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Question on rechargeable batteries

Discussion in 'Electronic Repair' started by Michael Muderick, Sep 6, 2003.

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  1. I have a Dewalt 12 v. rechargeable drill and a Wahl Soldering pencil iron.
    New batteries in both - the drill about a year ago, and the iron about two.
    I don't use either of them very much. I leave them in the chargers, as
    indicated by the manufacturers to be OK. Yet when I do use them, they seem
    to die prematurely. I maybe get about 15 good minutes out of the drill, and
    2 or 3 connections with the iron.

    I was told that because of the memory effect of the batteries, that leaving
    them in the chargers when not using them, actually causes this. I should
    have just charged them an hour or day before I need them, and not leave them
    in the charger. But then they are not ready for use when unexpectedly
    needed.

    1. Is the damage irreversible?
    2. What is the best solution to this problem?

    TIA
     
  2. Tom

    Tom Guest

    Possibly reversible.... Run them down , let cool for an hour, and charge for
    the prescribed amount of time. Do this a few times- it might increase the
    hold.
    Then look for a cheap apliance timer- the kind you plug into the wall,
    either 24 hour time or 7 day.
    Set it to "top-off" your battery while not in normal use. Depending on the
    charge current, somewhere between 1 hour/day to 1 hour/week.

    Although aimed at nicds for radio controled flying- this website has some
    good general info.
    http://www.rcbatteryclinic.com/
     
  3. Jim Yanik

    Jim Yanik Guest

    NiCds like to be USED,not stored. I've had many NiCd packs that lasted
    years when used regularly,but when left unused for long periods,failed
    quickly.Newer NiMH cells have better characteristics in that respect,I
    believe.

    For tools that get used infrequently,it may be better/more practical to use
    corded tools.
     
  4. JM

    JM Guest

    quoting:
    Bad advice by the manufacturer. NiCads slowly cook to death if left on the
    charger for weeks at a time. If this is the case, then your batteries would
    be permantly dead, nothing will bring them back to life. This is not memory,
    it's called "overcharge damage".

    "Memory" happens when a Nicad cell is continually discharged not all the way
    dead before being recharged.

    Memory is completely reversable. Overcharge damage is not.

    Run the drill until it gets slow, then rechagrge. Do that 2 or 3 times, see
    if you notice any improvement. If there's no improvement, then it's got to
    be overcharge damage, then at that time it will be time to buy new batteries.
     
  5. thanks for the followup answers. I thought the chargers had circuitry to
    cut back the charge after charged, and only trickle charge, or go on as
    needed. I guess not.
    mm
     
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