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How can you tell a NiHM from a NiCAD battery

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  • 19-06-2005 6:11pm
    #1
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 91,754 Mod ✭✭✭✭


    Braun 2540 Shaver with 5 mins battery life
    The rechargable battery inside is AA size with "HR" marked on it. Voltage is 1.305 volts.

    Both have similar voltages and it's not charging up to the capacity of an old NiCAD

    How can I tell if it's NiMH or NiCAD ??


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    #2
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 91,754 Mod ✭✭✭✭Capt'n Midnight


    It seems that NiMH are heavier than NiCad's and slightly higher voltage fully charged 1.3V vs. 1.25V


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    #3
    Tar.Aldarion
    Moderators, Science, Health & Environment Moderators, Social & Fun Moderators, Society & Culture Moderators Posts: 60,098 Mod ✭✭✭✭Tar.Aldarion


    glad ya found out, cos i sure didnt know :)


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    #4
    kasintahan
    Closed Accounts Posts: 1,010 ✭✭✭kasintahan


    It's almost certainly Ni-CD, despite it being the older tech.

    Cadmium is preferred in motorised devices (model cars etc) and pro flash units because...

    (a) it's charge/discharge rate goes up to 10C (basically it can be charged/output 10 times it's nominal mAh rate, that's really fast) as oppose to 3C for NI-MH.

    (b) it's rechargeable 1000 times as oppose to 500 times for Ni-MH

    (c) it's lighter (in mAh per kilo).

    (d) it's cheaper.

    of course Cd is REALLY REALLY poisonous so I avoid it where possible.


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    #5
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 91,754 Mod ✭✭✭✭Capt'n Midnight


    I reckoned it whas NiMH in the shaver because
    Heavier cell ~ 18g NiCAD AA Vs. ~ 26g NiMH AA
    With shavers battery life is more important than high drain, since they are supposed to last a good bit more than 6 minutes I reckon the ability to discharge at 10C wasn't a design spec

    there is little to choose in the weight per mAH - NiMH cells are denser so you have more power in the same size.

    and no I wouldn't fancy being anywhere near a NiCAD charging at 10C


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    #6
    CathalMc
    Registered Users Posts: 225 ✭✭CathalMc


    I also imagine NiMH as NiCad is penalised by tax in Europe so companies would tend to use NiMH. Also, the name of that device is different in America suggesting that it might have a different charging circuit. Maybe.


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