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Thread: NiMH Battery Question -- do they get hot when charging??

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    Flashaholic* avusblue's Avatar
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    Default NiMH Battery Question -- do they get hot when charging??

    I just acquired a used digital camera from a CPF'er, that included a set of NiMH AA batts and a charger. Well the batteries he sent won't hold a charge, so I went to Wal-Mart and bought a set of Energizer 2100 mah NiMH rechargeables (4 for $9.83 - great deal!). I put them in the charger that was sent by the CPF'er (a Panasonic 6-hour model) and when I checked them 6 hours later they were quite hot to the touch. They seem fully charged, but I didn't apply an extended runtime yet.

    Is it normal for NiMH batteries to get hot when charging? Might this be a problem in the charger? Might this be why the supplied batts (no-name 1800 mah) didn't charge?

    This is my first exposure to rechargeable NiMH AA's, so all ideas are appreciated.

    Thanks,

    Dave

  2. #2

    Default Re: NiMH Battery Question -- do they get hot when charging??

    Yes, it is quite normal for the type of charger you have (one that charges in less than say 12 hours. The temperature rises quite rapidly as the charge nears 100%, if the rate of charge is high enough. In fact some chargers use a ten or fifteen degree C rise to 'detect' end of charge.

    I don't know your charger, but I suspect it depends on a small but predictable *drop* in cell voltage about that same time. Anything that interferes with this (poor contact, abuse of the cell, etc.) fouls this up.

    The 'fall back certain' charger is cheap but slow. It's the 'trickle' charger, typically taking up to a day. Perhaps a 'ride or two' on one might breathe new life in your 1800s? The cells are really quite robust (unless you overheat them, severely overcharge or reverse charge them). And most all the CPF folks seem quite up front to me, I wouldn't throw them out.......

    Doug Owen

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    Flashaholic* kingkong's Avatar
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    Default Re: NiMH Battery Question -- do they get hot when charging??

    it is normal for any batteries to get warm when you charge them. The NIMH that I gave you is still good. I just use them for about 3 times. if you dont us them, can you send it back to me. I hate for you to throw away.

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    Flashaholic* avusblue's Avatar
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    Default Re: NiMH Battery Question -- do they get hot when charging??

    Thanks guys. I'll try cycling the ones that came with the camera again. When I charged them fully, and then put them in, they only ran the camera for about 5 minutes. How does one "wake them up" other than running through charge / discharge cycles?

    Dave

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    Flashaholic* shankus's Avatar
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    Default Re: NiMH Battery Question -- do they get hot when charging??

    How long do the 2100s run the camera?

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    Flashaholic* FalconFX's Avatar
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    Default Re: NiMH Battery Question -- do they get hot when charging??

    2100s should run a typical digicam for at least 200+ shots...

    Batts in "fast" chargers get quite hot, as hot, if not hotter, than body temp. And in the Rayovac pressure cooker (PS4), it can get downright explosive...

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    Flashaholic* star882's Avatar
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    Default Re: NiMH Battery Question -- do they get hot when charging??

    My 2 hour charger gets the cells pretty hot while charging.

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    Flashaholic* FalconFX's Avatar
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    Default Re: NiMH Battery Question -- do they get hot when charging??

    Anytime you feed a AA battery more than 400mah, it'll get hot... There's no way around it, unless you stick it in a fridge. And even then, it'll still get hot... It's a resistor, alright...

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    Default Re: NiMH Battery Question -- do they get hot when charging??

    [ QUOTE ]
    FalconFX said:
    Anytime you feed a AA battery more than 400mah, it'll get hot... There's no way around it, unless you stick it in a fridge. And even then, it'll still get hot... It's a resistor, alright...

    [/ QUOTE ]
    Here's my conclusion-after charging thousands of NimH cycles....

    My much used CCrane unit (pulse) charges a single AA NimH @ 700mA. This causes the cell to sometimes get very warm, but not too hot to hold in a closed fist.

    IMO-if you can't wrap your fingers around the cell and hold it without discomfort-...you are definitely hurting (at the very least), the actual capacity of the cell.

    p.s.-I've got a half dozen NimHs that I have overheated with other chargers, and I'll gladly sell THOSE batteries to anybody--dirt cheap. [img]/ubbthreads/images/graemlins/icon15.gif[/img]

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    Default Re: NiMH Battery Question -- do they get hot when charging??

    I have been thinking of getting the CCrane Quick Charger to replace my cheap one from Radioshack, which gets the batteries quite hot. Is the CCrane charger really worth it?

  11. #11
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    Default Re: NiMH Battery Question -- do they get hot when charging??

    [ QUOTE ]
    Pi_is_blue said:
    I have been thinking of getting the CCrane Quick Charger to replace my cheap one from Radioshack, which gets the batteries quite hot. Is the CCrane charger really worth it?

