Should I drain the battery?

Discussion in 'Alienware M11x' started by Bily42, Aug 28, 2010.

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  1. Bily42

    Bily42 Notebook Consultant

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    New M11XR2 owner here. I've been letting the battery drain to 10% and just one time tried to drain it down below that to about 5%.
    What is best for creating longevity for the battery and maintaining a long 5 1/2 to 6 hour battery life on the m11xr2?
    Does anybody really know?
     
  2. LingJ

    LingJ Notebook Geek

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    For the M11x's battery (which is a lithium ion I believe) should never be fully discharged. Also keeping it on a/c power all the time is perfectly fine.
     
  3. corwinicre

    corwinicre Notebook Deity

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    It's true ideally the battery should never be brought low because it reduces the capacity, but it is usually recommended every 30 or so discharges to run it out of battery because partial discharges cause the capacity reading to become less accurate, and that is fixed by depleting the battery completely. Doing it that infrequently won't affect noticeably the capacity.
     
  4. silicondrifter82

    silicondrifter82 Notebook Enthusiast

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    fully discharge only applies to lead acid batteries and ni-cad. the reason is to establish charge memory of the electrolytes of the battery cells.
     
  5. Bily42

    Bily42 Notebook Consultant

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    Thanks for the info.

    I noticed after I drained to 5%, I got less battery life and the Windows remaining battery life went all to h*ll. It now sometimes says it has 131 hour and 10 remaining or switches within a few minutes from 3 hours remaining to 5 hours remaining.
     
  6. Tedster59

    Tedster59 Notebook Consultant

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    I did a full discharge, and my batterybar reading on battery capacity dropped by 2k mWh.
     
  7. kent1146

    kent1146 Notebook Prophet

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    A Li-ion battery should ideally never be discharged that low. LiIon batteries are happiest at 40% charge, stored in a dark, cool, dry place. Heavy charge/discharge cycles and heat are the two worst enemies of LiIon batteries.

    If you absolutely want the longest possible life on the battery, then keep it at 40% capacity. Then turn off the charging capability by going into the BIOS, and setting "Charger Behavior" setting to Disabled. When your laptop is plugged into the AC power adapter, it will run off of power, but not charge the battery.

    When you are about to go on a trip where you know you will need battery power, then go into BIOS, change the setting back, and charge your battery to 100% before you leave.

    Li-ion batteries should typically never be fully discharged. However, it is good to fully discharge them once every 30 or 40 power cycles to calibrate the battery meter.

    And keeping it on A/C power all the time is the worst possible thing you can do to your battery. What you're essentially doing is constantly charging your battery every time there is even the slightest discharge - and batteries will slightly discharge just by sitting there. If you keep your battery on A/C power all the time, you can expect your battery capacity to be around 50% - 75% of max capacity after about 1.5 to 2.0 years.


    It is good to fully discharge Li-ion batteries once every 30 or 40 power cycles to calibrate the battery meter. You are correct that it has nothing to do with the Li-ion battery itself. You do this for the battery meter, that detects remaining charge capacity, and determines how much to charge the battery when it needs charging.

    The way that Windows battery meter works is that it estimates the remaining battery life based on your current level of power draw. And it updates that remaining power measurement once every 60 seconds or so.

    So, when you're bouncing back-and-forth between 3-5 hours remaining because in one moment, you are doing something intensive on your laptop that drains a lot of power. You would typically get 3 hours of life if you continued doing that. The next moment, you're doing something less intensive, and draw less power. You would typically get 5 hours of life if you continued doing that.

    The readings are spot readings at a given moment. They are not average-over-time readings, so it is perfectly normal for the reading to bounce back and forth as you're doing many different things with your laptop.
     
  8. DankDarko

    DankDarko Notebook Enthusiast

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    I may be wrong, and you may rebute, but I believe this to be false. The way I understand it, once plugged in, the battery charges up to nearly full (between98%-99%) once it hits this "full" mark, the M11 mearly runs off the A/C forgoing battery charging all together. While everything you said is correct typically, I believe this to be a feature of the M11x.
     
  9. kent1146

    kent1146 Notebook Prophet

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    You are correct that a device that has a Li-ion battery will charge to full, then stop charging. All devices with a Li-ion battery will do this. It is not unique to the M11x.

    However, a fully charged Li-Ion battery will slowly lose charge over time, even if it is just sitting there running off of AC power. When that happens, the charging circuit will kick in, and fill the battery back up to 100% charge.

    This is one of the worst things you can do for the battery. You end up charging the battery relatively frequently this way because of the trickling loss of battery power, you keep the battery at 100% (which Li-8on batteries do not like to be at), and you increase the heat applied to the battery. Over time, a Li-Ion battery that has been treated thos way will only store 50%-75% of its original charge after about 18 to 24 months. The way to avoid this in most laptops is to remove the battery when you are plugged into AC. On the M11x, you have the option to disable the batter charging behavior in the BIOS.
     
  10. BatBoy

    BatBoy Notebook Nobel Laureate

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    FWIW, I never remove the battery from my laptops. My 17x is now a year old and almost always plugged in 24x7 and on the rare occasion I do go mobile with it, I have not noticed any reduced batt time. :)

    Its not going to drain while plugged in. Your batt is under warranty for a year. Don't worry about it. IMO of course :)

    As a couple of other posts mentioned, its the # of complete discharges which will kill your batt. I learned this lesson with my Dell E1705. As I understand it, after about 300 complete drain/charge cycles you are dead in the water.
     
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