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Thread: NIMH question

  1. #1

    Default NIMH question

    Hi...just got a panasonic AA dn AAA charger with 2100 mah AAs and 700 mah AAAs...I need to get some more batteries...do I need to get Pansonic or will any NIMH do? Also, will 2000 AA and 700 AAA mah be just as good (since they are relatively cheap on the web at 19.95 for 24 from batteryspace.com)...thanks

    Oh, one more thing....storage wise, if I charge a set of back-up batteries, how long do they last unused? I heard NIMH lose power daily.....thanks thanks

  2. #2

    Default Re: NIMH question

    .

  3. #3

    Default Re: NIMH question

    thank you...I will order the batteryspace cells tomorrow....

  4. #4
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    Default Re: NIMH question

    Hello FlameOn,

    The self discharge rate of NiMH batteries is suppose to be around 1% of the remaining charge per day.

    At the end of 70 days they are down 50% and after 120 days they have 30% of the original charge. At the end of a year (365 days) they only have 2.5% of the charge left.

    I believe that new cells discharge at a lower rate. I have measured a 30% loss in 60 days in my TigerLights.

    As DrJ pointed out, you should be able to use any brand of NiMH batteries in your charger.

    Tom

  5. #5
    Flashaholic*
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    Default Re: NIMH question

    If a low self-discharge is important to you, you can try Ni-Cd. I believe they have a lower self-discharge rate than Ni-Mh.

  6. #6

    Default Re: NIMH question

    I'm basically using them in my wireless keyboard, mouse, remote controls and a few small AA flashlights so I should be okay...thanks

  7. #7
    Flashaholic Wildcat's Avatar
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    Default Re: NIMH question

    I have a question on this subject. I have seen some AA's at wallyworld with charger that are supposed to recharge in 15 minutes. I have a chager that takes 15 hours. Which is better and is there a happy medium for charge time and output?

  8. #8

    Default Re: NIMH question

    I think the 15 minute chargers only take 15 minute batteries and I wanted to buy more cheaply in bulk so I went with the panasonic regular charger and order a 24 pack of aa and aaas for 19.95 with free shipping from batterspace,com...my charger takes a few hours but with back-ups, I don't see the rush....

    now regarding back-ups and the discharge rate...if I have a bunch of spares, and I charge them all....will they be okay to use in a few months or will they need a second charge before using them?

  9. #9

    Default Re: NIMH question

    You'll want to top them off just before use.

  10. #10
    Enlightened
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    Default Re: NIMH question

    [ QUOTE ]
    FlameOn said:I went with the panasonic regular charger and order a 24 pack of aa and aaas for 19.95 with free shipping from batterspace,com...

    [/ QUOTE ]
    FlameOn,

    1) How did you get free shipping at Batteryspace.com?

    2) Any comments on the quality of their batteries? I am thinking about their 2000 mAh AA NiMHs.

  11. #11
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    Default Re: NIMH question

    Wildcat - I use a MaHa MH-C401FS (on slow, mostly) which is a smart charger. See http://www.thomas-distributing.com/mhc401fs.htm Also, for a good slow charger se http://thomas-distributing.com/maha-mh-c124s.htm The C401FS monitors the battery to determine when to drop back to a trickle charge. Even so, the batteries get hotter than I like on a fast charge (about 1000ma per battery) so I normally use slow (350ma). With 2000mah NiMH batteries, that means I have between +2hrs. on fast charge & about 6hrs. on slow per set of 4 batteries.

    Flameon, anytime it's more than a week or so, I like to top off my NiMH batteries before use if it isn't too inconvenient. I still preferred NiCads for a long time after NiMHs came out - up until they had 50% or more additional capacity. The extra capacity wasn't useful because my devices (flashlights or radio, etc.) would often sit for a month between uses. Now I usually have at least one set of NiMH batteries on charge every night. -RussH

  12. #12
    Flashaholic
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    Default Re: NIMH question

    [ QUOTE ]
    FlameOn said:
    I'm basically using them in my wireless keyboard, mouse, remote controls and a few small AA flashlights so I should be okay...thanks

    [/ QUOTE ]

    The appliances listed below may all (except the flashlight) contain an Infra-Red LED, these will not work as well with rechargeables. Also as they are such low drain appliances they are not worth the financial investment in rechargeables. Certainly buy some for torches and other applications where disposable cells may prove costly, but for the others simply stick with low to medium price Alkalines.
    Note: the ones I use for this type of application cost £0.50 ($0.75)) for a pack of 4 AA Cells. Purchase of the 'premium' brand Alkalines will offer negligible benefit for such low drain applications.

  13. #13
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    Default Re: NIMH question

    oops, posted to wrong thread; deleted.

  14. #14
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    Default Re: NIMH question

    FlameOn, I use NiMH in my toothbrush and in my Logitech mouse. The mouse will discharge the cells so low that they will suffer a severe case of "voltage depression". In one case a cell was permanently damaged and I threw it out. I think I found a way to get the Logitech mouse software to warn me before the cells get too low, thanks to Empath.

    In my experience, NiMH left at room temperature for 2 months have less than 1/2 their capacity left. After 3 months they are almost empty. Maybe I have poor quality cells. They will keep about 3 times as long in the refrigerator.

    UK Owl has a good point. For such uses it would probably make more sense to buy a box of 20 or so of alkalines that places like Compusa sells cheaply.

    On the other hand I already had NiMH and chargers around the house. The NiMH AA turned out to be very handy for my digital camera, where alkalines do poorly.

  15. #15
    Unenlightened
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    Default Re: NIMH question

    I am hoping to build a 4/3 A NiMh battery pack. Does anyone have a recommendation on a charger to charge a pack of 10 of these cells? How about a good place to buy a charger?

    Thanks

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