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Thread: How long do NiMH batteries hold their charge?

  1. #41

    Default Re: How long do NiMH batteries hold their charge?

    Quote Originally Posted by lkkang View Post
    hi dnaxe, I have not heard the term TOO slowly in my life...this is the first time. Nevertheless, there is a term call "over-charge". Meaning that should the cells are already full, and the charge is still forced into the cell. Over charging is definately not healthy to the cells, because the cells will start to heat up very quickly. The pressure inside the cell will also increase and hence the recharge life cycle will reduce.
    I think that was the problem.

    After hearing so much advices from so many people... I hope you have not loose your confidence level in using re-chargeable cells. The consumer re-chargeable cells are actually quite raggered in a sense that...

    1. if you drain the cells completely.. only if you leave them idle for about say 2 ~ 3month, the cells will start to degrade... else, once you recharge them, they should return to normal again.

    2. If you once a while overcharge the cells, nothing drastic will happen also.
    To be honest, I wish my camera had a proprietary lithum power source. I think this whole thing about being able to use AA batteries is overated.

    I'm going to try eneloops though!

  2. #42
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    Default Re: How long do NiMH batteries hold their charge?

    Quote Originally Posted by kiwi2 View Post
    Oh ha.. I didn't know I was comparing apples with oranges.

    Actually, I'm only using Powerex as an eg. I'm comparing eneloop with most other brands, even by Sanyo itself. (I have 2500mAh Sanyo.) Cos I was thinking so what if the rating is a high 2700mAh but the discharge rate is faster than a lower 2000mAh eneloop?

    For eg, if I use the batteries over a period of 1-2 weeks, the 2700mAh batteries cannot sustain their power long enough. Somewhere along the way, the eneloop would ironically "catch up" and have more charge stored in it bcos it self-discharges slower. By the end of the second week, the 2700 batteries are as good as flat but the eneloop still lives on. So eventually, I need to do more frequent charging on the 2700!

    Maybe for those who use them very frequently on a daily basis may fully utilize the higher rated batteries before they could even self-discharge on their own. Am I right here?

    For me, I don't use my camera every day and it's frustrating having to charge first every time I wish to spontaneously just take it out to shoot.

    Pls correct me if I'm wrong, but I think the self-discharging phenomenon is a curse or big disadvantage in rechargeable batteries!

    Oh.. I haven't heard that storing batteries in a discharged state is no good. So if I don't use them for some time, and since they will self-discharge, I should still take them out just to charge them? Then let them self-discharge on their own, and repeat....?

    (Btw, for Powerex, it's very confusing. I didn't know the cells were from China. The batteries say Made in Japan, the simple manual has an address in the US, which I thought originated from there, and the box says the charger is made in Taiwan!! Phew... )
    hi kiwi2, you are absolutely correct in your analogy.

    I have not study the Sanyo Eneloop cells, and hence cannot make much comment. Frankly speaking , you guys might have more experience with the commercially available rechargeable cells than me. Most of the time, I deal with Lithium-ion, Lithium-polymer and other industrial grade cells. The largest rechargeable market now is the cell phone and laptop industries. I used to involved in walkie talkie , but it is getting lesser now a days.

  3. #43

    Default Re: How long do NiMH batteries hold their charge?

    Thanks lkkang for your reply... It's nice to sometimes have someone in the field we are discussing to shed more light on the technical aspects of things.

    I find it's so easy to get fooled or misguided by manufacturers' claims and all those nice sounding advertisements.

  4. #44
    Senior Member felixcat8888's Avatar
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    Default Re: How long do NiMH batteries hold their charge?

    Question for lkkang:

    I have a number of sets of the Energizer 2500 mAh and have not used them for about 10 months. I have charged them overnight but when I used a battey tester to check, 1 set says 60% and the other is 80% only the 3 set is 100%.

    How do I get them to be 100% again? Do I just change until all are 100%?

    Thanks in Advance

  5. #45

    Default Re: How long do NiMH batteries hold their charge?

    Quote Originally Posted by felixcat8888 View Post
    Question for lkkang:

    I have a number of sets of the Energizer 2500 mAh and have not used them for about 10 months. I have charged them overnight but when I used a battey tester to check, 1 set says 60% and the other is 80% only the 3 set is 100%.

    How do I get them to be 100% again? Do I just change until all are 100%?

    Thanks in Advance
    You need to "break-in" your under-used batteries. Drain the batteries to 0% and then do a full recharge and drain to 0% and recharge to full, repeat for a few cycles (e.g. 5 or more). This will take a long time. And use low current for the charging up if possible. FYI, there are products that do this easily for you. Check out POWEREX MH-C9000 WizardOne Charger-Analyzer.

  6. #46
    Senior Member felixcat8888's Avatar
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    Default Re: How long do NiMH batteries hold their charge?

