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10 years ago when I was doing hardware support it was best practice to fully drain a laptop battery prior to recharging in order to maximize its life. Is this still the case or can a battery now be recharged at any point without worrying about shortening the lifespan?

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This might be relevant as well: lifehacker.com.au/2009/10/… –  AnC Oct 30 '09 at 20:27

8 Answers 8

up vote 17 down vote accepted

NiCd and Nickel Hydride batteries need occasional deep discharging. Lithium batteries do not suffer from the same issue - and deep discharging can damage them. This article discusses the subject in more depth.

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batteryuniversity.com is not a reliable source. –  Jamie Hanrahan Aug 8 '14 at 20:25

I believe there's not really "battery memory" anymore with modern batteries, but it's a good idea to run down completely one time from a full charge to calibrate the "remaining time" left on most laptops. I've done this on both Mac and Windows laptops and it helps.

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Nope, although every 10-20 charges, it is best to in order to calibrate your battery (otherwise you may see it saying 2 hours left and then going flat after 20 minutes!)

You are referring to the "memory effect". Typically, Lithium Ion batteries (most modern gadgets use these) do not get affected by this.

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Lithium ions seem to have different issues, more to do with how far you drain them and how you store them http://en.wikipedia.org/wiki/Liion#Guidelines%5Ffor%5Fprolonging%5Flithium-ion%5Fbattery%5Flife

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If your laptop has a lithium ion (li-ion) battery, it does not retain a memory. Meaning you can charge them when ever you feel like it. At 10% or 90% it doesn't matter. The downside to li-ion batteries is they do not last that long. After a few hundred charges and prolonged use they do not hold a charge as well as when they were new.

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For lithium-ion, it is actually now considered bad practice to completely drain the battery before recharging. NiCd and NiMH batteries need this to be done to minimize their so called "memory effect" - not so for Lithium Ion. In fact, it will actually be harmful for Li-Ion batteries.

I quote you this paragraph from this link

A lithium-ion battery provides 300-500 discharge/charge cycles. The battery prefers a partial rather than a full discharge. Frequent full discharges should be avoided when possible. Instead, charge the battery more often or use a larger battery. There is no concern of memory when applying unscheduled charges.

There are many other sources online that support this statement, but I know this from my long-time exposure to battery conditioning due to certain hobbies (e.g flashlights).

From Wikipedia's entry of Lithium Ion batteries :

Lithium-ion batteries should never be depleted below their minimum voltage (2.4 to 2.8 V/cell, depending on chemistry). If a lithium-ion battery is stored with too low a charge, there is a risk that the charge will drop below the low-voltage threshold, resulting in an unrecoverable dead battery.

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I use a Dell Inspiron 1525 laptop. Recently, when my battery conked out, the reseller told me that I need to let the battery drain out once a month. I suppose he was just dishing out a defunct piece of advice.

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No. Lithium-ion batteries are not subject to the memory effect, and repeated full discharges will significantly reduce the life of the battery.

However, "smart" batteries, which keep track of the charge level to determine the percentage of battery life remaining, may gradually lose track of the full charge and discharge points over many partial charge-discharge cycles, causing them to report incorrect charge levels. For these batteries, fully charging and discharging them can recalibrate the battery so that it reports the correct charge level. This generally only needs to be done once every 3-6 months of use, depending on how much the battery is used. More information on battery calibration can be found in this Battery University lesson.

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