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  1. #1
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    Solar Panels for touring

    I'll be doing a three week trip next year mostly away from the grid. I've thought about dynohubs, but solar seems to be getting to the point where it is very competitive.

    This is a 14W anker solar panel , though how it's 14-watt when it's also max 5V/2A I'm not quite sure.

    Nonetheless, for $75 US it looks like a great deal, maybe a panel that can be used on the bike (though it's large), but also maybe a panel that is good enough to give you a significant boost just being used in late afternoons.

    Anything better out there? I'll probably just be charging iphone/ipad mini/lights.

    Not interested in dynohubs. I've gone that route before.
    Last edited by northerntier; 11-07-13 at 09:15 AM.

  2. #2
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    Quote Originally Posted by northerntier View Post
    I'll be doing a three week trip next year mostly away from the grid.
    Are you really going to be away from any electrical outlets for 3 weeks?

    Solar is very optimistic.

    It requires good positioning, large area, lots of sun, and lots of time, . Since much of your time in the sun is going to be spent riding, the first two issues are going to be hard to accomodate. The third is not entirely reliable (depending on where you are).

    If you not actually going to be in a place with no outlets, I'd suggest getting a battery recharger.
    Last edited by njkayaker; 11-07-13 at 10:46 AM.

  3. #3
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    Quote Originally Posted by njkayaker View Post
    Are you really going to be away from any electrical outlets for 3 weeks?

    ...

    If you not actually going to be in a place with no outlets, I'd suggest getting a battery recharger.
    No, I'm sure there will be time where I have power, but certainly I expect to go days w/o, and sometimes I do multi-day hiking trips as well.

    I will be taking at least one large (15,000 mAh) battery.

  4. #4
    Senior Member westrid_dad's Avatar
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    You may want to take a look at this thread as well.

    http://forums.adventurecycling.org/i...?topic=11752.0

  5. #5
    Senior Member dougmc's Avatar
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    Quote Originally Posted by northerntier View Post
    I will be taking at least one large (15,000 mAh) battery.
    15 Ah is only half the story of how large the battery is. How many volts at 15 Ah? Or how many Watt hours?

    A 15 Ah 12v lead acid battery is quite large (9 lbs?) and has a lot of energy. A one cell (3.6 to 4.2 volts) Li-ion 15 Ah battery is much smaller and has much less energy -- and they're very often mislabelled and have only a small fraction of the capacity they claim to have.

    You might want to test to see how many times you can charge your devices from what you've got before the trip.

    As for the solar panel, that would be pretty neat if you had it set up and charging while you rode. Though that one you are looking at seems too large for that.

    though how it's 14-watt when it's also max 5V/2A I'm not quite sure.
    Probably the solar panel can deliver 14 watts maximum (direct, summer noon-time sun), but the circuits that convert to 5v are far from 100% efficient.
    Last edited by dougmc; 11-07-13 at 12:24 PM. Reason: grammar

  6. #6
    coprolite fietsbob's Avatar
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    just remember the solder bridges to connect the elements together take up surface area
    and generate no power.
    so 100% efficient .. is as achievable as honest politics or Just-Wars.


    so are the Tours about the trip, and the Journey,
    or just keeping the I phone addiction fed, off the grid
    while away from home?
    Last edited by fietsbob; 11-30-13 at 11:02 PM.

  7. #7
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    Quote Originally Posted by dougmc View Post
    15 Ah is only half the story of how large the battery is. How many volts at 15 Ah? Or how many Watt hours?

    A 15 Ah 12v lead acid battery is quite large (9 lbs?) and has a lot of energy. A one cell (3.6 to 4.2 volts) Li-ion 15 Ah battery is much smaller and has much less energy -- and they're very often mislabelled and have only a small fraction of the capacity they claim to have.

    You might want to test to see how many times you can charge your devices from what you've got before the trip.

    As for the solar panel, that would be pretty neat if you had it set up and charging while you rode. Though that one you are looking at seems too large for that.

