NiMH 2500 mAh Scorching upon charge

Discussion in 'Digital Photography' started by Atreju, Oct 12, 2004.

  1. Atreju

    Atreju Guest

    I removed them from the charger after about 45 minutes. They were
    extremely HOT!

    Any idea if this is normal?

    Atreju, Oct 12, 2004
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  2. Atreju

    Bob Salomon Guest

    Not in a good charger.
    Bob Salomon, Oct 13, 2004
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  3. If they are IC3 they may be. Mine are 2000 NiMH made by Ray-O-Vac which are
    IC3 and a fan blows while charging and it's still fairly warm.
    Larry R Harrison Jr, Oct 13, 2004
  4. Atreju

    Atreju Guest

    The charger and the batteries came in a package together! This didn't
    happen the last time I charged them. Could this be because they were
    already charged most of the way and I was just trying to give them a
    bit of extra juice. Maybe the charger does not adequately detect their
    current status.

    Atreju, Oct 13, 2004
  5. Atreju

    Larry Guest

    The overnight chargers leave the batteries cold, but usually the less

    The one hour cargers leave the batteries warm but MOST have overcharge

    The half hour chargers (all that I have seen/used) leave them HOT to the
    touch, But ALL that I have seen have overcharge protection. (they dont tend
    to all finished charging at the same time, and depend on a colored LED for
    each cell to let you know)

    The 15 minute chargers and their special batteries come with warnings in the
    paperwork about the heat produced (and AFAIK all the 15 minute chargers have
    cooling fans in them) ALL have overcharge protection, most charge each
    battery in its own circuit (as with the half hour chargers they dont tend to
    all finished charging at the same time, and depend on a colored LED for each
    cell to let you know)
    Larry, Oct 13, 2004
  6. Getting fairly warm is normal, depending on the charger, but too hot to
    hold is not normal.

    What kind of charger is it? Does it detect when the batteries are fully
    charged, or just charge for a fixed time? Fixed-time chargers assume
    that the batteries are fully discharged when you start; if the batteries
    do in fact have some charge in them, the charger will overcharge them
    and they can get hot.

    Dave Martindale, Oct 14, 2004
  7. Atreju

    Markus L Guest

    Unfortunately, most devices (cameras, mp3 players etc.) stop a long time
    before the cells are fully discharged. Reason is a lousy design which
    requires a certain minimum voltage to operate. I once measured the remaining
    capacity of a 2400mAh NiMH AA cell after my iRiver mp3 player shut down:
    Around 1100mAh, which is 45% of the cell's rated capacity! Any fixed-time
    charger will heavily overload such a cell. Workaround is to use a fast
    charger having a reliable termination mechanism.
    Markus L, Oct 14, 2004
  8. Absolutely correct. A more sophisticated/intelligent charger will also
    get a longer life time from all cells. NiMH's in particular will
    suffer from excessive heating, something a good charger can avoid.

    Bart van der Wolf, Oct 14, 2004
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