Battery charger & hot batteries

Discussion in 'Digital Photography' started by MikeM, Oct 30, 2007.

  1. MikeM

    MikeM Guest

    I have been trying to find a battery charger that doesn't overheat my
    AA batteries. The latest one I tried was an Energizer, CH1HR. I tried
    topping up a partially depleted set of 2700 AAs. In the short time it
    took for them to be fully charged they were so hot I couldm't hold
    them. Even the 2500 AAs that came with the charger got very hot. Am I
    correct in thinking that if batteries get too hot to handle will be
    damaged by the charger?
    MikeM, Oct 30, 2007
    #1
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  2. MikeM

    Dave Cohen Guest

    On Tue, 30 Oct 2007 00:22:31 +0000, MikeM wrote:

    > I have been trying to find a battery charger that doesn't overheat my
    > AA batteries. The latest one I tried was an Energizer, CH1HR. I tried
    > topping up a partially depleted set of 2700 AAs. In the short time it
    > took for them to be fully charged they were so hot I couldm't hold
    > them. Even the 2500 AAs that came with the charger got very hot. Am I
    > correct in thinking that if batteries get too hot to handle will be
    > damaged by the charger?


    Don't know how hot they can get before the heat ruins them, but hands are
    a different matter.

    I've noticed:
    1) Some cells seem to get hotter than others under the same charge
    conditions.
    2) A lower charge rate will help
    3) Most of the high temperature seems to occur during the latter part of
    the cycle.

    My charger is supposed to shut off for a bad cell or excessive heat. I'm
    not sure what their definition of excessive heat might be but I've had
    some cells get uncomfortably hot without the charger complaining. The
    high temperature doesn't appear to cause any immediate harm, long term who
    knows.
    Dave Cohen
    Dave Cohen, Oct 30, 2007
    #2
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  3. MikeM

    MikeM Guest

    On a recent 3-month overseas trip I used a Vivitar charger that didn't
    charge individual batteries separately, didn't claim to detect
    excessive temps or detect dead batteries. When using it the batteries
    got very hot, but not as hot as the Energizer charger I got ro replace
    it that charged individual batteries, claimed to detect excessive heat
    and dead batteries. On the trip I carried 3 sets of spare battreies
    for my 2 cameras. By the time I returned home I noticed that most of
    my sets of batteries didn't last very long, much shorter time than
    when I left on the trip. The Energizer charger detected that there was
    at least 1 dead battery in 3 of the sets.

    Mike


    On Tue, 30 Oct 2007 00:45:37 GMT, Dave Cohen <> wrote:

    >On Tue, 30 Oct 2007 00:22:31 +0000, MikeM wrote:
    >
    >> I have been trying to find a battery charger that doesn't overheat my
    >> AA batteries. The latest one I tried was an Energizer, CH1HR. I tried
    >> topping up a partially depleted set of 2700 AAs. In the short time it
    >> took for them to be fully charged they were so hot I couldm't hold
    >> them. Even the 2500 AAs that came with the charger got very hot. Am I
    >> correct in thinking that if batteries get too hot to handle will be
    >> damaged by the charger?

    >
    >Don't know how hot they can get before the heat ruins them, but hands are
    >a different matter.
    >
    >I've noticed:
    >1) Some cells seem to get hotter than others under the same charge
    >conditions.
    >2) A lower charge rate will help
    >3) Most of the high temperature seems to occur during the latter part of
    >the cycle.
    >
    >My charger is supposed to shut off for a bad cell or excessive heat. I'm
    >not sure what their definition of excessive heat might be but I've had
    >some cells get uncomfortably hot without the charger complaining. The
    >high temperature doesn't appear to cause any immediate harm, long term who
    >knows.
    >Dave Cohen
    MikeM, Oct 30, 2007
    #3
  4. MikeM