    [/ QUOTE ]
    IMO, in the $35. range-I sure think it is. [img]/ubbthreads/images/graemlins/thumbsup.gif[/img]

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    Default Re: NiMH Battery Question -- do they get hot when charging??

    What charger are we talking about? Any of the slow chargers I ahve used don't get the batteries hot. The 401 on the 5 hour setting only gets the batteries warm. I am asking because I have a guess this is a timer charger and might not fully charge 2100mA's. And might over charge smaller cells, hard to say without knowing the charger.

  13. #13
    Flashaholic* FalconFX's Avatar
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    Default Re: NiMH Battery Question -- do they get hot when charging??

    I'm guessing we're all taking about "fast" chargers, in the 1-2 hour range to charge up a 2000+mah AA cell... So something like a 700+ma current charger...

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    Default Re: NiMH Battery Question -- do they get hot when charging??

    [ QUOTE ]
    Brock said:
    What charger are we talking about? Any of the slow chargers I ahve used don't get the batteries hot. The 401 on the 5 hour setting only gets the batteries warm. I am asking because I have a guess this is a timer charger and might not fully charge 2100mA's. And might over charge smaller cells, hard to say without knowing the charger.

    [/ QUOTE ]
    Is that "401" the Maha? -if you were asking me. [img]/ubbthreads/images/graemlins/grin.gif[/img]
    Not having any experience with Maha, I can't comment. BTW-how much does it sell for?

    p.s.-the CCRanes I use all the time a DO nicely and Completely charge up my 1800 NiMh cells although taking about 15-20 min. longer to charge than my older NiMh AA 1200s-without getting the cells too hot to hold in a closed fist. (right out of the charger).

    There are no doubt more advanced units available, but I haven't noticed any in the $35-40 price range.

  15. #15
    Flashaholic* FalconFX's Avatar
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    Default Re: NiMH Battery Question -- do they get hot when charging??

    The Maha C401FS is in the $35-$40 range from Thomas Distributing...

    From 100-120min to 5 hours of charging and 4 separate channels, it's quite possibly the best NiMH AA/AAA charger out there right now...

  16. #16
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    Default Re: NiMH Battery Question -- do they get hot when charging??

    Thanks, if I didn't have a lot of "C" and "D" cells to charge, I'd be lookin' at that one for sure.

  17. #17

    Default Re: NiMH Battery Question -- do they get hot when

    I think when Membr123 says the amperage of the ccrane charger is 700ma with a single aa battery he means just that; the unit is charging a single battery instead of 4 batteries..since the ccrane charges up to 4 batteries in parallel the average amps 1 battery out of the 4 batteries would see would be 175 ma.. so the batteries stay cool.
    I haven't measured the actual amps the ccrane puts through various types of batteries though, does it always put out the same amperage?

  18. #18

    Default Re: NiMH Battery Question -- do they get hot when charging??

    I just posted a preliminary review of the Lenmar Mach 1 Gamma charger if you are interested. No more hot batteries

    http://www.candlepowerforums.com/ubb...rue#Post296963

  19. #19
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    Default Re: NiMH Battery Question -- do they get hot when

    [ QUOTE ]
    TedtheLed said:
    I think when Membr123 says the amperage of the ccrane charger is 700ma with a single aa battery he means just that; the unit is charging a single battery instead of 4 batteries..since the ccrane charges up to 4 batteries in parallel the average amps 1 battery out of the 4 batteries would see would be 175 ma.. so the batteries stay cool.
    I haven't measured the actual amps the ccrane puts through various types of batteries though, does it always put out the same amperage?

    [/ QUOTE ]
    Right you are, Ted-according to the charge time tables in the manual, the parallel circuit requires twice th time for twice the # of cells.

    Example: 1300mAh AAs (1 cell)=42 min.
    (2 cells)=84 min. etc. (4 cells)=168 min.---doing my sums.... [img]/ubbthreads/images/graemlins/grin.gif[/img] 2h.48m.

    It has three things going for it: simple to use, easy on the cells, and very reliable.

  20. #20
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    Default Re: NiMH Battery Question -- do they get hot when

    The Maha 401 is a smart charger in both fast and slow modes. In my experience, even charging in fast mode, the 401 charges cooler than any other charger I have used including the 204 and it is charging at twice the rate (1000mA vs 500mA). They claim that it is due to their "unique FLEX NEGATIVE PULSE algorithm."

    Someone has said it before but worth the repeat, " A good charger is more important than the battery." Without it you won't get maximum benefit from your cells and you'll cut their life drastically. What you'll save on a cheap charger will be far outspent with what you'll waste on prematurely ruined cells.

