USB rechargable Magicshine compatible batter pack. Does something like this exist?- Mtbr.com
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  1. #1
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    USB rechargable Magicshine compatible batter pack. Does something like this exist?

    Context: I've got a dyno hub on my bike with a USB output. The original plan was to use the Expilion 850 USB light on Medium setting and just use the dyno hub to charge it. That light is supposed to go 3 hours at ~300 lumens and 9 hours at ~100 lumens. I'm finding real world to be more like 1.5 hours @ 300 and 4 hours at 100. That's not going to cut it, as sometimes at night, I'll have to go 3-4 hours straight with climbing SUPER slowly (hub only charges at > 4mph)

    In the past I've used a 4 18650 battery pack with my "900 Lumen" Magicshine. On the low setting of ~200 lumens, that sucker goes 12-14 hours with that battery.

    What I would LOVE is a double 18650 pack that I could charge off of USB somehow, but still be able to get power out with the magicshine plug. This should allow me to get let's say 5-6 hours on low, which would give me enough safety margin.

    Does such a thing exist? Any other ideas? (I'm trying to avoid the $300 dyno hub light here)

  2. #2
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    Just buy high capacity battery pack and you are done. 6 cell pack should be sufficient, maybe even 4 cell pack - you need to do some calculation. No need for dynamo there. See threads:
    http://forums.mtbr.com/lights-night-...nd-997165.html
    http://forums.mtbr.com/lights-night-...ce-995303.html

    Any other way would have some looses involved as you would need step up converter from USB 5V to 8.4V and you need CC/CV regulation to charge Li-Ion packs. Not good to do it with variable current.

  3. #3
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    Quote Originally Posted by trhoppe View Post
    Does such a thing exist? Any other ideas? (I'm trying to avoid the $300 dyno hub light here)
    Dyno lights are much cheaper than that. This is what I use currently, about 60 US$
    Busch & Müller Lumotec IQ Cyo 2014

  4. #4
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    I need this to last through 5 nights of night riding with no re-charge other than through my dyno, so no go on the battery pack

    As far as the other dyno lights a) they don't have a stand lite setup and b) they don't hold up to the colorado trail

    I DID find this on eBay though: Amazon.com: Urparcel 1200LM 3 Modes CREE 5V XML-T6 USB LED Headlamp Headlight Bike Bicycle Light: Sports & Outdoors

    Which is a Cree XML T6 LED light, but powered off of USB. I think this is exactly what I need/want. This let's me use a regular USB powered cache battery to power my light. Now the question is, how long will it last For $9 and free shipping/return, worth a try

  5. #5
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    You did not said that in your first post. I would be thinking diferently then. What are you doing during day time? You could charge battery pack with solar pannel. Or you might think of using USB power pack (with solar pannel attached) which can be charged either by dynamo or by sun light. Of course efficieny is not very high.

    The light you have linked is no way of 1200Lm even 600Lm is optimistic. Since you won't be able to drive light at higher curents there is good chance it will last long enough. Shurely I would open it and inspect internals. If you are in doubts post internals pictures here.

  6. #6
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    Cell phone battery chargers. solar panel ones are available, plus you can charge them during the day with the dyno. don't get the wimpy little ones tough. Their circuits will shut down pretty quick when you first put a light on them. Get a good one.
    "a hundred travel books isn't worth one real trip"

  7. #7
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    One solution here is use a USB cache battery with "pass through" capability, so it will charge up while powering devices. You'll need a front light with a low power mode if you're spending all night climbing hills.
    Personally I'd still go with a dedicated Dynamo light for night use.

    Some ideas here:
    kLite.com.au Dynamo Lighting Systems

  8. #8
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    A USB powered light has low efficiency. The batteries in the USB power bank run through a voltage conversion circuit to ether boost to 5V or drop to 5V depending on whether they are series or parallel configured. Then the light you linked needs about 3.3V at the LED so the 5V from the USB gets dropped to 3.3V. At each stage of power conversion you will lose at least 10% of your power and likely more.

    znomit's advice to go with a dyno light is much more efficient.
    GoPro adapters for bike lights http://www.pacifier.com/~kevinb/index.html

  9. #9
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    Gloworm now has a self contained light that you can run while it's being charged by your dyno hub. 900 lumens is rated to 2.5 hours, so at 400 lumens you should get over 5 hours on the battery alone. If you can climb with 200 lumens I would expect it would give you tons of cushion. Seems like it might work well for you. Costs $135, not super cheap but not too crazy.

    There is a thread about it somewhere in the other Lighting forum here as well.

    Gloworm CX Urban and Trail – Action-LED-Lights

  10. #10
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    That Gloworm is a pretty badass setup for $135 I think.

    In the end I ended up taking all the advice of everyone before me

    I bought the Klite Backpacker Pro dyno light and also a Black Diamond Revolt headlamp as emergency backup. Done and Done.

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