linux-kernel - Re: Low-Level and Long-Term Battery Control

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Message-ID: <q2p72dbd3151004151642p9c0b8a14yc9de251b134aec08@mail.gmail.com>
Date:	Thu, 15 Apr 2010 16:42:56 -0700
From:	David Rees <drees76@...il.com>
To:	Pavel Machek <pavel@....cz>
Cc:	Mohamed Ikbel Boulabiar <boulabiar@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: Low-Level and Long-Term Battery Control

On Thu, Apr 15, 2010 at 11:02 AM, Pavel Machek <pavel@....cz> wrote:
>> For Laptops, it is better to extract the battery from the Laptop when
>> the computer will be on power for a long period.
>> I ask if the kernel can do such control without the user intention and
>> in an automatic way.
>>
>> Some BIOS provide to the user to select whether to block the battery
>> charging to 50% to make it stand for more time.
>
> Where have you seen that?

I do recall that some older ThinkPads had a utility that would let you
determine what "empty" and "full" was by setting artificial limits.
It's well known that by keeping batteries from being fully
charged/discharged can significantly extend it's useful life although
you will suffer from shorter run-times.  How sensitive a battery is to
this depends on it's exact chemistry, but all are affected by this to
some degree.

For example, by keeping your battery from charging above 85% and below
15% can increase the number of charge/discharge cycles a large amount
often on the order of 5-10 times more charge/discharge cycles - much
more than the 30% reduction in total capacity.  Limiting to 25-75%
will help even more.

-Dave
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