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ThinkPad 600 battery stops charging at 65% (won't fully charge)

Discussion in 'IBM Thinkpad' started by John Navas, Jun 8, 2006.

  1. John Navas

    John Navas Guest

    I've resurrected an old ThinkPad 600 (still a great machine), but now I
    find the old battery (which still works pretty well) won't charge above
    an indicated 65% -- it just sits on charge at that level forever. I've
    run the battery down to nearly flat a couple of times and recharged, but
    the problem persists. I'm guessing the chip in the battery hasn't
    adjusted to the reduced capacity. Anyone know how to fix this?

    I'm running Windows XP Pro SP2 with all the appropriate additional
    drivers and software for the 600, including IBM ThinkPad Battery
    Maximizer and Power Management Features.

    John Navas, Jun 8, 2006
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  2. John Navas

    Ed Guest

    I don't know how old that battery is, but I'd guess its near the end
    of a normally useful life, anyway. Mis-use might easily have shortened
    that lifespan, too.

    If the electrolyte in the cells had just dissapated over the years,
    then perhaps this "chip in the battery" that you mention might have
    adjusted to that .... personally, I didn't know there was a chip in the
    battery that would do that.

    However, in your case is sounds more likely that a cell has reversed
    within the battery which will prevent it from ever reaching the normal

    In any case, the battery is most likely in need of replacement.

    Ed, Jun 8, 2006
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  3. John Navas

    John Navas Guest


    Thanks for the comments and suggestions. However, as I wrote, the old
    battery "still works pretty well" -- in a rundown test yesterday it
    powered the machine with hard disk and display both on for over 2 hours
    -- so there's no issue of mis-use or dissapated electrolyte, much less
    cell reversal. (If a cell was actually reversed, or shorted, the
    battery wouldn't work at all.) There is a chip in the battery -- it's
    an "intelligent" battery -- and it can get out of sync with the real
    condition of the battery.


    The battery pack for the ThinkPad 560, 600, 760, 765 and 770 series
    systems is an intelligent battery. It contains a microprocessor to
    monitor its capacity. Information of remaining battery capacity is
    passed to the system from the battery pack, and the system indicates
    the capacity in 1% steps from 0% to 100% with high accuracy. If the
    indicator appears to be incorrect, it is recommended that you cycle
    the battery (fully charge, then fully discharge) three times. This
    may occur when the battery is over charged or discharged.

    In my case the battery got discharged in long storage, which is
    probably what's confused the chip. I've now done the recommended three
    battery cycles, but still can't get it to report a full charge (at its
    reduced capacity). The chip is also confused at the low end of the
    range -- in the last cycle I got at least 30 minutes of full operation
    after the chip reported the battery to be exhausted.

    As an aside, I suggest you be a bit more careful in the future about
    giving out advice you don't know to be sound -- someone else might have
    followed your advice, and discarded a still good battery. Lithium Ion
    batteries either slowly wear out with use and age, or fail completely.
    Mine has aged somewhat, but isn't in need of replacement.

    Anyone else?
    John Navas, Jun 9, 2006
  4. John Navas

    Ed Guest

    A few comments in reply: Just because the battery "works pretty
    well" does not mean it has not been abused, damaged, or reached near the
    end of its apparently longer than normal life. Congratulations on being
    able to get 2 hours out of it. Still, you mentioned this is an old
    computer, and Lion batteries are only spec'd for a normal life of about 2
    to 3 years. A Thinpad 600 is older than that, isn't it? If treated with
    excessive care, one can get more than that out of the battery, but normal
    aging will deteriorate the battery no matter what.

    My primary exposure to batteries is in the telecommunications
    industry, not computers, so I wasn't aware that there was a monitoring
    chip in the T 600 battery. IBM's procedure to 'reset' the chip might
    have helped in that regard, but deep discharging of LiOn batteries is
    likely to cause problems too. That is a known characteristic weaknes in
    the LiOn battery. If that battery was left in a state of full discharge
    for even a week or two, it is likely permanently damaged. Given that you
    said it was probably in that state for a long period, then it is toast,
    or soon to be toast. Given its age, I still recommend replacement if
    you count on that computer reliability at all. I've spent 35 years
    professionally trying to get the most out of rechargable batteries and my
    experience tells me, given your information, your battery is near the end
    of its already longer than usual life. Then again, I'm willing to budget
    for these expensive items when I know its time to do so. I know there
    are some who can't or won't.

