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  1. #1
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    NiMH battery storage question

    I had always thought it was best to store the batteries with a full charge. I had a battery rebuilt this weekend by a guy at Batteries Plus and he told me they should be discharged before storing. He explained why, and it seemed to make sense. I did get an "incomplete" in physics of electricity in college, so I am looking for a few more opinions.
    What should be done and why???
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  2. #2
    mtbr member
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    I wouldn't think it'd matter hugely. Self dischage means the cell will be flat after a while anyway.

  3. #3
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    Quote Originally Posted by teamdicky
    ...he told me they should be discharged before storing. He explained why, and it seemed to make sense...
    I'd like to hear his reasoning.

    I've always stored NiMH batteries fully charged, per many manufacturer's instructions and FAQs. I don't recall the reasoning behind it.
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  4. #4
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    Crap

    Stright from L & M's website:

    How should I store my NiMH, or Li-ion Batteries?
    You should always store your batteries in a fully charged state. Keep them in a cool dry place and every 3-4 month fully recharge them to maintain the best over-all life.
    I am gonna keep looking for more info.

    Niterider basically said the same thing in thier manual.

    Maybe the guy at BP was alittle off on his info. He did tell me that the moon was made of cheese.
    Last edited by teamdicky; 09-06-2005 at 08:53 AM.
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  5. #5
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    Quote Originally Posted by teamdicky
    I did get an "incomplete" in physics of electricity in college, ..
    As far as batteries are concerned, no one seems to know. We need some peeps who got their PhD in Battery chemistry to give the difinitive answer. However, I think the reason no one seems to know, is the chemistry is complex and almost every possible thing you do with a battery has an influence on everything else.

    However, my understanding is you can store both NiCad and NiMH charged or uncharged, but when you store batteries uncharged, the chemistry begins to deactivate reducing the performance of the battery. When you store it charged, you reduce this time, but eventually the batteries discharge anyway. So the real answer according to some manufacturers is to store NiMH however you want, then when you use them, cycle the charge a few times to restore them to normal capacity. NiCads don't necessarily recover like NiMH when doing this. Thus, NiCads need to be periodically charged (once a year).

  6. #6
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    Quote Originally Posted by teamdicky
    ...he did tell me that the moon was made of cheese.
    Well, I guess they were right after all: http://moon.google.com/

    (Zoom in to max magnification.)
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  7. #7
    local trails rider
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    Here's some guys who use their batteries hard (fast charge, fast discharge)

    http://www.rcgroups.com/forums/showt...=nimh+storage+

  8. #8
    the wrench
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    ni-cad batteries are the only batteries that should be stored flat. nimh and li-on bateries should be stored fully charged and topped up before use. nimh batteries should also be fully cycles a few times a year as well. i could go into details of why this is or better yet i will give you a link explaining everything you need to know about batteries and battery charging etc.

    www.buchmann.ca has lots of info on batteries and reasons why things are done a certain way and dont worry the author has made it an easy read for the non tech types.
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  9. #9
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    I come from a R/C racing background where batteries are everything. I stored my packs completely discharged. I used a voltage dropping discharge tray to discharge each cell individually to a certain voltage. It helps the power output and capacity. It was more important with NiCads than with NiMH, but still helped.

    However, for something like the batteries powering a light or something, it shouldn't matter. The whole theory behind NiMH is that it doesn't develop a memory like NiCads do. I would just store them charged, that way when you need one you don't have to charge it. The peak voltage and capacity may suffer ever so slightly, but not enough where you would notice.

  10. #10
    Gone riding
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    No matter how you store them, I would still cycle the cells every 2-3 months just to give them some use. I've heard both sides to the charged vs. discharged dispute, and they both have good and bad points.....still haven't made up my mind.

    Having said that, I personally store my packs charged, and cycled them about once a month. Seem to be holding up fine so far.

    Cheers, Dave

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