[ltp] x61s battery life time

[Theodore Tso]

On Thu, Feb 07, 2008 at 03:37:56PM +0100, svoboda@fi.muni.cz wrote:
>
> regardless using Vista or Linux i have 2.5 hours of working time. I think 
> it depends on the battery pack you use. I have 4 cell Li-Ion battery with 
> the capacity of 2.0 AH. Which one do you have?

There are 3 primary batteries for the X60/X61 series:

* Thinkpad X6x 4 cell slim line battery    28.8 Watt hours (3 hours @ 9.3 W/hr)
* Thinkpad X6x 4 cell cylindrical battery  37.4 Watt hours (4 hours @ 9.3 W/hr)
* Thinkpad X6x 8 cell battery              74.8 Watt hours (8 hours @ 9.3 W/hr)

How many hours you will have depends on what your laptop is doing and
how you configure it.  9.3 W/hours is what I get when I put my laptop
in "Airplane mode".  (That is, wireless disabled, USB modules
unloaded, screen brightness at 40% using xbacklight, bluetooth module
disabled, laptop_mode enabled, all of my mail messages loaded into
main memory so there is minimal or no disk activity, etc.)  So the 9.3
W/hr consumption is not the lowest possible number, but it's the
lowest possible *realistic* number that I've been able to find, which
involves me reading e-mail and mostly deleting mail messages using the
mutt mail-reader.  Your Mileage May Vary; in particular, if you are
using Evolution to read your mail, it's almost certain it will be
burning more juice.  :-)

People who say that they get 2.5 or 2.2 hours battery life are
probably using the the 4-cell slim-line battery (assuming their
battery is new), and running 11-13 Watts/hour, which is quite
believable.  If I'm running at full screen brightness and doing a CPU
and Disk intensive workload, I can drive the usage up to close to 30
Watts/hour.   So it All Depends.

There is no question that Windows is better at making it easy to
configure your laptop on the continuum between high-performance and
long battery life, and it *may* be the case that Windows can drop to a
lower baseline idle usage level.  (I've seen some people claim 7-8
W/hr on Windows XP; but I can get to around 8 watts/hr if I turn the
screen all the way down, but it's not really usable at that level.  I
haven't seen a fair, heads-to-heads comparison using exactly the same
hardware, and adjusting both laptops to a similar idle configuration.)

In any case, trying to crowbar Linux's power consuption down the
lowest possible level when it is idle is fun, but probably the biggest
development gap is making it easier, and preferably auotmatic, for
Linux to change its power usage profiles when on or off the AC mains
power, and ways to automatically and easily turn off such as the USB
port when they are not needed.

						- Ted