    Ed, Jun 9, 2006
  5. John Navas

    John Navas Guest

    Again, you're reading things into what I wrote that aren't there. This
    isn't the original battery -- I never said that -- it's actually a
    replacement battery that's had relatively light use. I think that would
    have been a more reasonable assumption on your part, not only because of
    what I wrote, but also because the original batteries have probably been
    replaced in most of the 600s still in use.
    I'm familiar with Lithium Ion issues, and this battery hasn't been "deep
    discharged" -- monitoring circuitry ensures that it's just discharged to
    a safe point.
    I only said it had been stored for a long time, not that it was stored
    when discharged. In fact it was fully charged when the machine was put
    into storage, per the IBM recommendation. I was referring to
    self-discharge, which occurs in storage.
    I seriously doubt that. It shows no signs of misuse or damage or of
    otherwise nearing the end of its useful life.
    With all due respect, there is no "reliability "issue -- at most there's
    a reduced capacity issue.
    My own approach is different from yours:

    * I'm quite familiar with the battery design.

    * I know the battery meter issue to be a known problem with the ThinkPad

    * I see no real evidence that this battery is anywhere near the end of
    its useful life.

    * My budget is more than adequate and not a factor.

    * I see no good reason to waste the remaining life of a good battery,
    especially one with as much remaining capacity as this one.

    * I know of a local place where I can get same day pickup of a fresh
    replacement battery if and when I really need it.

    Your approach is different. I respect that. Kindly return the favor,
    instead of being so quick to jump to negative conclusions.
    John Navas, Jun 9, 2006
  6. John Navas

    Ed Guest

    Well then, John, much of my argument is moot, since you tell me that
    this is not the original battery. I apparently misunderstood your
    original post when you said, "I've resurrected an old ThinkPad 600
    (still a great machine), but now I find the old battery (which still
    works pretty well) won't charge above an indicated 65% -- . . . "

    When you said, "old battery" I naturally assumed the original. Sorry.

    As far as discharge goes, it doesn't matter whether or not the
    computer is on or not to get a deep discharge on a battery, ANY battery.
    Internal resistance alone causes current to flow, and this is also the
    case with LiOn batteries. If left stored long enough, that battery will
    self discharge itself to death, which I indicated previously. You didn't
    indicate how long that computer was in storage but I'd say several months
    of storage would be more than enough to cause permanent damage.

    On the other hand, I admit none of my comments are helping you with
    your original problem/question. Sorry. I did a little Google on the
    subject and came up with nothing you haven't already found, except for a
    number of negative discussions on the T 600 battery.

    Good luck. As a side, I want to say that over the past 10 or 15
    years I have enjoyed your website information and was surprised to see it
    still going strong after all these years. Keep it up and thankyou.

    Ed, Jun 10, 2006
  7. John Navas

    John Navas Guest

    Fair enough. I said "old" because it isn't "new" -- it's the battery
    that was in the machine when it was stored, not a new one. Had it been
    the "original" battery, I would have noted that, because then the age
    would be far beyond normal life. This battery is "old," but still less
    than 2 years total, not so old as to be well beyond normal life, and
    stored for less than a year.
    With all due respect, it does matter. It's quite easy to damage a
    battery with deliberate deep discharge, whereas the shelf life of
    charged Lithium Ion Batteries is on the order of 1-2 years. Self
    discharge is about 5-10% per month, and is a result of chemistry, not
    internal resistance.
    Thank you for that, and for trying to help as well.

    Update: The chip seems to be getting more, rather than less, confused,
    and it's possible that I may have to replace the battery for that reason
    alone, even though the cells still have good capacity. [sigh] But I
    haven't given up on it yet.
    John Navas, Jun 10, 2006
  8. John Navas

    JHEM Guest

    John, cover the center two contacts on the battery with something
    non-conductive. The center ones "update" the internal chip and covering them
    and then charging the battery can sometimes reset the chip. The outer two
    contacts (marked + and -) are the ones that provide current to the cells.

    Never done this myself, but I've been told it works.
    JHEM, Jun 10, 2006
  9. John Navas

    John Navas Guest

    Thanks for the reminder. I may have to give that a try. The chip is
    now very confused -- this morning it first reported the battery as dead,
    not able to take a charge. After a power cycle the battery is now
    charging normally (back up to 10% as I write this).
    John Navas, Jun 10, 2006
  10. John Navas

    John Navas Guest

    That last normal charge cycle only got up to an indicated 59% before
    charging indefinitely with no further gauge increase. I'm now trying
    charging with the center two contacts covered.
    John Navas, Jun 11, 2006
  11. John Navas

    John Navas Guest

    SUCCESS: As a result of several discharge-charge cycles, some with the
    center battery pins covered with paper, have now managed to get the
    battery chip back in synch with the battery cells, with the Windows XP
    power meter now showing 100% charge with the battery fully charged.
    Good battery saved. Thanks to those that offered helpful suggestions.
    John Navas, Jun 13, 2006
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