any of the increasing number of USB head- and taillights, and serves as a source of direct power for extended usage.
After a lot of searching, I settled on the Anker 2nd Gen Astro Pro2 20000mAh Quad-Port External Battery: http://www.ianker.com/product/79AN7906-BA ...and... http://www.ianker.com/product/79AN7906-BA#sthash.cSlfbHwZ.dpuf ...and FAQ here: http://www.ianker.com/product/79AN7906-BA#ptop I have confirmed its efficiency and rated capacity in my own tests and it has given good service. When its mains charging unit failed in France last summer, I found a common replacement at a small electronics store outside Amiens; Anker sent me a factory replacement promptly and without quibble upon my return home. It is a smart charger, capable of charging each of three USB devices (4.5A maximum among the three) hooked to it at the maximum allowable individual device charging rate as well as supplying 9v @ 2A and 12v @ 1.5A. It is compatible with all Apple and Android smartphones, tablets (including the Nexus 7) and other USB-charged devices.
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While I have used batteries about as long as dyno power, I usually prefer dyno-charging because I often take much longer trips into remote areas where there is no power. I also like the satisfaction of making my own power while I ride or supplementing it from the sun...and I like playing with various means of charging and powering my gadgets. I prefer dyno-powered lighting and carrying fewer batteries if possible. That said, I often supplement dyno-power with buffer and storage piles. Last summer I would occasionally watch a movie on the phone in my tent before dropping off to sleep. Similarly, I'd sometimes read just a single chapter of an e-book on the phone screen before dropping off. I never lacked the battery power to do so and it worked out fine for me.
I have standardized on USB-chargeable gadgets requiring a nominal 5vdc @ 500mA-1.5A. This was a deliberate choice so I could keep things charged under my own power or recharged with mains power using an adapter or large storage battery. Sometimes, it doesn't take much to adapt a gadget. My daily Panasonic electric shaver only needed a USB male end grafted onto the charging cord. I may replace my chemical handwarmer with a USB-chargeable one for use in really cold weather. The weight is the same, and no butane or other fuel is required. I have a standalone charger for my spare phone battery, so I have no downtime if my primary battery goes flat.
Initially, I did not expect to find much in the way of gadgets suited for my needs, but soon found solutions that worked and their power requirements did not compromise their usefulness. For example, my large-screen phone (bordering on a phablet) meets my own touring needs better than a full-sized tablet would, independent of the power requirements (it is smaller and stowable in a jersey pocket and always with me). I now do most of my non-analytical computing on it. I used it to write this.
For me, going to USB-powered devices reduced the number and size of things I take and a common power source means any device can be replenished from any charger. In my case, "any charger" means a USB source powered by dynohub, solar, mains adapter, or large capacity rechargeable battery. A similar case could be made for standardizing on USB-charged AA/AAA cell-powered devices. Things are getting better in that regard -- rechargeable batteries are getting better, and devices are now designed for greater efficiency. My AM/FM/Weather radio runs on one AAA cell and lasts ~65 hours. I have a small MP3 player that goes nearly 100 hours on a single AAA. Such great efficiency means fewer batteries to carry and more reserve charging capacity no matter how you go about it.
Best,
Dan.
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Dan, thanks. I will research that USB powered Eneloop AA/AAA charger. I have been using some cheap USB powered AA/AAA chargers that instead of being smart just supply power very slowly so that they do not overcharge. Unfortunately that means 10 to 12 hours to charge the AA batteries. Would be nice to charge AA batteries faster when using USB supply. I have some splitter cables so I can plug several of those AA/AAA chargers into a single USB supply.
I have carried a faster AA/AAA charger to plug into power outlets on trips when I do not have a dynohub. Perhaps with that USB powered Eneloop charger I would not need that other charger if I could charge NiMH batteries faster on dynohub.
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I will research that USB powered Eneloop AA/AAA charger.
Mickeg,
Here is a fuller explanation of how the Eneloop USB charger works:
http://www.stefanv.com/electronics/sanyo_usb_charger.html
They've become rather scarce of late, but there's still some outlets still have stock on hand.
