Power Management

[brad longo]

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.
>
>   
Thanks this is the information I was looking for.

--Brad