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  1. #51
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    I just want to point out something for those that were mentioning the rate of reduction in capacity for li-ion cells. If you look here you can see that if lithium ion cells are stored at 40% charge and stored at 0C (or basically close to refrigerated temps) you can see as little as 2% reduction in capacity over a year. This is of course ignoring the reduction in capacity from charge cycles but it should take a couple hundred of those before you really have to start worrying about significant losses.

    So, use your battery then throw in in the fridge till you charge up for next time and you'll be in good shape. If you think you totally drained it then charge it for just a little while then throw in the fridge. Avoid moisture damage by single or double ziplock bagging.

    20% reduction in charge seems to only come from storing fully charged at room temps so just don't do that! Also, leaving li-ion cells in a car on a sunny day can do a lot of damage.

  2. #52
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    Can you plasti-dip the stock magicshine battery to make it waterproof? It rains a ton here and someone mentioned frying theirs in the rain on one of the threads.
    "It looks flexy"

  3. #53
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    Quote Originally Posted by gticlay
    Can you plasti-dip the stock magicshine battery to make it waterproof? It rains a ton here and someone mentioned frying theirs in the rain on one of the threads.
    Yes: Plastic dip battery waterproofing (for MagicShine, etc)

  4. #54
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    Maybe a dumb question, but if I bought those red protected 3000mah cells, can I just solder them into a pack since they are individually protected?
    "It looks flexy"

  5. #55
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    Quote Originally Posted by gticlay
    Maybe a dumb question, but if I bought those red protected 3000mah cells, can I just solder them into a pack since they are individually protected?

    You can solder them into a pack but then you would not be able to charge them up

    better to get one of the holders around on here and put a cable on it to suit the MS light.
    still recomend to keep the beggers dry though .

  6. #56
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    Quote Originally Posted by troutie-mtb
    You can solder them into a pack but then you would not be able to charge them up

    better to get one of the holders around on here and put a cable on it to suit the MS light.
    still recomend to keep the beggers dry though .
    Huh? Wouldn't you just plug them into the Magicshine charger? Those are soldered into a pack.
    "It looks flexy"

  7. #57
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    Quote Originally Posted by gticlay
    Huh? Wouldn't you just plug them into the Magicshine charger? Those are soldered into a pack.

    Yes you could but if you used protected cells each cell has a circuit on it that would dislike the 8.4 volts the MX charger would be trying to put into the pack .

    you need to use unprotected cells and put the correct protection circuit on the whole pack .

  8. #58
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    Quote Originally Posted by troutie-mtb
    Yes you could but if you used protected cells each cell has a circuit on it that would dislike the 8.4 volts the MX charger would be trying to put into the pack .

    you need to use unprotected cells and put the correct protection circuit on the whole pack .
    Um, not quite. Since two 18650 cells will be wired in series (plus N pairs in parallel to that), each cell will "see" only half voltage of the charger's output. So, protection circuit of each cell will be quite happy with the input and will have no reason to interfere in the charging cycle until the voltage of that individual cell will reach the protection circuit's upper voltage threshold (but, by that time the charger itself will probably already "shut itself off" since the two-cells-in-series pair will hopefully reach charger's upper voltage threshold before that).

    In short - you can safely use MS charger to charge "home-made" packs of protected 18650 cells, as long as the cells are wired in 2SnP configuration.

  9. #59
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    Quote Originally Posted by ortelius
    Um, not quite. Since two 18650 cells will be wired in series (plus N pairs in parallel to that), each cell will "see" only half voltage of the charger's output. So, protection circuit of each cell will be quite happy with the input and will have no reason to interfere in the charging cycle until the voltage of that individual cell will reach the protection circuit's upper voltage threshold (but, by that time the charger itself will probably already "shut itself off" since the two-cells-in-series pair will hopefully reach charger's upper voltage threshold before that).

    In short - you can safely use MS charger to charge "home-made" packs of protected 18650 cells, as long as the cells are wired in 2SnP configuration.
    Technically true, but there are some pitfalls in practice.

    The biggest potential problem is all the Trustfire protected cells I've tested, have a very low upper protection limit of 4.15V. Since this is below the typical charger voltage regulation of 4.2V per cell, the batteries tend to shut down as soon as the constant voltage stage of the charge cycle starts. That means they'll only reach 60-70% of full charge. If folks have other brands of protected cells and have tested them, I'd really like to hear the upper and lower limits on the protection PCB.

