AA battery pack for original Magicshine- Mtbr.com
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  1. #1
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    AA battery pack for original Magicshine

    I have one of the original Magicshine lights and would like build a AA based battery pack for it. I'd like something that requires 4 AA if possible.

    I have no idea how to figure runtime/etc. Anyone?

    Can anyone point me in the right direction? Suggestions?

    Thanks!
    www.thepathbikeshop.com

  2. #2
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    you'd need 6 (7.2V) or 7 (8.4V) NiMh AAs in series and the best capacity you're likely to get would be ~2600mAh. For alkalines, 5 AAs (7.5V) would probably be fine. Is this for adventure racing/ long distance touring?

  3. #3
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    Buy a 6x AA holder. Use 6 2000 to 2500 mAh rechargable AA's.

    Should give around 2 hours run time.

    You could also wire 2 3x C or D cell holders in series and double or triple your run time. personally I would just get 2 6x AA holders if you need those sort of run times.

    Holders can be found on ebay, or batteryspace.com

    You will need to get another connector or cut the one off the old battery pack.

    Radio shack should have a matching connector.

    In some thread around here is the mm measurement of the male and female magic shine plugs.

    Good luck.

  4. #4
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    Quote Originally Posted by mattthemuppet View Post
    Is this for adventure racing/ long distance touring?
    Sort of....multi-day bikepacking/racing events where recharging battery packs is not an option.

    That being said it sounds like I wouldn't be able to get anywhere near the runtime per battery that I'd need to get to make it a viable option.

    BB
    www.thepathbikeshop.com

  5. #5
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    hmm, tricky. I know that there were a few similar threads and someone suggested a small solar panel and DC converter, but I don't know how viable that is. One option would be to get a couple of spare li-ion packs and just use the AA pack as an emergency power source. More weight to carry around though..

  6. #6
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    Would it be to expensive with a hub dynamo wheel and a good purpose built light?
    Take a look at http://forums.mtbr.com/7809561-post8.html
    Ktronik: dynamo powered triple XP-G for MTB use

  7. #7
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    I set up some 6AA packs for my friends. 2x3AA for the L-Flex lights, 1x6AA for the L333, which is similar to your Magicshine.

    This was as a backup after their lithium rechargeable packs were used up, in a 6-day adventure race.

  8. #8
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    Will you have access to a car?

    If so, you can use hobby type Lipo or LifePO4 packs that can be charged off a R/C charger. These chargers usually have power connectors that connect to the battery terminals.

    If you use Lipo packs, pick the hard case packs so you have a little more protection. The LiFePO4 packs are safer but weigh more.

  9. #9
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    Quote Originally Posted by donkey View Post

    That being said it sounds like I wouldn't be able to get anywhere near the runtime per battery that I'd need to get to make it a viable option.

    BB
    How much total runtime do you need? The posts so far have been about using rechargeable AA batteries. If you're thinking about Alkaline AA batteries that you can buy along the route, that's kinda a different ballgame. Give some more info about what you need in terms of runtime / brightness and I'm sure we can offers some good options.

  10. #10
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    Quote Originally Posted by MtbMacgyver View Post
    How much total runtime do you need? The posts so far have been about using rechargeable AA batteries. If you're thinking about Alkaline AA batteries that you can buy along the route, that's kinda a different ballgame. Give some more info about what you need in terms of runtime / brightness and I'm sure we can offers some good options.
    The basic idea is to use non-rechargeable AA batteries(likely disposable lithiums) and get as much run time and light from them as possible.....in sub-freezing temps.

    My current setup is a Princeton Tec Fuel headlamp and a Fenix E21 on the bike. This setup gets fairly good runtime and is enough light for this particular application.

    If I could replace the Fenix with a Magicshine head unit/AA battery pack and get a similar amount of light to the Fenix but longer runtimes i'd be thrilled.

    Anything rechargeable is a non-starter for me......the light needs to run on disposable AA batteries as that's all I'll have access to.

    Thanks!

    BB
    www.thepathbikeshop.com

  11. #11
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    Donkey, after re-reading this thread I can see that my previous post doesn't really address your situation. Sorry.

    Using disposable lithium batteries you'll need:

    A. The most efficient LED to give you the most light with the longest runtime = Cree XML LED

    B. Company that specializes in AA lights for adventure racers, commuters etc. = DiNotte Lighting

    A + B = DiNotte XML-1 AA battery light

    MTBR review on the DiNotte XML-1

    DiNotte Lighting FAQ on AA

    I don't own one of their lights, so I'm a fairly neutral party. All I've heard is that they produce a high quality product with excellent support. They've been around since 2005 and I think you should at least consider this option.

  12. #12
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    One thing of note is that Dinotte under-drives their XM-L so it doesn't throw a ton of light on max.
    I made up AA holders for adventure racing that were 2 sets of 4lithium AAs in parallel. I upgraded the wiring a bit too, and made a custom plastic bag to fit over them out of vacuum-seal material.
    They ran a 7.2v light pretty well, and will probably run your Magicshine just fine.
    You can also upgrade your Magicshine to an XML if you're handy.

  13. #13
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    Quote Originally Posted by donkey View Post
    If I could replace the Fenix with a Magicshine head unit/AA battery pack and get a similar amount of light to the Fenix but longer runtimes i'd be thrilled.

    Anything rechargeable is a non-starter for me......the light needs to run on disposable AA batteries as that's all I'll have access to.
    The Fenix E21 puts out 150 lumens on high with about 2 hour runtime and 50 lumen on low with an 11 hour runtime. I would guess you're mostly using the Fenix on low. The Princeton Tec Fuel only puts out 43 lumens on high, and much less on medium and low.

    You won't get anywhere close to those runtimes with a Magicshine even on the low settings because it's putting out more light and as a result using more power. On low the magicshine is putting out 200-250 lumens. The magicshine driver also isn't particularly efficient.

    Here's a very interesting set of graphs from the Energizer technical data sheets for Alkaline and Lithium AA cells



    Since the magicshine draws 2600mW on low, which is about 500mw per battery for a 6 cell pack, the graphs tells you you'll get about 1.5 hours of runtime from a 6 cell Lithium AA pack. If you can't find Lithium cells along the route and have to use normal Alkaline cells, you'll get about 30 minutes at 21c and 10-15 minutes at freezing.

    So all in all, not a very workable solution.


    What is probably a better solution, would be a light based on the TaskLED programmable drivers. There are folks that hang out on the board that sell custom built lights that use these drivers. This is a better solution because these drivers can be programmed for low brightness levels and the drivers are very efficient at low levels. Even if you're not going to recharge them along the route, you may still want to consider a rechargeable li-ion based battery pack. That's because you get really high energy density with this type of pack. To give you an example, if I set my DIY lights that use the TaskLED drivers to a 100 lumen output level, they run for 80 hours off a 4 cell li-ion pack. If you take 2 packs, you're talking almost 2 weeks worth of nighttime light and the quality of the illumination will be much better than your current setup.

    If you're not going that route, a dynamo setup is probably a better choice as others have suggested. But you'll still have to take one other lights just in case the dynamo fails.

  14. #14
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    Great graph you found MtbMacgyver. I never knew the cold affected regular cells so badly.

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