    Probably the solar panel can deliver 14 watts maximum (direct, summer noon-time sun), but the circuits that convert to 5v are far from 100% efficient.
    It appears that he's talking about USB (5 volts at 1-2 amps).

  8. #8
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    Quote Originally Posted by northerntier View Post
    No, I'm sure there will be time where I have power, but certainly I expect to go days w/o, and sometimes I do multi-day hiking trips as well.

    I will be taking at least one large (15,000 mAh) battery.
    Don't know what "multi-day" means.

    That sort of USB charger should be enough for a few days (even 4-5, with some care).

  9. #9
    Senior Member dougmc's Avatar
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    Quote Originally Posted by njkayaker View Post
    It appears that he's talking about USB (5 volts at 1-2 amps).
    Obviously, but his point was probably is that 5 volts at 2 amps is 10 watts -- not 14 watts.

    Having everything being charged through mini-USB ports is convenient, but it also means that everything needs to be bumped up or down to 5 volts, which introduces inefficiencies. But for the most part, the convenience makes it worthwhile.

  10. #10
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    Quote Originally Posted by dougmc View Post
    Obviously, but his point was probably is that 5 volts at 2 amps is 10 watts -- not 14 watts.
    Yes, the output is limited to 10 watts.

    I sort-of skipped over that question because even 10 watts is probably more than one could expect typically.

    The "14 watts" would seem to be an indirect reference to the size/amount of the solar collectors (the maximum power they can produce in optimal conditions).

    That is, the collector is larger than "10 watts" so it has some chance of producing "10 watts" in more realistic (less than optimal) conditions.

    Quote Originally Posted by dougmc View Post
    Having everything being charged through mini-USB ports is convenient, but it also means that everything needs to be bumped up or down to 5 volts, which introduces inefficiencies. But for the most part, the convenience makes it worthwhile.
    I'm not sure what you are getting at here. The phone/tablet uses USB. I suppose the issue is whether USB is "good enough" for lights.
    Last edited by njkayaker; 11-07-13 at 05:01 PM.

  11. #11
    Vegan on a bicycle smasha's Avatar
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    if i had the money i'd buy a few of these - http://www.voltaicsystems.com/fuse4w.shtml

    instead, i've got a couple of these - http://dx.com/p/miniisw-yg050-5w-por...n-black-206560

    and these - http://dx.com/p/eser-010-4400mah-rep...te-grey-208832

    based on my measurements, that DX panel puts out ≈4W in direct sunlight, in wellington NZ. that's about 800mA while struggling to hold 5V (often dropping to ≈4.8V under heavy load).

    for commuting, this is a good setup... when the sun is out . i leave the panels at home, sometimes charging devices directly, usually charging the battery packs. i can keep my lights (1), phone (2), and video cameras (3) all charged up with power to spare... of course i rarely ride more than an hour per day, often less.

    if i were doing any multi-day tours, i'd probably pony-up for the fuse-4w. the DX stuff is working great, but it's not designed to handle weather or bumpy roads... the voltiac stuff is designed for that.

    1- red-zone-8, white-zone-10, 18650 T6, and a hotshot
    2- a dumb phone that often DISCHARGES when i connect it directly to the panel. it charges fine from the battery packs.
    3- 3x gopro heros. sometimes more.
    "When I see an adult on a bicycle, I do not despair for the future of the human race." - H.G. Wells

  12. #12
    Rod & Judy gracehowler's Avatar
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    There are some great articles in crazy guy under the heading of "digital", especially wayne estes, good reading.
    http://www.crazyguyonabike.com/doc/c...octype=article
    R
    btw, I'd like to know your negative thoughts on dynohubs?

  13. #13
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    Quote Originally Posted by smasha View Post
    if i had the money i'd buy a few of these - http://www.voltaicsystems.com/fuse4w.shtml
    I like the suntactics sCharger 5 better. It puts outs a true 5W, it's rugged, only weighs 8 ounces, and costs about the same.