    Quote Originally Posted by Lightworkz View Post
    You need to "break-in" your under-used batteries. Drain the batteries to 0% and then do a full recharge and drain to 0% and recharge to full, repeat for a few cycles (e.g. 5 or more). This will take a long time. And use low current for the charging up if possible. FYI, there are products that do this easily for you. Check out POWEREX MH-C9000 WizardOne Charger-Analyzer.

    Thanks a lot

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    Default Re: How long do NiMH batteries hold their charge?

    Quote Originally Posted by Lightworkz View Post
    You need to "break-in" your under-used batteries. Drain the batteries to 0% and then do a full recharge and drain to 0% and recharge to full, repeat for a few cycles (e.g. 5 or more). This will take a long time. And use low current for the charging up if possible. FYI, there are products that do this easily for you. Check out POWEREX MH-C9000 WizardOne Charger-Analyzer.
    perfect answer ! very professtional advice...

    I have done this test before. Infact at the third cycle, the cells is consider fully recovered. If you continue for another 2 cycles, yes ... it will be better, but the recycle time will be quite long.

    Just to take note that the machine ( battery analyser ) that does these type of cyclic charging is very expensive, normally in a range of few hundreds. Therefore, you have to consider weather the investment is worth for a low cost AA size battery.

    One cheap method is to cycle the battery manually. Meaning that you perform charging and then drain the cells for several cycles manually. Point to note is that you must drain the cells completely. Between cycles, let the cells rest for about 1/2 hour.

  8. #48
    Senior Member felixcat8888's Avatar
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    Default Re: How long do NiMH batteries hold their charge?

    Quote Originally Posted by lkkang View Post
    perfect answer ! very professtional advice...

    I have done this test before. Infact at the third cycle, the cells is consider fully recovered. If you continue for another 2 cycles, yes ... it will be better, but the recycle time will be quite long.

    Just to take note that the machine ( battery analyser ) that does these type of cyclic charging is very expensive, normally in a range of few hundreds. Therefore, you have to consider weather the investment is worth for a low cost AA size battery.

    One cheap method is to cycle the battery manually. Meaning that you perform charging and then drain the cells for several cycles manually. Point to note is that you must drain the cells completely. Between cycles, let the cells rest for about 1/2 hour.

    Meaning I can use normal charger to charge the batts and use on the digicam and let them go flat and then charge again?

  9. #49

    Default Re: How long do NiMH batteries hold their charge?

    Quote Originally Posted by felixcat8888 View Post
    Meaning I can use normal charger to charge the batts and use on the digicam and let them go flat and then charge again?
    It don't work this way.

    The Maha Powerex MH-C9000 WizardOne Charger-Analyzer uses an algorithm to refresh/break-in the cells.

    Refer to the link to have a better idea.

  10. #50
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    Default Re: How long do NiMH batteries hold their charge?

    Quote Originally Posted by felixcat8888 View Post
    Meaning I can use normal charger to charge the batts and use on the digicam and let them go flat and then charge again?
    Yes, that is exactly what I ment. Cycle the charge manually. One thing you have to remember, it is best that you completely drain the cells. For some digicam, sometimes the camera will refuse to be power up when there is still some power left inside the battery cells ( say about < 10% ). In this case, you will not be able to drain the cells "COMPLETELY".

    If you have a electronic shaver, or touch light or toy car or something that is "not so intellegent", it will be better to perform a complete drain.

    The whole idea of cyclic charging is to completely drain the cells and then fully charge them again.

  11. #51
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    Default Re: How long do NiMH batteries hold their charge?

    Quote Originally Posted by ipin View Post
    It don't work this way.

    The Maha Powerex MH-C9000 WizardOne Charger-Analyzer uses an algorithm to refresh/break-in the cells.

    Refer to the link to have a better idea.
    hi ipin, I do agree with you that the analyser will perfectly refresh the cells; in a way that it will impose minimum damage to the cells. However, are you going to spend $99 for a charger to rescue your $10 AA cells? I can easily buy 10 more cells just to play with them again..

    Anyway, the item you quoted is a good device, this is also a first time I come across this type of consumer charger that is able to perform refresh. thanks for sharing.

  12. #52
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    Default Re: How long do NiMH batteries hold their charge?

    Hi lkkang. Thanx for your contribution to the thread.

    A quick question for you: Are dead Li-Ion cells revivable? i have a completely dead laptop battery, was wondering if it was viable to do a 're-condition' instead of buy a new one.

  13. #53
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    Default Re: How long do NiMH batteries hold their charge?

    Quote Originally Posted by ST1100 View Post
    Hi lkkang. Thanx for your contribution to the thread.

