[ale] what the heck battery reading

Fri Feb 18 16:38:14 EST 2011

Jim,

Thanks for the note.  Based on what you said, I've been searching for 
ubuntu battery calibrate in Google.  Nothing conclusive yet, but I'll 
share whatever I find.  I'm going to try a complete discharge and 
recharge cycle starting from a full battery, while Linux is running.  
The problem is, I don't know if the machine will shut off at the proper 
time.

Below are some links and info I found.

Sincerely,

Ron

----------------------

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

quote on -->

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.

Although lithium-ion is memory-free in terms of performance 
deterioration, batteries with fuel gauges exhibit what engineers refer 
to as "digital memory". Here is the reason: Short discharges with 
subsequent recharges do not provide the periodic calibration needed to 
synchronize the fuel gauge with the battery's state-of-charge. A 
deliberate full discharge and recharge every 30 charges corrects this 
problem. Letting the battery run down to the cut-off point in the 
equipment will do this. If ignored, the fuel gauge will become 
increasingly less accurate. (Read more in 'Choosing the right battery 
for portable computing', Part Two.)

<-- quote off

quote on -->

The worst condition is keeping a fully charged battery at elevated 
temperatures, which is the case with running laptop batteries. If used 
on main power, the battery inside a laptop will only last for 12-18 
months. I must hasten to explain that the pack does not die suddenly but 
begins with reduced run-times.

<-- quote off

quote on -->

There are no remedies to restore lithium-ion once worn out

<-- quote off

quote on -->

*Simple Guidelines*

    * Avoid frequent full discharges because this puts additional strain
      on the battery. Several partial discharges with frequent recharges
      are better for lithium-ion than one deep one. Recharging a
      partially charged lithium-ion does not cause harm because there is
      no memory. (In this respect, lithium-ion differs from nickel-based
      batteries.) Short battery life in a laptop is mainly cause by heat
      rather than charge / discharge patterns.
    * Batteries with fuel gauge (laptops) should be calibrated by
      applying a deliberate full discharge once every 30 charges.
      Running the pack down in the equipment does this. If ignored, the
      fuel gauge will become increasingly less accurate and in some
      cases cut off the device prematurely.
    * Keep the lithium-ion battery cool. Avoid a hot car. For prolonged
      storage, keep the battery at a 40% charge level.
    * Consider removing the battery from a laptop when running on fixed
      power. (Some laptop manufacturers are concerned about dust and
      moisture accumulating inside the battery casing.)
    * Avoid purchasing spare lithium-ion batteries for later use.
      Observe manufacturing dates. Do not buy old stock, even if sold at
      clearance prices.
    * If you have a spare lithium-ion battery, use one to the fullest
      and keep the other cool by placing it in the refrigerator. Do not
      freeze the battery. For best results, store the battery at 40%
      state-of-charge.

<-- quote off

On 02/18/2011 02:44 PM, Jim Kinney wrote:
> Don't recall details but I think there's a way to calibrate the
> battery monitoring app. It involves running down the battery a bit and
> recharging for a while and making calculations from that. Not finding
> how on a quick google search.
>
> On Fri, Feb 18, 2011 at 11:41 AM, Ron Frazier
> <atllinuxenthinfo at c3energy.com>  wrote:
>    
>> I'm running Ubuntu 10.04.  I have the Gnome power management icon set to
>> display all the time on my laptop.  If I left click the icon, I get two
>> lines on a menu.  The bottom, preferences, lets me set the power
>> management preferences.  The top line says Laptop battery is charged (at
>> the moment).  However, you can click on that line.  When you do, you get
>> a detailed statistics screen.  You can click on the ac adapter, the
>> battery, or the processor.  If I click on the laptop battery section,
>> then the details tab, I get lots of info about the battery.  It says the
>> capacity of the battery is 57.7 %, but the current percentage is 100%.
>> I've noticed sometimes that, when the battery is discharged, and I let
>> it charge back up while Linux is running, it stops charging at this 57 %
>> level.  However, if I shut down Linux and let the computer charge the
>> battery while the machine is off.  It fully charges.  I think Linux is
>> confused.
>>
>> So, my questions are:
>>
>> 1) How does Linux get it's numbers, from the battery itself, or from
>> calculations within the program?
>>
>> 2) How do I make Linux forget what it thinks it knows and recalculate so
>> my battery can fully charge?  Windows seems to sense the battery's
>> charge level fine.
>>
>> 3) Gnome power manager defaults to shutting down the pc at 1% of battery
>> remaining.  I can only tell it what to do at a critical battery level,
>> not what the level is.  For this machine, this is only 1 minute, barely
>> enough time to shut down.  For another machine (with a UPS), that is
>> only a few seconds, and would probably crash the machine.  I need to
>> know how to set the levels of charge where the warning appears, and
>> where the shutdown or hibernate happens.  I'd prefer not to have to load
>> another power management program if possible.
>>
>> Any help would be greatly appreciated.
>>
>> Sincerely,
>>
>> Ron
>>
>>      

-- 

(PS - If you email me and don't get a quick response, you might want to
call on the phone.  I get about 300 emails per day from alternate energy
mailing lists and such.  I don't always see new messages very quickly.)

Ron Frazier

770-205-9422 (O)   Leave a message.
linuxdude AT c3energy.com

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mail.ale.org/pipermail/ale/attachments/20110218/850a4c6f/attachment-0001.html 