As for charging time, I've found I can bring two fully depleted Eneloop AA cells to complete charge in about 8 hours. The higher capacity Eneloop XX batteries take longer, close to 12 hours. I try to avoid fully depleting my rechargeable batteries, so typical charge times are about 4-6 hours to "top-off" a pair of AA cells.
I almost always have some battery on charge while under way, so my batteries have as much capacity on demand as possible.
Going for a extended periods completely off-grid with bike- or solar-powered charging requires a specific mindset, almost a lifestyle of integrating good charge/usage habits. I'd compare it to hypermiling in a car (driving for maximum fuel economy). Batteries add some flexibility to the process. For me, it adds spice and interest while touring in remote areas where sometimes there's a whole lotta Nothin' to pass through (Black Rock Desert or the Alvord, for example).
Much success with mixed charging comes from appropriate timing. If one is gong to be riding a lot during the day, the dynohub will be working regardless of weather or sun. Solar with accumulator battery will also charge during the day, but at a greatly reduced rate if it is cloudy or raining and solar doesn't care if you're moving or not and hills have no effect. I never draw from solar during the day; all converted sun goes into the accumulator batteries for use overnight. The dynohub stops when not moving or at night, and solar goes to sleep. That's when accumulator batteries can take over and provide a handoff charge while the rider is in bed. My windmill (inverted trailer with wheel vanes) requires about 16kph/10mph of windspeed for consistent power generation. It will actually spin with less if I hand-start it, but requires the full 16kph to overcome magnetic repulsion and self-start on its own. I think modifying the vanes might lead to improvement.
The goal is to keep on top of charging needs as much as possible with real-time power generation, then use accumulated energy to overcome gaps and continue the process when not riding and overnight. Power demands are a bit like a leaky bucket -- a few leaks don't matter so long as you can keep the bucket near full by pouring in more water. Stop filling the bucket, and it will drain dry and take a good while to replenish. A good illustration of the process is a shishi-odoshi, or Japanese deer-scarer:
(http://upload.wikimedia.org/wikipedia/commons/9/99/Shishiodoshi.gif)
[Source: http://commons.wikimedia.org/wiki/File:Shishiodoshi.gif ]
All the best,
Dan. (...whose interest in on-tour gadget power/charging rivals Bill C's interest in camp stoves)
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Apparently that Eneloop charger is discontinued and has been for a few years. The few new ones still for sale command premium prices.
While researching the Eneloop this morning I found a competing product, the Pixo C-USB which recharges AA and AAA NiMH batteries along with also charging Li Ion batteries. It is in current production and sells for the same as the cheapest new Eneloop charger out there.
This link has a good description of both the Eneloop and Pixo C-USB. It is a bit complex to read as the way this document is formated is that he updates the old document with additional information, so you have to search for what you are looking for. But at one point he actually compares charging times for each, so there is a pretty good side by side comparison.
http://www.crazyguyonabike.com/doc/?doc_id=9258
At the above link, the author talks about charging from a solar panel and what happens if the panel goes into total darkness, and then back into light. Presumably that would be the same as stopping biking, then restarting again with a dynohub. It suggested that the Eneloop charger would resume charging the AA batteries whereas the Pixo would not.
So, I am going to have to decide what to get, if anything. My old stuff is less efficient, heavier since I need to carry more batteries, but is functional. The Pixo would handle both NiMH and Li Ion so I could consolidate my charging gear a bit if I got that. The Eneloop would likely work well in stop and go traffic without needing to be reset. I am going to contemplate on this for a while.
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Thanks for the link, mickeg. I'll take a look in some depth next.
No problems to date using my Eneloop chargers with the dynohub direct (no buffer battery used in this case): Charging resumes right where it left off when I restart after stopping, say for a traffic light or after a lunch break.
Best,
Dan.
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Apparently that Eneloop charger is discontinued and has been for a few years. The few new ones still for sale command premium prices.
