T42 Battery Life

[itsramesh]

Hi all,

I have a T42 (6 months old) and was wondering what kind of battery life is reasonable to expect. I thought centrino shd give 4 hours atleast for a 6-cell battery... but mine seems to be performing poorly.

power profile: High battery Performance (CPU runs at 200 MHz)
When watching a movie: 2hr 15min
Just plain web browsing: about 3hrs
Cycle Count: 52
Full-charge capacity: 40.39 Wh (supposed to be 47.5 i think)

I used to have the power profile at High-System performance (CPU at 1.7GHz i guess) and remember i could watch only 1hr 30min of a movie.
I used to have my laptop plugged in all the time so never really looked at battery life until now.
Should i get my battery replaced? Any advice appreciated.

[K. Eng]

You should be getting 3.5-4 hours on a new 6-cell battery.

Battery degredation is normal, and I would say 40.39 Watt*Hrs is about right for 52 cycles on the battery. I've got about 120 cycles on mine and I'm down to 28 Watt*Hrs

You can download a program called Mobile Meter at:
http://www.geocities.co.jp/SiliconValley-Oakland/8259/

This handy program shows you the CPU frequency, CPU temp, Charge or Discharge rate on the battery, and HDD temp. Run the program and see what the Discharge rate is on your battery while doing different tasks. Get a sense of the average discharge rate in Watts, and you can find your typical battery life.

For example, a battery with 26 Watt*Hr capacity will give 2 hours of operation when discharging at 13 Watts (26 Watt*Hr/13 Watts = 2 Hr).

Make sure your graphics chip has PowerPlay enabled in the drivers as well.

[itsramesh]

I downloaded the mobilemeter and the numbers match up as u said.

But more importantly ... why is the battery life dependant on the power profile? isn't peintum-M supposed to adjust speed by itself depending on whether u do a CPU-intensive task or not?

As i said .... high-system performance makes the cpu run at 1.7G and high-battery perf profile makes it run at 200MHz (shows up as 600 in mobilemeter, i dunno why).

Aside from that, isn't it time to get a new battery? (more so in your case since its down to 28?)

thanks.

[zver17]

so is it true that the cpu can go as low as 200mhz but the mobile meter reports it as 600mhz?

[kev009]

Without implicit underclocking 600MHz is the slowest you'll see out of a Dothan. Mobile Meter is reporting the correct speed and you are mistaken on the slow speed setting or you are running a third party app and mobile meter isn't picking it up correctly?

[Kenn]

so is it true that the cpu can go as low as 200mhz but the mobile meter reports it as 600mhz?

I've seen the 200Mhz before I reformatted and reinstalled. I know for a fact that Battery Maximiser's "Very Slow" setting, which was reported in System Properties as 200, was significantly slower than "Slow", which was reported at 600Mhz.

Now "Very slow" and "Slow" are the same thing, both report as 600Mhz. I could accept that it was reporting wrong and the CPU was at 600MHz the entire time, but there was DEFINITELY something that was different about the settings which made the entire system run noticeably 2-3x slower...in Very Slow, resizing a window was as choppy as it is on a Mac, and I couldn't get a smooth animation on anything...oh well.