brad longo wrote:
As I'm sure most of you know, leaving your laptop plugged in and
charging with a full battery charge is harmful for the battery. I have
been trying to see if Fedora's power management tool has something built
in so that when the battery reaches full charge, it will then discharge
to lets say around 95% before beginning to charge again. Friends of
mine with the same laptop use such measures except they are running
windows. However, based on the fact I did not see any documentation
about this, and that my battery charge does not appear to fluctuate at
all once it becomes fully charged (according to the statistics), I'm
guessing no such thing exists in Fedora. Does anyone have any
information as to whether this safety feature exists in Fedora, or
whether some other measures exist instead? Basically I'm just wondering
if I need to periodically unplug my laptop to preserve the lifespan of
the battery, which would be annoying. Also if this is not a feature is
anyone working on developing something like this for Fedora?


brad most all newish laptops use lithium ion batteries, these use a
CC/CV charging routine so leaving the power attached when the battery is
full will do no damage ;-)


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2009/2/17 phil
brad most all newish laptops use lithium ion batteries, these use a CC/CV charging routine so leaving the power attached when the battery is full will do no damage ;-)
Sorry for the off-topic, but is there any damage in taking or inserting the battery while the laptop is turned on (and plugged in)?

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Benjamín Valero Espinosa wrote:

2009/2/17 phil

brad most all newish laptops use lithium ion batteries, these use a
CC/CV charging routine so leaving the power attached when the
battery is full will do no damage ;-)


Sorry for the off-topic, but is there any damage in taking or inserting
the battery while the laptop is turned on (and plugged in)?


apart from possible arcing damage to the connectors no, i also fly rc
helicopters and we connect and we have to disconnect our li-po's all the
time while on the charger :-)


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Matthew Garrett wrote:
> On Mon, Feb 16, 2009 at 07:02:52PM -0500, brad longo wrote:

> Charging of the battery is generally under firmware rather than software
> control. Laptops will typically stop charging at 100%, at which point
> the battery will slowly self-discharge. When the battery hits some
> threshold (typically somewhere between 95% and 97%) the firmware will
> start charging again.
>
> What you're talking about is presumably an interface to modify that
> threshold. This is device specific. The tp_smapi driver (which is not in
> the kernel for exceedingly dull reasons) allows this to be configured on
> Thinkpads. I don't believe that we know how to on any other systems.

I have been running tp_smapi locally for quite some time to reduce the
number of charge cycles on my battery and thus its lifetime.

Given that kernel modules are a no-go in Fedora and I remember having
read somewhere that most of the code is to be expected to go into 2.6.29
or something similar, I have not published my packages until now.

However, someone still might find them useful:

http://ndim.fedorapeople.org/packages/tp_smapi-kmod/
http://ndim.fedorapeople.org/packages/tp_smapi/
or
git://fedorapeople.org/~ndim/tp_smapi-kmod-package.git
git://fedorapeople.org/~ndim/tp_smapi-package.git

These tp_smapi* packages require the rpmfusion akmod stuff.

The user interface is a file in /etc/sysconfig with the two threshold
values. I use 40% as start-charging threshold and 80% as stop-charging
threshold. Occasionally when I know I need more capacity on the road, I
manually force it to start charging and charge higher.

Eventually, I'd like to see that functionality in Fedora with a nice
user interface, but right now it works for me, so I can live with that.