  14. #14
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    Quote Originally Posted by gracehowler View Post
    There are some great articles in crazy guy under the heading of "digital", especially wayne estes, good reading.
    http://www.crazyguyonabike.com/doc/c...octype=article
    R
    btw, I'd like to know your negative thoughts on dynohubs?
    Dynohubs are expensive, the lights are expensive, and they are of limited use to me on tour. The reason is that I like to tour in the mountains, and I'm relatively slow going uphill. I've gone entire days losing charge in my phone. For touring in Florida or Holland, fine, but not for the in the Rockies, at least not for me.

    The alternative for me is taking a battery or two. You can get an Anker 15,000 for less than $50 on amazon (minus 10% for black friday deal, check their site). It weights 11 oz and can charge up an iPhone 5 nearly 7 times. Coupled with a lightweight solar panel, I have a much more reliable way to keep the phone charged up.

    One last remark is that I have the Schmidt Son28, which is supposed to be the most efficient. However, it does have a vibration, which always makes me worry that I'm losing efficiency. It's ludicrous, but it bugs me.

  15. #15
    Vegan on a bicycle smasha's Avatar
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    Quote Originally Posted by northerntier View Post
    I like the suntactics sCharger 5 better. It puts outs a true 5W, it's rugged, only weighs 8 ounces, and costs about the same.
    i'd be concerned that the hinge would fail. the extra weight of the fuse-4W seems to be what makes it more rugged. also, it comes with a well designed and well made battery pack. one of the things i learned while dicking around with solar charging stuff from DX is that not all battery packs work well with solar panels. sure, when the sun is bright, they're fine... but when there's intermittent cloud cover, or if you want to leave it plugged in when you go to bed... that's when some battery packs will discharge through the panel.

    that said... the suntactics one may be better for weight-weenies.
    "When I see an adult on a bicycle, I do not despair for the future of the human race." - H.G. Wells

  16. #16
    Rod & Judy gracehowler's Avatar
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    Quote Originally Posted by northerntier View Post
    The alternative for me is taking a battery or two.
    I am about convinced the battery idea is the best, at least for touring in USA, the most we have had to ride is three days without edison.
    R

  17. #17
    Senior Member Road Fan's Avatar
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    Quote Originally Posted by fietsbob View Post
    just remember the solder bridges to connect the elements together take up surface area
    and generate no power.
    so 100% efficient .. is as achievable as honest politics or Just-Wars.
    Good point, but I'm not sure that's the answer to the 14 versus 10 watts issue. The total solar array area can capture a certain amount of solar energy, but only the active area of silicon collects energy that can produce electricity. That lost area is due to interconnects, bus bars, mechanical support, and the fact that solar cell itself contains interconnects.

    I assume that by "100% efficient" you meant "maximum efficiency," since not too many solar cells are better than 20% efficient, and most are much worse.

    Beyond that the major effect limiting output is the angle of incidence of solar energy, or cosine loss. There are actually a bunch more factors in the efficiency of a solar array, so many that we really don't know what the manufacturer was really talking about in 14 w advertising number and the 5v/2a cases. The V and I specs I used back when I designed PV power systems were the open-circuit voltage and the short-circuit current. And the power that they defined is not achievable in a real solar array.

    Bottom line: it's complicated.

    I think a bigger issue is, does the OP intend to run a dyno light? If so he needs to bypass the rectifier that is in an LED dyno light, if 5 volts is the correct internal voltage for the LEDs. If they have current limiting that typically requires additional voltage drop.

  18. #18
    coprolite fietsbob's Avatar
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    The fact that people cannot leave the electronics at home and just ride the bike ,
    has a number of companies using the power output of the Dyno-hub
    to trickle charge with a USB compatible output.
    The Plug, from Tout Terrain is a new threadless top cap, AXA and B&M integrate it inside a headlight

    B&M also make a black box you can strap on, maybe rewire it to be in a handlebar Bag,
    so you can take it off the bike, when you park the Bike. .