    Ron Hunter Guest

    MikeM wrote:
    > On a recent 3-month overseas trip I used a Vivitar charger that didn't
    > charge individual batteries separately, didn't claim to detect
    > excessive temps or detect dead batteries. When using it the batteries
    > got very hot, but not as hot as the Energizer charger I got ro replace
    > it that charged individual batteries, claimed to detect excessive heat
    > and dead batteries. On the trip I carried 3 sets of spare battreies
    > for my 2 cameras. By the time I returned home I noticed that most of
    > my sets of batteries didn't last very long, much shorter time than
    > when I left on the trip. The Energizer charger detected that there was
    > at least 1 dead battery in 3 of the sets.
    >
    > Mike
    >



    The question is how hot? If they get too hot to leave your finger on
    them, then that is bad for the batteries, and will shorten their useful
    life. You didn't mention how long these chargers take to charge the
    batteries. Generally, the faster the charge, the hotter the batteries
    will normally get.
    Setting the charger in a place with good airflow will certainly help,
    but if the batteries get too hot to touch, you might want to investigate
    a better charger. I have a MAHA that only gets the batteries warm, and
    then only near the end of the 3-4 hour charging cycle.
    Ron Hunter, Oct 30, 2007
    #4
  5. MikeM

    Guest

    On Tue, 30 Oct 2007 00:22:31 GMT, MikeM <>
    wrote:

    >I have been trying to find a battery charger that doesn't overheat my
    >AA batteries. The latest one I tried was an Energizer, CH1HR. I tried
    >topping up a partially depleted set of 2700 AAs. In the short time it
    >took for them to be fully charged they were so hot I couldm't hold
    >them. Even the 2500 AAs that came with the charger got very hot. Am I
    >correct in thinking that if batteries get too hot to handle will be
    >damaged by the charger?


    Some chargers electronics can't handle topping off mostly charged
    batteries without overheating them. If you have one of these, it
    sounds like you do, don't use it for topping off.
    , Oct 30, 2007
    #5
  6. MikeM

    Dave W Guest

    I think the only way a fast charger knows when to stop is by sensing
    the temperature rise, because the voltage across the cells does not
    change drastically at end of charge.

    Dave W
    Dave W, Nov 1, 2007
    #6
  7. MikeM

    Guest

    On Thu, 01 Nov 2007 07:54:43 -0700, Dave W <>
    wrote:

    >I think the only way a fast charger knows when to stop is by sensing
    >the temperature rise, because the voltage across the cells does not
    >change drastically at end of charge.
    >
    >Dave W


    Some might but most high tech newer fast chargers sense a voltage
    change or dip to shut down. I have seen these type overheat a NIMH
    battery if the battery was mostly charged to begin with.

    Best bet is to just use a dumb slow charger (130 ma) for topping off.

    Another good idea is to use the same cheap dumb chargers hooked
    to a timer. Set the timer to turn on just one or two hours a day. It
    will never overheat or damage the battery when it is used this way.
    I now have all my spare batteries hooked up this way. I am never
    without a "topped off" battery. I only use smart chargers when I'm
    on the road.
    , Nov 1, 2007
    #7
  8. MikeM

    ransley Guest

    On Nov 1, 2:50 pm, wrote:
    > On Thu, 01 Nov 2007 07:54:43 -0700, Dave W <>
    > wrote:
    >
    > >I think the only way a fast charger knows when to stop is by sensing
    > >the temperature rise, because the voltage across the cells does not
    > >change drastically at end of charge.

    >
    > >Dave W

    >
    > Some might but most high tech newer fast chargers sense a voltage
    > change or dip to shut down. I have seen these type overheat a NIMH
    > battery if the battery was mostly charged to begin with.
    >
    > Best bet is to just use a dumb slow charger (130 ma) for topping off.
    >
    > Another good idea is to use the same cheap dumb chargers hooked
    > to a timer. Set the timer to turn on just one or two hours a day. It
    > will never overheat or damage the battery when it is used this way.
    > I now have all my spare batteries hooked up this way. I am never
    > without a "topped off" battery. I only use smart chargers when I'm
    > on the road.


    A battery is fully charged just when its temp starts to rise and volts
    drop, at least thats how Nicads are, Are you sure it isnt the charger
    itself getting hot. I cant see how fast chargers are safe for the long
    run, I use a 3-5 hr sony charger thats given good battery life.
    ransley, Nov 1, 2007
    #8
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