    The other problem is how well the cells are matched. Since they are loose cells, if you mix and match different ones you'll end up with the protection PCB on the weaker cell ending the charge very early because it's voltage will go up really quickly compared to the stronger cell during the current limited stage of the charge. Even if you keep the same set of cells together, you may run into balance problems because the cells aren't likely from the same manufacturer batch and date.

  10. #60
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    Thanks for the corrections folks
    so what if it was only a 2 s cell pack

  11. #61
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    So the magicshine runs off of 2x2 packs. I don't know anything about current battery technology, but matched packs and a full discharge with an individual cell discharger was the bomb when I raced for an R/C Car factory team. 7 cell modified with a 13x2 Reedy motor baby!
    Last edited by gticlay; 01-04-2010 at 11:14 PM.
    "It looks flexy"

  12. #62
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    Quote Originally Posted by gticlay
    So the magicshine runs off of 2x2 packs. I don't know anything about current battery technology, but matched packs and a full discharge with an individual cell discharger was the bomb when I raced for an R/C Car factory team. 7 cell modified with a 13x2 Reedy motor baby!
    Yes, it's a 2x2 pack.

    Li-ion batteries have very different characteristics than Nicad or Nimh batteries. Running them all way down is about the worst thing you can do to them. They will last far longer if only partially discharged and charged. They also have their max capacity when brand new and lose a tiny bit of capacity with every cycle. So cycling them will never increase capacity, only reduce it.

    Here's an interesting piece of info. If your light has much longer runtime than you need for typical rides, then charge your li-ion packs up to 3.9 volts / cell instead of the typical 4.2 volts / cell. They'll only have about 75% of the stated capacity of the battery available, but you'll get more than 2x more cycles from the battery. If you do that and store the batteries in the fridge at 40% charge whenever they aren't being used for long periods. They'll last virtually forever. You can still charge them to 4.2 volts / cell on the occasions when you need the full runtime,.

    Unfortunately, you need a charger that'll let you control the voltage limits to do that. I've never really found what I consider a really good flexible li-ion charger. I charge mine off a nice variable power supply where I can set the voltage and current limits. But, you should only do that if you're meticulous about setting it correctly every time. I've come so close to building my own li-ion charger so many times.... I just need to stop building new lights and then I'd have time to build some nice chargers.

  13. #63
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    Quote Originally Posted by troutie-mtb
    Thanks for the corrections folks
    so what if it was only a 2 s cell pack
    Like most things, there are lots of competing tradeoffs. Ironically, if you do build packs out of individually protected cells, you'll probably have the best luck with 2s2p or 2s3p configurations. That's because the parallel banks of cells will more or less average out and be less likely to be significantly weaker or stronger than the other parallel bank. Where as a 2 cell 2s pack will be hit or miss just based on how well the 2 cells happen to be matched. You can of course make it work well if you profile the cells and make sure you use well matched ones together.

    Because of this, it even matters to some extent the position of each cell in the pack if you're keeping a set of cells together. Lets say you have a set of 4 cells and 2 of them are a little weaker and 2 a little stronger. if you have a weak and strong cell together in each parallel string the pack will work well. If the 2 weak ones end up together in a bank the pack won't work as well.

    when you get into deeper parallel configuration, 4p and more, you start to run into bigger issues with how evenly the current divides between the parallel cells.

    when you get into longer serial configuration, 3s and more, you start to run into bigger issues with the voltage balance between the cells.

    How much of an issue all of this becomes depends a lot on how hard you're pushing the packs. If you only really need a moderate amount of the pack's capacity, say 65%, then you're a lot less likely to run into issues. Because most of these issue are pronounced at the limits. But, in general, I think if you're using battery holders you'll probably have better results if you charge the cells individually and keep similar cells together. By similar I mean same age and same number of cycles.

  14. #64
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    The battery for my magicshine stopped working about a week after a ride where it got wet (no other rides after). It worked for about a week after the ride and then just cut out.
    The battery connections were all corroded, so i've taken them all off and now have the batteries all separate.
    Dont know if i should have tried this, but i got a wire from each end of each battery and touched the wire to the lighthead plug connections, nothing happens (with any of the batteries)
    Should the unit light up when i do this?
    Where shall i go from here with the battery pack in pieces....?

