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That Windows 7 battery thing

  • 20-04-2010 05:13PM
    #1
    Dartz
    Registered Users, Registered Users 2 Posts: 4,420 ✭✭✭


    A little imperical, but I can confirm it.

    I dual boot Windows 7 and Xubuntu Linux. I drained the battery on Windows, right until 0% and powered off. Got home, fired up Linux, and found that for some reason battery capacity had dropped from about 1500mWh, to 1200mWh.

    So I let it charge for a little bit, and then set is discharging.

    The battery meter has been sitting at 56mWh for the last 15 minutes or so. It seems that Windows 7 does something to the battery's reporting software... it's extremely conservative or I don't know what.

    Being short, because I'm running on battery still, and waiting for it to die.


Comments

  • #2
    Overheal
    Registered Users, Registered Users 2 Posts: 86,729 ✭✭✭✭Overheal


    ?


  • #3
    Dartz
    Registered Users, Registered Users 2 Posts: 4,420 ✭✭✭Dartz


    Overheal wrote: »
    ?

    http://arstechnica.com/microsoft/news/2010/02/microsoft-looking-into-windows-7-battery-life-failures.ars

    A while back, there was some controversy over Windows 7 either misreporting, or causing a massive decrease in battery life. I think there was a topic here on it, but didn't find it.

    Anyway, I was able to actually catch it doing it.

    I discharged the battery on Windows 7, to 0%. Then booted to Linux. It only charged to 1200mwh, rather than the more usual 1500mWh. (Old battery)

    So I discharged it again. The battery ran for about 5-10 minutes on 0%, before I shut it down. Rebooting, it's recharging back to 1500mWh again.

    So, it seems that something Windows 7 is doing calculating battery charge is causing a glitch in the battery's self reporting tool. For some reason it's being a lot more conservative reporting it's charge level. The level it reports is already pretty conservative.


  • #4
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 94,377 Mod ✭✭✭✭Capt'n Midnight


    in linux try

    apci -b -i

    this will list the design capacity of the battery and the what the last full charge was. (there is a little microchip in the battery to handle such stuff)


    If you do a few complete charge/discharge cycles the the SOFTWARE will learn the capacity of the battery and set it as 100%. This process will NOT increase the capacity of the battery the mAH will NOT go up. All it will do is align 100% to the reduced capacity of the battery.


  • #5
    astrofool
    Registered Users, Registered Users 2 Posts: 17,329 ✭✭✭✭astrofool


    You can damage Li-Ion batteries by fully discharging them, they have a circuit to protect themselves that keeps a little charge, but if you constantly turn on a device at 0%, you can reduce the battery capacity for further charges.

    The windows issues in the article above are more due to Win7 using more power than it should be, reducing battery life, rather than physically damaging the battery and reducing it's capacity.


  • #6
    [Deleted User]
    Posts: 0 ✭ [Deleted User]


    I don't for one second believe that Windows 7 is "breaking" batteries. It's a case of people shooting the messenger, the problem was already there.


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  • #7
    Dartz
    Registered Users, Registered Users 2 Posts: 4,420 ✭✭✭Dartz


    It's not breaking it... that's not what I mean. For some reason, it's causing the battery to be more conservative reporting it's power. I cycled it a few times in Linux, and it held at around 1500...

    It's just an odd thing I noticed..


  • #8
    [Deleted User]
    Posts: 0 ✭ [Deleted User]


    Nah it's nothing against you personally, just I heard there's a group trying to file a class action lawsuit against Microsoft for "writing corrupt values to their batteries and causing them to fail."


  • #9
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 94,377 Mod ✭✭✭✭Capt'n Midnight


    Karsini wrote: »
    Nah it's nothing against you personally, just I heard there's a group trying to file a class action lawsuit against Microsoft for "writing corrupt values to their batteries and causing them to fail."
    WTF ?


    The EULA limits damages to $5
    Let's say it degrades battery life by 10% - yip that's $5
    Batteries are consumables, some printer consumables will out last batteries in low use printers , projector bulbs are consumables
    And on at least one series of notebooks its the laptop BIOS that reports the wrong design capacity of the battery

    Storm in a tea cup really.

    Lawyers will make a lot of money

    Joe public will be lucky to get a few vouchers for either microsoft products or the affect brand of laptop , a lock in mechanism if you like.



    Looked at the battery spec a while back , and I don't remember it allowing the OS to WRITE to the microcontroller in the battery.


  • #10
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 94,377 Mod ✭✭✭✭Capt'n Midnight


    http://www.laptop-junction.com/toast/content/w7-battery-trouble-consider-replacing-your-battery

    more info , not all the info at every level is 100% accurate and a battery recalibration involves a full charge/discharge cycle and all cycles age the battery slightly
    Laptop-Battery-Life-Windows-7-consider-replacing-your-battery.jpg


  • #11
    Dartz
    Registered Users, Registered Users 2 Posts: 4,420 ✭✭✭Dartz


    Maybe it is just a difference in the system reporting. It's a weird one though, and an old battery.

    Recalibrating it did sort-of work... it holds steady at 1500 now.


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