[ltp] T42p + Battery Rundown and results

[David A. Desrosiers]

> Li-ION cell refresh is a lot more difficult, and AFAIK the best you 
> can do without special hardware and fire hazard safety is to let it 
> charge to full, then discharge it *very slowly* to zero (e.g. leave 
> the thinkpad sleeping until it depletes the battery), then charge 
> again to full (to also reset the gague while at it).  Do it at 
> 20C-25C.

Further examination of the consumption with PowerTop revealed some 
interesting data. On a fully-exercised-and-fully-charged 9-cell 
battery, I am seeing the following.

On the lowest brightness setting, running at 600Mhz, my T42p is eating 
17.4W of power. The battery claims to have 1.4 hours remaining on 100% 
charge.

All of the possible power and performance tweaks have been applied, 
and powertop no longer gives me any suggestions for improvements. I've 
implemented about 20 of them total, which I've posted in my blog back 
in October of last year:

http://blog.gnu-designs.com/squeezing-the-watts

17.4W seems extrordinarily high for a laptop that is mostly idle, as I 
compose this email using pine in a shell. Nothing else is running that 
would eat power..

What else can I do to cut this power consumption in half? Anything?

powertop's output looks like this:

   Cn                Avg residency       P-states (frequencies)
   C0 (cpu running)        ( 3.5%)         2.10 Ghz     0.0%
   C1                0.0ms ( 0.0%)         1.80 Ghz     0.0%
   C2                6.3ms (84.3%)         1.60 Ghz     0.0%
   C3                7.4ms (10.9%)          600 Mhz   100.0%
   C4                9.8ms ( 1.2%)

   Wakeups-from-idle per second : 150.1    interval: 15.0s

   Power usage (ACPI estimate): 17.9W (1.2 hours) (long term:
   18.3W,/1.2h)