I bought one of them in March 2014. They place where I bought it (in Vancouver) still shows it, although it is currently on backorder.
http://www.ncix.com/detail/sanyo-eneloop-rechargeable-battery-usb-87-89581.htm (http://www.ncix.com/detail/sanyo-eneloop-rechargeable-battery-usb-87-89581.htm)
Dan, do you notice any loss when you "move" your energy from one battery to another? Is there any noticeable difference between charging a device directly from your dyno hub, versus charging a "buffer" battery from the dyno hub then charging your device at night from the buffer battery.
Like you, I am fascinated by the combination of electronics and self-generating power while biking. When I was a teenager, I had a bottle generator that rubbed on the side of tire, powering a regular (non-LED) headlight. It was a lot of work, and not much light. When I got my first battery-powered light, it was like "night and day". But what I really wanted was a universal power and connection system on the bike: one larger battery that powered everything on the bike (lights, computers, etc) using standardized connectors. It seems that we are converging on something like that, with USB being the standardized connector. I still would like a single larger battery that could power everything. It could be charged off the mains if necessary, and topped up from the dyno hub. I wonder if a single larger battery would be more efficient (or less) than smaller (AAA or AA) batteries in each device.
- Dave
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Dan has not answered yet, so I will put in my two cents worth. When you charge NiMH batteries, they get warm. When you drain them, they also produce heat, but not as much. Thus some of your energy goes into heat and is lost. Li Ion also loses some, but I think it looses less energy than NiMH.
For home charging of NiMH, I use an Accupower IQ328 charger. It will measure how many milliamps goes into the battery to charge it and it can also drain a battery, measuring how much came out. I have not bothered to estimate efficiency and how much is lost with it, but it would be possible to do so.
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Dan has not answered yet,
Still typing away on my phone... :D Dan, do you notice any loss when you "move" your energy from one battery to another?
Yes, there are always losses in these circumstances. There are also losses when charging a battery (source -> storage) and even some when drawing on the resources of a battery (some types also have circuitry to prevent full drain, so available capacity may be as little as 85% of calculated maximum...this seems to be a common limit to prevent damage to the pile).
The amount of loss can vary depending on battery type, load, circuitry, and a number of other variables. From what I've seen in manufacturer literature, generally somewhere around 71% net efficiency is considered to be pretty good, as a thumbnail figure, but it varies. Is there any noticeable difference between charging a device directly from your dyno hub, versus charging a "buffer" battery from the dyno hub then charging your device at night from the buffer battery.
Well...yes, but this is really three questions and not two. :D
1) Yes, charging a battery direct from a dynohub via charger *may* be most efficient.
2) If the buffer battery is a pass-through type and the capacities and demand are matched, charging efficiency at the gadget may come close to direct charging from a dyno source, or it may be less efficient. All things being equal, ganged charging through a buffer battery could reasonably be expected to be less efficient than direct charging. Part of it depends on whether the pass-through buffer battery is fully charged or not and how often it is called into use (say with frequent stops or crawling uphill at slow speed. In these circumstances, the buffer battery will also need to be charged and the source may be unable to maintain equilibrium, so a net overall loss may occur).
A key determinate here is use. If you just want to use the buffer battery to *power* a device intermittently (gap-filling when dynopower would otherwise be too little), that is different from using the buffer battery to power *and* charge a device. Sometimes the device may draw so much power in use it cannot also be charged. Conversely, a device may draw too much current to be operated solely by the dynohub, and one must be content with charging the device's battery while it is powered-down. Sometimes, a buffer battery only works in the system as a way to slow the rate of overall drain, thus extending the service life of the gadget. I sometimes do this when using my GPS for all-day track-making. I then make up the loss by charging overnight from my solar accumulator batteries or from my large mains-rechargeable pile. This way, I don't start the day with an energy deficit that would only become worse.
3) When I charge an item while in camp at night, the storage battery is a "buffer battery" of sorts, but not by intent. The source/storage battery is really an accumulator battery and instead of passing current through and being ready to step in as a gap-filler on a charging system, it instead has been used as an electrical reservoir to accumulate energy to either draw upon directly to power a device while at rest or to recharge another battery. Without knowing the particular setup and combination in use, here again 71% efficiency in energy transfer seems to be considered a "good" figure, possibly about the best one can hope for in practical usage. Kinda depends on how one defines "efficiency". it most often is taken to mean energy lost when going from a source to a storage battery.