  15. #65
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    Joe,
    You can post it to me to look over if you want, please make sure it is safely wrapped up before posting though, if all else fails I should be able to build you a compatible battery for it.

    Smudge

  16. #66
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    Thanks smudgemtb, thats a good offer. I'd rather have a go at fixing it myself (if anyone can guide me in the right direction) first of all. If that dosnt work, i'll send you a PM.
    Cheers
    Joe

  17. #67
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    Quote Originally Posted by joehspicer@msn.com
    The battery for my magicshine stopped working about a week after a ride where it got wet (no other rides after). It worked for about a week after the ride and then just cut out.
    The battery connections were all corroded, so i've taken them all off and now have the batteries all separate.
    Dont know if i should have tried this, but i got a wire from each end of each battery and touched the wire to the lighthead plug connections, nothing happens (with any of the batteries)
    Should the unit light up when i do this?
    Where shall i go from here with the battery pack in pieces....?
    If you were connecting a single cell to the magicshine light, then no it will not light up. The voltage of a single cell is below the minimum voltage for the driver. The normal arrangement for this battery is 2 parallel strings of 2 cells in series (2s2p). That gives a nominal pack voltage of 7.4 volts. The driver in the magicshine stops functioning around 5 volts.

    I'm not quite sure what you mean by "I've taken them all off". If you mean you've disconnect the spot welds for the connecting straps, then it's going to be hard to safely reassemble the pack. Unless you happen to have a battery spot welder. Soldering to li-ion cells is not really a safe thing to do. Some good picture of the state of the pieces would be a good way of providing the info that would be needed for folks to offer advice.

  18. #68
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    Quote Originally Posted by joehspicer@msn.com
    Where shall i go from here with the battery pack in pieces....?
    Depending on your soldering skills you could go the holder route. This lets you use individual cells as opposed to a pack, which is nice as you can replace cells as they wear out ...which they will given just time. An option at least

    Read more here >>

    Good luck ~Chris

  19. #69
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    this one with the switch , is a 8 cell pack, build myself.
    if you want one , PM me.

    there is also one without the switch, taller one, where you can use 2 of you existing ms packs, just put them in, done.

    also working on a lupine battery bottle, improved version, with higher capacity,
    and faster charge time. PM if interested.

    working on batteries and LED lights.
    from mtb to military use
    LED's from mtb , street commuter to police/military use. 500 to 3500 lumen.


    Quote Originally Posted by HEY HEY ITS HENDO
    ----
    DIY battery + light working on it

  20. #70
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    Thanks for the help guys, its coming in pretty usefull.
    I've borrowed a voltmeter, none of the batteries are giving a reading of more than 0.15v, does this mean the batteries just need charging, or theyre ruined?
    And the only charger i have that they'll fit in is designed for NiMH and NiCd batteries, will this be ok to use?.... whats the difference between this charger and Li-ion chargers?

  21. #71
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    If they're really at 0.15v then they're ruined.

    Nicad and Nimh battery chargers are constant current chargers. Li-ion charger are primarily constant voltage along with a current limit for the first stage of the charge. Putting a li-ion battery in a nicad / nimh charger will not work and is very dangerous. It could very well result in a fire.

  22. #72
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    use a car charger, it does charge it really fast,...

    if you got a MS battery, you should have the li-ion charger,...
    so why would you use a nicd or nimh charger ??

    wonder why, dell is charging an arm and leg for new batteries,...
    why the mac has in sealed integrated one,...
    why they start hussling, everybody on the airport,... how much lithium you got,...
    you are only allowed, oh, couple grams, 1/2 ounce tops,... gee



    Quote Originally Posted by joehspicer@msn.com
    Thanks for the help guys, its coming in pretty usefull.
    I've borrowed a voltmeter, none of the batteries are giving a reading of more than 0.15v, does this mean the batteries just need charging, or theyre ruined?
    And the only charger i have that they'll fit in is designed for NiMH and NiCd batteries, will this be ok to use?.... whats the difference between this charger and Li-ion chargers?
    ----
    DIY battery + light working on it

  23. #73
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    btw guys DX are now selling replacement battery packs (and a case) for these $30.

    I was going to build my own $20 for the 4 cells I wanted, extra $10 for the connector, charging curcuit and case... worth it imo. I'm now wondering about a 8 cell pack instead (because buying one is just too easy )

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