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Thread: Weird laptop battery behavior.

  1. #1

    Default Weird laptop battery behavior.

    Hey guys, I bought a used laptop the Portege 2000. The battery is a Li-ion polymer battery that is really really thin and small. The laptop reports that the capacity is still 89% of the original but that information is irrelevant. The battery drains down to about 60 - 50% and then just dips do to 3% and stays there for about 10 minutes. Then the computer just turns off when there is nothing left. I configured it so that it would drain all the way down so I could calibrate the battery. Did it twice and it still exhibits the same behavior. I don't understand what the drop from about 50% to 3% is. Could someone help me. And why is the battery not correcting for that and calibrating correctly?

    Sorry could you delete this ... wrong section.
    Last edited by johnny13oi; 04-25-2007 at 08:17 PM. Reason: Sorry wrong section

  2. #2
    *Flashaholic* Illum's Avatar
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    Default Re: Weird laptop battery behavior.

    your battery is considered dead, as in the inability to hold a charge, its not weird, but typical of most laptop batteries after 3-5 years of normal use

    If you bought it new, might want to inform the seller of this, because this is atypical and may be considered a defect or worse...

    believe it or not, the battery meter of laptops after the first year or so loses the ability to accurately measure battery condition because of chemical changes within the cell itself causing the apparent miscaliberation

    I should know...I've been through three laptops

    usually its best to replace the battery rather than taking it apart and change the 18650s inside it

  3. #3

    Default Re: Weird laptop battery behavior.

    Thanks for the info. The battery is actually a Li-ion Polymer battery and doesn't contain 18650s inside. The battery is really thin. About the thickness of a pen. The battery does last for about an hour but the jump from about 50 to 3 is annoying.

  4. #4
    *Flashaholic* Illum's Avatar
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    Default Re: Weird laptop battery behavior.

    sorry, over read the Li-Po part

    it is annoying I know, my toshiba [A15-S129]'s 6 celled Li-ion does the same, only my meter goes from 100-95 immediately after unplugging, then for the next 15 seconds the low battery alarm clicks then around 20

    the reason why I never tossed it out was the fact I never used it on mobile very much...I mean jeez...a 15" laptop with a 2.4 GHz celeron's rather underpowered with the 6 cell, the laptop battery to me is just a functioning UPS for my system for those brownouts.

  5. #5

    Default Re: Weird laptop battery behavior.

    oh I use this laptop for the only purpose as to use during class which would require for it to be mobile. The laptop was used and was cheap as I needed something to just type on. But now I am just trying to find out how to get a new battery for cheap or possibly rebuilding it or any other action as I am a college student and funds are .. low.

  6. #6
    *Flashaholic*
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    Default Re: Weird laptop battery behavior.

    the 50% to 3% might be due to how the battery pack "info" is used, or if "info" is being recieved from the pack also.

    i have a PDA that uses Li-poly, and it had TWO methods that it could read the "capacity left" one was using the calibrateable info lithium chip in the battery, and the other was Strictally voltage based.
    the info part would read a linear declining progression.
    the voltage only method would read high for a long time, then after 50% (about) it takes a dive.

    the WAY i discovered that it could use both methods, is:
    when i increased the total capacity of the cells, the original "info" curcuit was unable to calculate the higher miliamps of the increased capacity, sooo i discombooberated the "info" data link, and the Pda reverted to just reading the voltage.

    This same thing can occur if you purchaced a cheap, or similar but not same , replacement battery that does not output "info" data.
    or (for example) if you purchaced some "extended" capacity battery that any internal workings of the laptop itself no longer can calculate the "info"

    Glossary
    * by "info" i mean a serial port type data link to the battery curcuit chip.

    if the battery still does the TIME, within the power consumption (more cpu is less time) of what is expected, MABEY its just a info issue and not a reduced capacity at all?
    Last edited by VidPro; 04-25-2007 at 09:27 PM.

  7. #7

    Default Re: Weird laptop battery behavior.

    Thanks for the info. I thought that laptops with Li-ions used the method where they read from the info circuit of the battery and thats how they displayed the life remaining. The battery I have is the OEM Toshiba battery that the laptop comes with so it isn't a cheap replacement battery. The laptop battery has multiple pins so I would believe that the battery outputs some kind of information about the life of the battery.

  8. #8

    Default Re: Weird laptop battery behavior.

    In most laptops, the battery charge indicator signal (% charge) comes form the battery itself, not the laptop, so a bad battery would explain the unusual behavior. Also, unlike NiMHs, LiIon's don't like to be discharged (below 30% or so). So if you do get a new battery, don't let the laptop sit on the shelf unplugged for too long, because LiIons will gradually discharge all by themselves over time even if you don't draw any current.

  9. #9

    Default Re: Weird laptop battery behavior.

    Any cheap recommendations on where to obtain li-ion polymer cells or cheap laptop batteries? The ones I find on ebay are about $60 for ones that say compatible which I assume means generic batteries. Any for cheaper?

  10. #10
    Flashaholic* Trashman's Avatar
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    Default Re: Weird laptop battery behavior.

    Quote Originally Posted by Illum_the_nation

    believe it or not, the battery meter of laptops after the first year or so loses the ability to accurately measure battery condition because of chemical changes within the cell itself causing the apparent miscaliberation
    Somewhere on the net, I read that to keep the battery meter functioning correctly, the battery should be fully discharged (well, not FULLY, but up to the point where the computer tells you to plug the laptop in or it'll shut off) once a month. I was doing that, but I've forgotten about it. I leave it plugged in all the time, these days, anyway.

  11. #11
    Flashaholic* koala's Avatar
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    Default Re: Weird laptop battery behavior.

    You need to recalibrate the "intelligent" battery monitor built in to your battery pack. Most laptop BIOS has an option for battery recalibration otherwise it is software side.
    Arc4+ mods/repair. LED drop in for SF E-Series. Onion Rings for SF A2.

  12. #12

    Default Re: Weird laptop battery behavior.

    Any tips on how to do this? I dont see any setting for battery recalibration inside of the bios.

  13. #13
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    Default Re: Weird laptop battery behavior.

    If it quickly drops to empty, most likely means one of the cells is too weak and has already reached 3 volt. Smart batteries monitor all cells voltages and dont let that happen to any of them. They seem to send a shut down command to the laptop, i have test discharged an old Dell battery pack and got like 1.2 Ah out of it, of course only monitoring the total voltage (4 cells in series = 12volt cutoff), so probably drained a cell too much, but this shows that other cells still have power. The same battery in laptop only lasts for 10 minutes, which is hardly 1.2Ahrs, since the laptop sucks about 1.5 A. Best use for dead battery packs is use the cells for flashlights i have built a discharge rig to test capacity of 18650s, very nice and handy.

    some pics are here http://www.received21.de/cgi-bin/r21de/thmb.cgi?ct=00;

  14. #14

    Default Re: Weird laptop battery behavior.

    The cells inside the battery are of the polymer type, cant use them in flashlights =/. They're like thin little plates.

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