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

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Message-ID: <20100416041509.GB1552@elf.ucw.cz>
Date:	Fri, 16 Apr 2010 06:15:09 +0200
From:	Pavel Machek <pavel@....cz>
To:	David Rees <drees76@...il.com>
Cc:	Mohamed Ikbel Boulabiar <boulabiar@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: Low-Level and Long-Term Battery Control

On Thu 2010-04-15 16:42:56, David Rees wrote:
> 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

>From charging below 15%?

> 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.

I believe I've seen "don't charge above 85%", but "don't charge above
50%" is quite excessive...

Anyway, this is done by smartbattery, not by OS.
									Pavel

-- 
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