    I'm sure that there are some other good chargers out there, but I don't know for sure about them. I do know about the 401 and highly recommend it. In addition, it comes with an unheard of lifetime warranty.

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    Default Re: NiMH Battery Question -- do they get hot when

    I would agree that a good charger is more important then the batteries. I used to use a slow overnight timed charger and 1200mA's, but I never got more then 30 shots on my digicam, then I bought 1600mA and they ran about 40 shots. Then I bought the MAHA 204 and suddenly even my old 1200's were running 60 shot between charges. It really amazed me how much different the charger makes.

    In any case I think avusblue, the starter of this thread, is using a slow 6 hour charger, not the MAHA 204 or 401. So again my guess is the older charger (Panasonic 6-hour model) might be cooking the batteries, but I can't say for sure since I don't know the charger at all. It is really hard to say without knowing the temp of the batteries compared to how hot they get with my different chargers.


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    Flashaholic* shankus's Avatar
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    Default Re: NiMH Battery Question -- do they get hot when

    For C & D cells, this charger looks promising:
    ACCUPOWER 20 CHARGER

    I might get one of these soon.


    Another smart AAA & AA charger I was looking at is:
    iPowerUS FC-501 "Smart" Charger

  23. #23
    Flashaholic bluewater's Avatar
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    Default Re: NiMH Battery Question -- do they get hot when charging??

    Newbie question here....how do you know if your charger is fully charging the batteries? I have a new charger, and new 600ma AAA and 2200ma AA's. Can you tell by the voltage alone?

  24. #24

    Default Re: NiMH Battery Question -- do they get hot when charging??

    The PS4 is the 1-hour charger, right? Energizer is still selling their 1-hour charger, which I won't use any more because I think the batts get too hot (and stay too hot for too long).

    What might be more "explosive" (or not, I hope) is the new 30 minute charger Energizer has for sale at Sam's club, with 4x1850mAh AAs for $25. Tempting to try, but I'm still looking for an EE job here so I'm a bit more cautious about trying new electronics I don't have a need for. The 401s and CCrane do me just fine.

    The 30 min charger looks interesting. It's a bit bigger than the 1-hour, and has the cells arranged with one cell on each side of it, rather than all together 4-in-a-row.

    The Energizer 2100s @ Wal-Mart were exciting news to me yesterday. I picked up two 4-packs. Alas, I have no AA using digicam. Sony DSC-S85 uses their capacious Infolithium M pack, and the Nikon 2500 I carry around has a 1 Ah proprietary LiIon pack. In fact, I notice more of the devices out there are using LiIon, and often proprietary packs or built-in non-replaceable batts, rather than easily obtained AA or AAA cells. Not a good trend IMHO, especially the built-in packs (Palm Zire 71, Apple iPod).

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    Flashaholic* FalconFX's Avatar
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    Default Re: NiMH Battery Question -- do they get hot when charging??

    30 minutes from dead to near full charge means it's got to be delivering ~4Amps to those batteries... I don't know if that's a particularly good idea. I certainly hope it's got all the safety features (negative DeltaV sensing, maybe heat sensing as well) to prevent the same problems that plagued the PS4...

  26. #26

    Default Re: NiMH Battery Question -- do they get hot when charging??

    Yeah, you're right, that must be some impressive power brick with it, though if it's like the 1-hour Energizer charger, I think it takes 12 or 18V in and then converts it to a lower voltage for charging. Still, that's over 20 watts.

    I see PowerEX/Maha has leapfrogged Energizer/Sanyo in capacity again so the 2100s are a little less exciting. I'm keeping one 4-pack to run a 4-cell halogen light, but sold the other set to some friends who just got a Canon A70 digicam. I offered some of my 1800s for free, but they thought (and I agreed) that for the cam the 2100s were worth ten bucks. One of my 204 chargers is on indefinite loan to them.

    After years of using Sony cameras with the infoLithium batteries, it's weird to see that other digicams have no more battery status indication than a low-battery idiot-light.

  27. #27
    Enlightened
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    Default Re: NiMH Battery Question -- do they get hot when charging??

    My understanding is that something like 10 deg. F over ambient is normal and that ambient shouldn't be much over 80 F.

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    Default Re: NiMH Battery Question -- do they get hot when charging??

    i've just picked up a new aa/aaa charger from radio shack that has a delta peak detection, and also thermal shutdown if the batteries get too hot. This sucker also has a timer shutdown if it seems to be going on too long and not peaking for risk of blowing up a battery. Charge rate can be set at 1amp for nicad AA's and 2amps for nimh AA's. not a bad charger cause my most favorite feature is that is can charge 1 to 4 batteries! perfect for my toys using odd numbers (LGI). has anyone tried this charger? i got it for $69.99 CDN at rat shack.

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