    A quick question for you: Are dead Li-Ion cells revivable? i have a completely dead laptop battery, was wondering if it was viable to do a 're-condition' instead of buy a new one.
    ha ha... interesting question. If I can recondition a dead laptop battery , I can win the next NOBEL PRICE already. Maybe NASA will hire me also...

    brother, Dead means dead already lah... How can a dead man come alive again.

    I just spend $100+ to replace my own laptop battery about 2 weeks ago... "Boh bian" lah friend , everything has a life span, a normal battery life span is about 1 year, if you don't mind a little shorter use time, you may continue to use the battery for another about say 1 or 2 more years.. then the cells will be completely "dead" or cannot hold charge anymore.

  14. #54
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    Default Re: How long do NiMH batteries hold their charge?

    Quote Originally Posted by lkkang View Post
    Yes, that is exactly what I ment. Cycle the charge manually. One thing you have to remember, it is best that you completely drain the cells. For some digicam, sometimes the camera will refuse to be power up when there is still some power left inside the battery cells ( say about < 10% ). In this case, you will not be able to drain the cells "COMPLETELY".

    If you have a electronic shaver, or touch light or toy car or something that is "not so intellegent", it will be better to perform a complete drain.

    The whole idea of cyclic charging is to completely drain the cells and then fully charge them again.
    Thanks Ikkang. Will do that and refresh them

  15. #55

    Default Re: How long do NiMH batteries hold their charge?

    Quote Originally Posted by lkkang View Post
    hi ipin, I do agree with you that the analyser will perfectly refresh the cells; in a way that it will impose minimum damage to the cells. However, are you going to spend $99 for a charger to rescue your $10 AA cells? I can easily buy 10 more cells just to play with them again..

    Anyway, the item you quoted is a good device, this is also a first time I come across this type of consumer charger that is able to perform refresh. thanks for sharing.
    I spent $99 to not only refresh all (quite a number of sets) of my batteries and to keep them in tip top performance as I know thay they'll perform during my shoots. BTW, any photographer would have several sets and if they are well taken for, they would be able to serve the photographer for some time.

    After weighing the cost aspect issues, I went ahead and bought it. I have since made back the initial cost of it.

    And yup! It's a device!

  16. #56

    Default Re: How long do NiMH batteries hold their charge?

    I bought the POWEREX MH-C9000 WizardOne Charger-Analyzer for only $79.00 from eastgear while thay were having promotion some months back, and yes I bought 3 sets! Because I need to charge 12 batteries all at one go. I revived dunno how many "dead" AA NiMH batteries, i lost count But the good thing about this charger is you can set the charging current as you wish so I can roughly "control" the charging time (by doing some simple calculation) while optimising the NiMH batteries.

  17. #57

    Default Re: How long do NiMH batteries hold their charge?

    Quote Originally Posted by lkkang View Post
    perfect answer ! very professtional advice...

    I have done this test before. Infact at the third cycle, the cells is consider fully recovered. If you continue for another 2 cycles, yes ... it will be better, but the recycle time will be quite long.
    My personal experience. I got some 2300 AA that had "slept" for 2 years. I have to cycle charged them 11 times, yes 11!!! times, to get those batteries to work like it is new. Well, most people will just throw it away after 2x charges (because they thought the batteries probably go kaputt)

  18. #58

    Default Re: How long do NiMH batteries hold their charge?

    Quote Originally Posted by Lightworkz View Post
    I bought the POWEREX MH-C9000 WizardOne Charger-Analyzer for only $79.00 from eastgear while thay were having promotion some months back, and yes I bought 3 sets! Because I need to charge 12 batteries all at one go. I revived dunno how many "dead" AA NiMH batteries, i lost count But the good thing about this charger is you can set the charging current as you wish so I can roughly "control" the charging time (by doing some simple calculation) while optimising the NiMH batteries.
    Now that you mentioned it, I might have bought it at $79 too! Cannot really confirm until I look at the receipt. I know that I didn't buy it when it first came out.

  19. #59

    Default Re: How long do NiMH batteries hold their charge?

    Quote Originally Posted by ipin View Post
    I spent $99 to not only refresh all (quite a number of sets) of my batteries and to keep them in tip top performance as I know thay they'll perform during my shoots. BTW, any photographer would have several sets and if they are well taken for, they would be able to serve the photographer for some time.

    After weighing the cost aspect issues, I went ahead and bought it. I have since made back the initial cost of it.

    And yup! It's a device!
    Looks like it's time for me to get one of those chargers also.

  20. #60

    Default Re: How long do NiMH batteries hold their charge?

    Quote Originally Posted by ipin View Post
    Now that you mentioned it, I might have bought it at $79 too! Cannot really confirm until I look at the receipt. I know that I didn't buy it when it first came out.
    I just bought some eneloops!

    I'll wait till a similar drop (or a new model - come on, USB control) before buying a charger - will just use a slow charger...

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