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newbie battery life question

Discussion in 'Laptops' started by Peter H, Dec 6, 2003.

  1. Peter H

    Peter H Guest

    I recently purchased a used Dell Latitude CPx pentium3 which runs win2k.

    Being new to laptops I'm not too knowledgeable about the equipment. There is
    a battery indicator that sits in the system tray and shows the amount of
    time I have left on the battery. It lies, but that's not my primary concern.
    What I'm wondering is how long I can expect the laptop to operate on a fully
    charged battery. It seems to be able to get about 1/2 hour of service out of
    a fully charged battery, which is far less than I was hoping. I had planned
    on using this computer to take notes in classes.

    If I were to purchase a new battery would I have options on the type of
    battery I could get and what would be the max amount of time I could hope
    for with a new battery?


    Peter H
    Peter H, Dec 6, 2003
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  2. Peter H

    Conor Guest

    If its not a mobile processor you're looking at 2hrs tops usually. 1/2
    hr indicates a knackered battery TBH.
    Conor, Dec 6, 2003
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  3. Peter H

    Ian Stirling Guest

    Do some searching on Dells website for the press releases about the launch.
    1/2 hour is too short, and indicates a broken battery (or much less likely,
    Ian Stirling, Dec 6, 2003
  4. While battery life is highly variable, you should get at least 2 hours
    from a new, fully charged battery. If you are only getting 30 minutes,
    something is definitely wrong (almost certainly the battery is bad and
    has lost most of it's capacity).
    Barry Watzman, Dec 6, 2003
  5. Peter H

    Chris Allen Guest

    You have to divide the energy capacity of the battery(ies) by the
    mean power draw of the unit. The battery capacity should be listed
    on the battery in watt hours (WH). Power draw on battery power for
    most laptops is usually in the range of 10-30 watts. Most laptops
    will run in the range of about 1-5 hours on a single, brand-new main

    Age of a battery is important. Lithium-ion batteries will drop to
    80% of original capacity after 1 year at room temperature without
    being used at all. If it *is* used at all, it will drop more. If it
    is subjected to high temperatures, it will drop *a lot* more. The
    main key to lithium-ion longevity is temperature. This is because,
    just like food, lithium-ion batteries degrade through oxidation.
    Keeping a Li-Ion battery in a ziplock bag in the freezer will allow
    it to stay good for years.

    There are a few things you can do to minimize the power draw of
    any particular laptop (to, by extension, maximize the battery life).
    One thing is to use a single RAM stick instead of two, where this
    is feasible. For example, is you are using two 128 MB RAM sticks
    in two slots, you would be able to cut several watts of power draw
    by replacing them with a single 256 MB RAM stick.

    Another thing you can do is turn off unused devices such as (these
    are just suggestions -- of course, if you are using these, or if it
    would be inconvenient to turn them off, then they should be left on):

    * parallel port
    * serial port
    * docking port
    * sound card
    * LAN card
    * wireless card
    * PCMCIA ports

    A third thing you can do is dim the screen to its lowest brightness
    level (laptop users and magazine laptop reviews frequently report
    this helps save many watts).

    Chris Allen, Dec 7, 2003
  6. I disagree with a lot of your post.

    Battery capacity is listed in maH (milliamp hours), not watt-hours.
    It's possible to convert watts to mah, but not everyone knows how to do
    it. [watts = volts x amps ; 1000 mah = 1 amp ]

    If they are properly used, Lithium batteries can last almost a decade
    with virtually no loss of power or capacity at all. I have several 1997
    Toshiba batteries here that are "good as new" and that have been used
    quite a bit, but carefully. The worst killers are heat, overcharging
    (which produces heat) and discharging to extremely low levels (down to
    less than 10%). If you are going to use the laptop on AC almost all of
    the time, REMOVE THE BATTERY (it shouldn't be necessary, but in fact
    extensive reviews on this board suggest that it is). It's definitely
    possible to destroy a $200 lithium battery in one year if you abuse it.

    I totally disagree with the advice about RAM. A single 256 meg stick
    may or may not draw any less than two 128's; indeed it may be the exact
    same components just in a different physical configuration. But, in any
    event, even if it's newer, higher density components with a smaller
    fabrication geometry and less power drain, the power drawn by RAM is
    insignificant in terms of the total power consumption of the entire
    laptop. It's just overwhelmed by the CPU, hard drive and display, among
    other factors.
    Barry Watzman, Dec 7, 2003
  7. Peter H

    Chris Allen Guest

    The Battery University website says batteries should be kept cool down
    to 0 degrees celsius, but not frozen.

    Refrigeration is recommended but freezers must be avoided.

    The site doesn't seem to say why.

    Chris Allen, Dec 11, 2003
  8. Peter H

    Ian Stirling Guest

    Looking at the makers website (sony, panasonic) for the individual cells,
    they are rated down to -20C for storage.
    Ian Stirling, Dec 13, 2003
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