  19. #19
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    Quote Originally Posted by Road Fan View Post

    I think a bigger issue is, does the OP intend to run a dyno light?
    No, I just want to keep iphone (on a lot for GPS) and ipad charged.

    I do have a Plug II+, and still have the problems in hills I mentioned above.

  20. #20
    Rod & Judy gracehowler's Avatar
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    Do you know how many watts it takes to keep an iphone on for gps? I'll bet more than we are thinking, hence the dyno and hill problems.
    R

  21. #21
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    Quote Originally Posted by gracehowler View Post
    Do you know how many watts it takes to keep an iphone on for gps? I'll bet more than we are thinking, hence the dyno and hill problems.
    R
    No worries on the flat, but the iphone is finnicky about it's power supply, and will not charge consistently at less than 8-10 mph. On a long/steep hill, I might be doing less than 4!

  22. #22
    Senior Member dougmc's Avatar
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    Quote Originally Posted by gracehowler View Post
    Do you know how many watts it takes to keep an iphone on for gps?
    Well, a 500 mA charger works out to 2.5 watts, and it will keep the iPhone charging even while it's busy running a cpu-hungry app -- and most gps apps are not particularly cpu-hungry. So the power consumption will be less than 3 watts, and the phone will actually be charging at that point rather than having its battery level staying the same.

    That said, your dyno is going to need some speed to achieve the rated output -- it may not charge going up hill, but the again, as long as you're going at a reasonable clip at least half the time the phone will probably remain charged. You might have problems if you're going up a mountain all day, however.

    Personally, if power is a concern, I'd suggest a basic cyclocomputer -- it'll last months on a small battery. Save the GPS for when you're actually lost or need to make a decision about where to go. Also, a dedicated GPS (like Garmin Edge or handheld model -- not a car model) will have better battery life than a phone running a GPS app.

  23. #23
    Rod & Judy gracehowler's Avatar
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    We personally use a garmin for bicycling and can squeeze two days out of the battery. I once tried to use my android for a " find my way" through Portland drive and it was dead in less than two hours. I have heard it is much harder to charge the apple products.
    R

  24. #24
    Vegan on a bicycle smasha's Avatar
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    i should mention.... there is one advantage to going with more power than you think you need. solar panels produce max power under "ideal conditions". bright sun, no clouds, no haze, no fog, panel is directly perpendicular to the sunlight, etc.

    knock one or more of those factors out of whack, and your panel is now producing less than max power. on a touring bike (as on a sailboat, or even an unattended camp-site) it's not possible to keep the panel directly perpendicular to the sunlight, just to point out one factor that affects output power.

    so... let's say you need 5W. if you have a 5W panel that's only producing 50% power, you get 2.5W. if you have a 10W panel producing 50% power, you get 5W.

    something to think about.
    Last edited by smasha; 12-01-13 at 06:09 AM.
    "When I see an adult on a bicycle, I do not despair for the future of the human race." - H.G. Wells

  25. #25
    Senior Member Road Fan's Avatar
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    Quote Originally Posted by gracehowler View Post
    Do you know how many watts it takes to keep an iphone on for gps? I'll bet more than we are thinking, hence the dyno and hill problems.
    R
    Better questions are, what are the minimum and maximum voltages an iPhone needs to be fed for good charging? Minimum is important because you don't want the charging function to turn off and surprising you with an uncharged phone. Maximum is important because too much voltage can damage electronics - your devices may or may not contain internal protection. Also is it sensitive to unintended reverse polarity?

    Then there's current: with the voltage in the range implied by the first two questions, how much current is needed to charge the battery in a reasonable period of time and not compromise battery life? These are actually minimum and maximum questions as well.

    Answer these and you can tell if it's adequate to connect up any given battery or solar array, or if you should have a power conditioner of some sort.

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