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Thread: How to verify AA nicad or nimh with no label

  1. #1
    Flashaholic
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    Default How to verify AA nicad or nimh with no label

    I have 5 AA cells that I got out of a cheap rechargeable spot light.
    I figured that they were cheap ni-cad cells but they are holding 1.28 volts
    even after 2 or 3 months since being charged on a universal charger.
    They also look like the 1st generation eneloops. Could you tell by the weight?

    How does the charger determine which charge program to use?
    Leslie W. Knight

  2. #2
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    Default Re: How to verify AA nicad or nimh with no label

    makes no real difference ...

  3. #3
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    Default Re: How to verify AA nicad or nimh with no label

    Quote Originally Posted by yellow View Post
    makes no real difference ...
    huh?
    I would like to know what cells I have if there is an easy way to tell.
    Leslie W. Knight

  4. #4

    Default Re: How to verify AA nicad or nimh with no label

    I looked up online and the weights for some sanyo Nicads were 23g-24g compared to 26g for AA Nimh Eneloops there is not much in it but that's not to say some nicads could weigh more of less depending on who made them but if you have an accurate weighing scale maybe you could see.

    As far as charging is concerned most modern smart chargers can do both nicads and Nimh so there is no problem charging them up.

    I think the best way to determine what batteries you have is charging them up and comparing them to a known Nimh buy putting them in something like a flashlight that is known to run for 2hours with a 2000mah eneloop and then comparing the unknown battery you can roughly work out the capacity.

    As most nicad AA have a capacity between 600mah-1100mah compared to AA eneloops 2000mah you should be able to see the difference in runtime.
    But it could also be that you have Nimh that have lost its capacity.

    What model of spotlight is it as it may be possible to search for that model and see if it came with Nicads or Nimh.

    Hope that helps you out.

  5. #5
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    Default Re: How to verify AA nicad or nimh with no label

    I think it was "Workforce " from Home Depot
    Anyway it was a cheapo.
    I will test then in my old 4AA camera that is a battery eater extraordinaire.
    Leslie W. Knight

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    Default Re: How to verify AA nicad or nimh with no label

    Interesting question. The only thing that I can think of is that when charged on a NiMH charger that utilizes -dV termination, NiCd cells charge to about 0.1 to 0.2 Volt higher than NiMH cells. I've seen them go to 1.70 or so myself, a few times, as opposed to NiMh cells which typically top out at 1.45-1.55 Volt. This is also related to why you can charge NiCd cells on a NiMH charger, but not the other way around. NiMH cells are much more sensitive to overcharge. Old NiCd chargers use a higher voltage and end up overcharging NiMH cells.

    As for self discharge, this depends on the quality of the cell, which is unknown. Good NiCd cells have a much lower self discharge rate than conventional NiMH cells, typically about a third, or less. Then again, nowadays there are not to many "good" NiCd cells around. Most Chinese ones are not so great, and Sanyo in Japan is the only real source that I know of for high quality NiCd cells and are also quite expensive. I seriously doubt a low end light would come equipped with them, they'd cost more than the light!

    Best guess is they're NiMH. As I said though, an interesting question, as to how to tell for sure.

    Dave

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    Default Re: How to verify AA nicad or nimh with no label

    Well. they took 60 pictures with flash without a bobble and still held 1.26 volts.
    Solution: Toss the dumb charger and just use the C808 because these batteries are
    awesome even if the voltage is below normal.

    Found it on homedepot.com. It says nimh batteries. Funny thing is the run time is 20
    minutes ( box says 8 hours ) on a 20 hour charge. What do you expect for under $10.00 LOL?
    Last edited by lwknight; 07-22-2012 at 05:23 PM.
    Leslie W. Knight

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    Default Re: How to verify AA nicad or nimh with no label

    Quote Originally Posted by lwknight View Post
    How does the charger determine which charge program to use?
    I thought that was Your question ...

  9. #9
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    Default Re: How to verify AA nicad or nimh with no label

    Quote Originally Posted by yellow View Post
    Originally Posted by lwknight

    How does the charger determine which charge program to use?
    I thought that was Your question ...
    Humm, maybe, but I think lwknight was asking how to tell which kind of cells he has.

    As for this particular question the answer is, it doesn't. Modern NiMH chargers which use -dV (which most do) simply terminate charge at the -dV voltage drop. It makes no difference what chemistry the cell is. NiCd cells simply terminate at the -dV signal, which, as I said, occurs at 0.1-0.2V higher than NiMH.

    Older "dumb" type NiCd chargers however, that do not use -dV, charge at a higher voltage and can damage NiMH cells, due to overcharge. Again, this is why both NiCd and NiMH cells can be charged in a modern NIMH charger, but damage is likely to occur if NiMH cells are charged in an older NICd charger.

    Dave

  10. #10
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    Default Re: How to verify AA nicad or nimh with no label

    Older "dumb" type NiCd chargers however, that do not use -dV, charge at a higher voltage and can damage NiMH cells, due to overcharge. Again, this is why both NiCd and NiMH cells can be charged in a modern NIMH charger, but damage is likely to occur if NiMH cells are charged in an older NICd charger.

    Dave
    I have a dumb charger so that is part of why it mattered what chemistry the batteries were.
    The other part is that you can get good batteries cheaper than eneloops by buying the H.D. Workforce light
    on sale and wrecking it out for the batteries. The regular price is under $10.00.

    Since I found out that they are nimh, I put them to the real world test and they passed with flying colors.
    BTW: off the charger voltage was 1.40 volts so even at 1.28 volts from sitting 3 months in the desk drawer
    and I got 60 pictures without a bobble from an infamous battery eater camera.
    Leslie W. Knight

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