What the heck is going on with my new 9 cell battery...

Discussion in 'Lenovo' started by Blue Diamond, May 15, 2009.

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  1. Blue Diamond

    Blue Diamond Notebook Evangelist

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    soon as i stuck it in right out of the seal, i charged it till 100%, then disconnected the AC power and played games until it reached 5%... then i recharged again, the power manager considered that one cycle.... my design capacity on this is 84.24 Wh... after the first cycle, max capacity suddenly dropped to 79.45Wh. is this considered a faulty battery? or is this normal in some way?
     
  2. idq000

    idq000 Notebook Deity

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    Nope, what happened is completely normal.

    You completed one "deep cycle" of the battery. Let's discuss the chemistry behind the reason why this happened. First, you charged the battery so lithium ions are discharged into the anode. Second, you rapidly drained the battery (since you were gaming, which increases your draining rate) and quickly collected on the cathode. By deriving and looking at the half-reactions, one can see that some of the product formed is Lithium Oxide, which, once formed, is irreversible and contributes to the lowering of the capacity in your battery. Since you did a charge, then a fairly rapid drain, and then charged it again (I'm going to guess at elevated temps) and by Le Chatlier's Principle, the reaction will favor the products more than the reactants. Also, you will always lose some charge (more if you continually do this deep cycling) since NO process (in this REAL world) is ever 100% efficient, so it will never be at the original capacity once you use it. Remember next time to use not as much battery as you did this time, since the more you do this, the more the products will build up and your battery will prematurely die.
     
  3. Blue Diamond

    Blue Diamond Notebook Evangelist

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    so the rapid drain is what caused the sudden drop in max capacity?
     
  4. Persnickety

    Persnickety Notebook Evangelist

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    It shouldn't have been such a big difference, no matter what, on just a single fast discharge. Li-Ions are built to discharge fast, and you going to 5 % isn't a complete discharge as it is. No, it's propably the meter that is off (or were off). I'd recalibrate the battery and then see.
     
  5. Blue Diamond

    Blue Diamond Notebook Evangelist

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    you mean discharge it till 0% and then recharge?
     
  6. surfasb

    surfasb Titles Shmm-itles

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    The meter isn't 100% accurate you know..... just like the power meter in windows.
     
  7. mrjohn

    mrjohn Notebook Consultant

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    If you want to keep the battery alive for as long as possible use the charging thresholds in power manager, I've got mine set to charge @ below 35% and stop at 55%. If I need to go somewhere I charge to about 95%. Being full or empty increases battery wear.
     
  8. martinmach

    martinmach Notebook Evangelist

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    my battery shows 80.79 Wh after 6 months. i have been charging with 65 % to 95 thresholds
     
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