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On Tue, 2009-02-17 at 02:32 +0000, Matthew Garrett wrote:
> On Mon, Feb 16, 2009 at 07:02:52PM -0500, brad longo wrote:
> > As I'm sure most of you know, leaving your laptop plugged in and
> > charging with a full battery charge is harmful for the battery. I have
> > been trying to see if Fedora's power management tool has something built
> > in so that when the battery reaches full charge, it will then discharge
> > to lets say around 95% before beginning to charge again. Friends of
> > mine with the same laptop use such measures except they are running
> > windows. However, based on the fact I did not see any documentation
> > about this, and that my battery charge does not appear to fluctuate at
> > all once it becomes fully charged (according to the statistics), I'm
> > guessing no such thing exists in Fedora. Does anyone have any
> > information as to whether this safety feature exists in Fedora, or
> > whether some other measures exist instead? Basically I'm just wondering
> > if I need to periodically unplug my laptop to preserve the lifespan of
> > the battery, which would be annoying. Also if this is not a feature is
> > anyone working on developing something like this for Fedora?
>
> Charging of the battery is generally under firmware rather than software
> control. Laptops will typically stop charging at 100%, at which point
> the battery will slowly self-discharge. When the battery hits some
> threshold (typically somewhere between 95% and 97%) the firmware will
> start charging again.
>
> What you're talking about is presumably an interface to modify that
> threshold. This is device specific. The tp_smapi driver (which is not in
> the kernel for exceedingly dull reasons) allows this to be configured on
> Thinkpads. I don't believe that we know how to on any other systems.

My dual-boot ThinkPad T61 has a Windows power utility that sets the
level at which charging commences. A recent update of that utility
reset the level to 85%. So what happens is that the slow discharge when
suspended or used briefly on battery doesn't result in a recharge until
the level has dropped below 85%. The utility suggests that this
lengthens battery life as compared to, say a 95% or 97% threshold. I
guess the point is mainly to reduce the frequency of discharge/charge
cycles.
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mjs AT clemson DOT edu
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Hans Ulrich Niedermann wrote:
> I have been running tp_smapi locally for quite some time to reduce the
> number of charge cycles on my battery and thus its lifetime.

I think you mean "and thus increase its lifetime". ;-)

Kevin Kofler

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On Tue, 2009-02-17 at 20:19 +0000, Matthew Saltzman wrote:
> My dual-boot ThinkPad T61 has a Windows power utility that sets the
> level at which charging commences. A recent update of that utility
> reset the level to 85%. So what happens is that the slow discharge when
> suspended or used briefly on battery doesn't result in a recharge until
> the level has dropped below 85%. The utility suggests that this
> lengthens battery life as compared to, say a 95% or 97% threshold. I
> guess the point is mainly to reduce the frequency of discharge/charge
> cycles.

Hay guys there's this thing called Wikipedia:

http://en.wikipedia.org/wiki/Lithium_ion_battery#Storage_temperature_and_charge

Optimal storage charge for a Li-Ion is %40. Also, heat causes Li-Ion
batteries to degenerate much faster, so if you're really worried about
preserving your battery, don't leave it in the laptop while it's
running. Yet another argument for less power usage. Less power, less
heat, longer battery service life. Fewer toxic batteries going in to the
land fill if you like that angle.
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Kevin Kofler wrote:
> Hans Ulrich Niedermann wrote:
>> I have been running tp_smapi locally for quite some time to reduce the
>> number of charge cycles on my battery and thus its lifetime.
>
> I think you mean "and thus increase its lifetime". ;-)

Affirmative.

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On Wed, 2009-02-18 at 01:36 -0600, Callum Lerwick wrote:
> On Tue, 2009-02-17 at 20:19 +0000, Matthew Saltzman wrote:
> > My dual-boot ThinkPad T61 has a Windows power utility that sets the
> > level at which charging commences. A recent update of that utility
> > reset the level to 85%. So what happens is that the slow discharge when
> > suspended or used briefly on battery doesn't result in a recharge until
> > the level has dropped below 85%. The utility suggests that this
> > lengthens battery life as compared to, say a 95% or 97% threshold. I
> > guess the point is mainly to reduce the frequency of discharge/charge
> > cycles.
>
> Hay guys there's this thing called Wikipedia:

...which you usually use for quoting, unsupported, as a reliable
reference on anything.
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>>>>> "AW" == Adam Williamson <awilliam@redhat.com> writes:

AW> ...which you usually use for quoting, unsupported, as a reliable
AW> reference on anything.

So you're saying that the references in that article were inadequate?
The referenced article seems to have sufficient data to uphold the
conclusion, but of course I'm no electrical engineer.

- J<

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