To put a twist on an old phrase, "You can never be too rich or too thin or have enough power in reserve". having more than enough energy at your disposal makes losses much less worrisome or problematic. Like you, I am fascinated by the combination of electronics and self-generating power while biking. When I was a teenager, I had a bottle generator that rubbed on the side of tire, powering a regular (non-LED) headlight.
This brings back memories. When my father and I would tour together, we used Union 9814 bottle dynos with rollers set to use the tire sidewalls. Drag from their plain bushings alone was so high we called them "drag brakes" and "retro-rockets". Efficienty was also low and light output from the incandescent bulbs was miserable. Their one virtue was relative reliability compared to the competition at the time, though I always thought Soubitez was better and Lucifer and Miller bottle dynos were much better but unobtainable for me. They were nowhere to be found in US bike shops in those pre-Interweb days.It was a lot of work, and not much light.
:D Agreed! Then, what light there was, became less as the filament coated the bulb globe and got dimmer and dimmer. Or blew on fast descents. This was how I came to make my first voltage limiter, back in the day. When I got my first battery-powered light, it was like "night and day". But what I really wanted was a universal power and connection system on the bike: one larger battery that powered everything on the bike (lights, computers, etc) using standardized connectors. It seems that we are converging on something like that, with USB being the standardized connector. I still would like a single larger battery that could power everything. It could be charged off the mains if necessary, and topped up from the dyno hub. I wonder if a single larger battery would be more efficient (or less) than smaller (AAA or AA) batteries in each device.
I share your desire, but here is where we run into trouble: The USB standard is fine, but the connectors aren't weatherproof, and I have a big quibble with that. Practically, the touring cyclist must shield the USB connection by placing it under cover, usually in a handlebar bag.
Actually, I do have a problem with the other part of USB, and that is the limited voltage and current supplied by the USB 2.0 standard, a nominal 5.0vdc @ ~500mA. It works, but it can double or quadruple the charging time of high-draw gadgets designed to "quick-charge" on mains power using ~1.5A-2.0A of current. If you have the time for charging and select your gadgets carefully, you can do well. However, things could be even nicer if we had that 12v SON dynohub that operates at roughly twice the current. I think we may get there eventually, via the need to power/charge high-draw/high-drain devices that are growing ever more power hungry.
Ultimately, the limiting factor is the human powering the lot. If drag is increased too much, it will begin to take away from the riding experience and become "too much work". Right now, we're doing about the best we can with what we have in terms of 6v/3w dynohubs. Shutter Precision claims higher efficiency with less drag on their dynamos, and of course dynamos that produce less power like the SON Deluxe have less drag than the SON28 Klassik or Neu, but the difference is pretty slight in real-world use. I think the next breakthrough will come in terms of greater circuit efficiency in gadgets to be charged and in better technology. I'd really like to see practical, small fuel cells come to market. That would solve many problems and perhaps completely obviate the need for dynocharging. Battery technology is holding back the entire electronics industry. If we only had more efficient power sources.... Some visionaries in the battery industry have wondered if supercapacitors might someday take the place of batteries, but that idea has problems when scaled.
My Anker mega-storage pile comes closer to your goal, but it is not bike-(re)chargeable and requires mains power to fill. This is the Achilles heel of most large storage batteries when combined with on-bike charging: They simply require more power to charge than a dyno charging system can supply. Too, many such batteries have charging "trigger" circuits and won't even allow charging unless the supply meets requirements.
One thing to keep in mind: A "big" battery is rarely a single battery. Instead, it is most often comprised of a number of smaller cells that are ganged to supply the needed power. You can see a bit more how this works in my background discussion of the Tout Terrain/Cinq5 SmartPower II, here: http://www.thorncycles.co.uk/forums/index.php?topic=10387.0 An aside: If you have time some rainy Sunday afternoon, take apart a PP3 9-volt battery. I do this sometimes to use the 6 AAAA (four "A's" @ 1.5v each) batteries for projects. They are an LR61 size, similar to the LR8D425 AAAA cells used in medical equipment. Most Alkaline 9-volt internal cells are round. The carbon-zinc and a few Alkaline internal cells are rectangular. Their usefulness depends on how you want to repurpose them.
