How does Windows 8 show the 20% lost battery capacity ?

Discussion in 'Windows 8 Help and Support' started by Ruka, Aug 25, 2014.

  1. Ruka

    Ruka New Member

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    Hello,

    As a student I had quite a lot of trouble with my previous laptop's battery. It had an autonomy of 4h in the beginning, but one day, while it still had 50%, it suddenly dropped to zero for some reason, and after that incident the battery has never exceeded 50% charge again. So I had to buy another one, but this one also dropped to 2h autonomy after some months, although it still showed 100% charge.

    I now have a new laptop, an Asus T300LA, that I chose for its 8h autonomy. As I really wanted to take care of the battery, I searched on the internet how to deal with a li-ion, and learned that I had to drop the charge from 100% to 5% at first use, but should never let it go below 5% as it would permanently lose 20% of its capacity at once.
    But during the process I was too scared that the charge level shown by Windows would be false and while it would indicate 5% it would actually be less, so I plugged the laptop at 8%; and I was indeed right, as the battery level suddenly switched to 5% when I did so !

    Basically I am fearing the infamous 20% battery damage occured without my knowing since the battery level indicated by Windows can't be trusted. The problem is, I don't know how to check it; with my previous laptop (Windows 7), on one battery the damage wasn't shown and it would still indicate 100% charge when filled, whereas on the other one the damage was clearly noticeable as the battery level would never indicate more than 50% even when filled up.

    How can I verify if my battery is pristine or not ? If it indeed lost 20% of its capacity, should Windows 8 indicate a completely filled charge as 100% or 80% ?
    Also, with maximum screen brightness Windows tells me this: "your current brightness setting might reduce battery life". What does it mean by "battery life" ? The current charge length or the whole time I can use the battery before it's good for junk ?
     
  2. ussnorway

    ussnorway Windows Forum Team
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    1. Windows (all) uses default one size fits all protocols for power display and they are not that accurate.

    2. Ime Best practice is to drain the battery down occasionally on models where the battery can't be physically removed from the laptop.

    3. In this case battery life is how quickly the laptop will drain its battery and require power from an outlet.
     
  3. Ruka

    Ruka New Member

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    Thank you for answering,

    I have noticed that the power display is not accurate, but I need to understand how it works in order to know the state of my battery.

    If the Li-ion battery has really been damaged by 20% of its capacity, will WIndows display 80% or 100% for a full charge ?
     
  4. ussnorway

    ussnorway Windows Forum Team
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    I assume it would state 80% but have never encountered this problem on any of the laptops under my care.
     
  5. Ruka

    Ruka New Member

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