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I know that atleast once or twice a month a full battery drain and then a 100% charge helps increase the battery life and also gives more accurate battery readings.

I was wondering, how frequently is it okay to let it drain as low as possible or to zero?

Like is it okay even if done most of the times(or all the times) or it should not be done more than like say max 5-6 times a month or so??

Thankyou!

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Fully discharging a lithium-ion (or lithium-polymer) battery is generally not advised, actually. It was common for older NiCad batteries, but the chemistry of Li-Ion/Li-Po batteries is rather different. Related questions: When should I start charging my Lithium battery?, Battery Life and First Time Charging on Li-ion Batteries. Myth? –  eldarerathis Nov 19 '12 at 22:19

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once or twice a month a full battery drain and then a 100% charge helps increase the battery life

That is incorrect, a full discharge is never beneficial to LiON battery capacity. The battery life of a LiON battery is dependant mostly on temperature, discharge rate, and age. In fact, low charge state actually is harmful to LiON battery capacity; although modern batteries have circuits that tells the system to shutdown before it became really harmful to the battery, it is best for LiON battery to be plugged in as often as is convenient.

also gives more accurate battery readings.

As for calibrating battery meter by full discharge-recharge, that is partially true. The following is a quote from HP regarding Smart Battery System in their laptops:

Repeated short discharges and recharges cause increasing inaccuracy between the state-of-charge of the battery and the Power Meter readings. Periodically, the battery needs to be calibrated to "relearn" its usable capacity so it can synchronize its charge status with the Power Meter. ... The user simply has to periodically discharge the battery until the 5% capacity alarm is received. The need to perform this procedure will vary with individual use. In general, a Li-Ion battery should be calibrated a minimum of once every 3 months. A battery that is seldom discharged completely should be calibrated about once a month.

and the following is from Battery University:

How often does a battery need calibrating? The answer depends on the application. For practical purposes, a calibration should be done once every three months or after 40 partial cycles. If the portable device applies a periodic deep discharge on its own, no additional calibration will be needed.

The need for calibration comes from the mismatch between the battery's chemistry and the microchip that estimates the battery's state of charge. This mismatch develops over numerous partial discharge, although unlike the memory effect in NiCad battery, it does not affect the battery's actual capacity and is reversible by letting the battery relearn its bottom and top charge state. Do not do calibration too often since deep discharge does permanently harm LiON's actual capacity.

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+1 -- that's some things I considered might be legitimate reasons for "calibration" (which is why I never said "it's useless", but "it's considered useless/a myth by most/many"). Thanks to your answer I know have some sources and good explanation (had problems to put mine into words ;) –  Izzy Nov 20 '12 at 7:08
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thanx a lot...a gr8 answer with reliable sources! cleard all my misconceptions! thanx a lot! –  Nirmik Nov 20 '12 at 13:22

For this question you might want to check with the Wikipedia article on LiIo batteries. Quoting:

  • Avoid deep discharge (depletion) and instead charge more often between uses. The smaller the depth of discharge, the longer the battery will last.
  • Avoid storing the battery in full discharged state. As the battery will self-discharge over time, its voltage will gradually lower, and when it is depleted below the low-voltage threshold (2.4 to 2.9 V/cell, depending on chemistry) it cannot be charged anymore because the protection circuit (a type of electronic fuse) disables it. [...]
  • The rate of degradation of Lithium-ion batteries is strongly temperature-dependent; they degrade much faster if stored or used at higher temperatures and may even be stored in a refrigerator.

The first point already answers your question: You'd better avoid to "deep discharge" your battery. Best is to always keep it on 50% or up, but 20% should already "cry" for a charger. There's no memory effect or the like, so no need for that.

You might refer to the so-called "battery calibration" -- which today is called a myth by most, as explained by Google developer Dianne Hackborne.

If you think a "full charging cycle" (that is what you describe) might be useful from time to time (also see Lie Ryan's answer for this), make the interval between them as large as possible. IMHO multiple times a month is much too much -- once every 3 month should be enough. In that timeframe it might even accidentally happen you nearly "run out of juice" unwittingly, so you can use that "chance".

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Dianne debunked the myth of doing battery calibration by deleting batterystats.bin; in her post, she is not addressing calibrating battery by doing a full discharge-recharge cycle. In particular, she does not claim that all kinds of battery calibration is a myth. –  Lie Ryan Nov 20 '12 at 1:40
    
@LieRyan you're absolutely correct -- though that's what most people think (especially those not having read her post personally, which I did yesterday and got my surprise). First time I read about the real need for any calibration claimed by the producer is right now in your answer, quoting HP and Battery University. Thanks a lot for those sources! –  Izzy Nov 20 '12 at 7:04
    
Thanx a lot! your answer is equally well writn...i had to choose...i randomly chose...sorry! But many thanx! gr8 answer ;) +infinity –  Nirmik Nov 20 '12 at 13:21
    
Lie quoted the better sources, so he earned it :) No prob whatsoever to me, as you can see in my comments. I was even proud to see "my theory" with the 3 months approved from "higher up" xD –  Izzy Nov 20 '12 at 14:10
    
Does that mean connect the battery to the charger when not in use? –  Extreme Coders Jul 6 at 5:38

Lithium batteries were invented to avoid the issue of the 80% charge on the balance of power.... Charging at anytime has NO effect on the battery... Older batteries could only charge 80% ow the empty cycle...but NOT true with Lithium ion or polymer batteries... Charge anytime, any amount...no problem

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