It is entirely possible to charge what amounts to a "big" battery by individually charging the smaller cells that compromise one of your own making. I've done so, with reasonable success and little practicality. Charge enough AA cells and then put them in holders wired appropriately with a controller, and you end up with a battery that would be too large to charge if you tried to do so direct from a dynohub. Charge the components separately and you can manage, but it will take time. Depending on demand, it might not be practical to try. It wasn't for me. I did the math in advance, then went ahead and tried anyway. It certainly "worked" and I had a "big battery" sufficient to power a netbook through it's charging socket, but it took forever to accumulate enough power in pieces to do so and it weighed a lot and wasn't small. That's when the phone began to look like a Much Better Idea and I went that direction. You pondered...I wonder if a single larger battery would be more efficient (or less) than smaller (AAA or AA) batteries in each device.
...and the answer lies above. *Charging efficiency* appears slightly better with fewer aggregate losses if mass charging a lot of ganged cells compared to individual ones (according to battery company data I recall seeing), but then you run into the problem of a battery too large to charge by bikie means. There's lots of other issues related to rate of charge and the charge-characteristics of different kinds of batteries, also.
All the best,
Dan. (...who can usually be seen charging ahead... ;D)
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Dave,
Here's another way to look at it: So long as there is sufficient power supplied, a USB device doesn't "care" where it comes from.
The losses in efficiency translate practically into lost capacity when you transfer a charge. Effectively, not as much comes out as went in.
Best,
Dan.
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Thanks for your great answer, Dan. My question about efficiency was more from a practical point of view than a theoretical point of view. If I am the source of power (using a dyno hub), I don't want to waste my energy. If each battery is 75% efficient (that is, total output = 0.75 * total input), then each time I transfer the energy from one battery to another means that I need to generate 1/3 more power overall. To get 1 unit of energy out of the battery, I need to put in 1/0.75 = 4/3 units into the battery. If I store the energy in one battery first, then use that battery to charge my device later, then I would need to put in 1/(0.75^2) = 1.78 units in order to get 1 unit into my device.
By the way, when I said "buffer" battery, I meant what you call a storage or accumulator battery: charging the battery while riding, then using it later to charge a device. I wasn't thinking about chaining the batteries while they were being charged.
- Dave
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Those interested in choosing batteries may wish to look at this resource, as it squares with much of what I have found to be true in practice: http://www.powerstream.com/NiMH.htm
The information here is devoted to NiMh batteries, like Eneloops. Faraday efficiency for NiMH batteries is about 66%. As the author notes, "...you must put 150 amp hours into the battery for every 100 amp hours you get out. The faster you charge the worse this gets", so there is a real disincentive to uncontrolled fast-charging; it is better to use a "smart" charger.
Eneloops are a LSD (Low Self-Discharge) battery, which helps because they hold a residual charge longer than other types if NiMH, which can progressively lose charge while stored. One reason I switched to them is they require almost no maintenance and topping-off between uses. Other good brands of LSD NiMH batteries include Tenergy Centuras and Powerex Imedion. http://www.candlepowerforums.com/ is a terrific resource for battery discussions, and http://michaelbluejay.com/batteries/nimh-brands.html provides a good overview of NiMH batteries as well.
Best,
Dan.
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I use the Eneloops in my DSLR cameras, they seem to perform much better than anything else. But for touring where I am charging batteries and using them within a few days I find that cheaper batteries work fine. Most of my other (non-Eneloop) NiMH batteries are about 10 years old and have lost a little bit of capacity, but they are good enough so I am still using them.
Regarding how good Eneloops are, at my nieces wedding I changed my batteries in my camera about 15 minutes before the ceremony to make sure the camera did not fail at the wrong time. The batteries I took out were probably half discharged. The professional photographer 's flash ran out of battery power soon after that and someone at the facility where we had the wedding had picked up her spare batteries so she was virtually out of power. I loaned her my half discharged Eneloops and they powered her flash for the rest of the evening.