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Re: power management problems

From: Bob Proulx <bob(at)proulx.com>
Date: Wed Sep 19 2007 - 12:59:13 EDT

I realize this is getting old but... I am just now getting back to it.

Ritesh Raj Sarraf wrote:
> rrs@learner:~$ cat /proc/acpi/battery/BAT0/state
> present: yes
> capacity state: ok
> charging state: charging
> present rate: 619 mA

What is your state when running on battery? The above shows it charging at 619mA. But the discharge rate would be interesting in projecting how much battery life *should* be available. For example my T42 (with my bad battery) shows:

  charging state:          discharging
  present rate:            16033 mW
  ...
  design capacity:         47520 mWh
  last full capacity:      23300 mWh

This battery has only half of the design charge available. (It is basically shot. I use it whenever I am going to have the laptop plugged in for long periods of time.) 23300 mWh / 16033 mW = ~1.45 h For me this is a fairly accurate prediction of battery life.

> remaining capacity: 286 mAh
> present voltage: 12590 mV
> ...
> design capacity: 4800 mAh
> last full capacity: 1003 mAh

With a last full capacity of 1003 mAh and a similar discharge rate as my T42 of 1335 mA would yield around 0.75 hours or 45 minutes of projected battery life. Your report of 10 minutes would mean 1003 mAh / 0.66 h = 6020 mA or just around 6 Amps! Wow. My laptop burns 1.3 Amps. That is a huge difference and one that I find hard to believe that a laptop could drain at the rate of 6 A.

This information should also be available under other operating systems. I think looking at the discharge rate in the different systems would be a good indication of how well things are working between the two of them.

For my T42 the MS discharge rate is lower at 1.17 A than the Linux discharge rate at 1.33 A and I have not been able to completely reduce that gap. Display brightness is a large power lever. I can also save some additional power by disabling unused components when they are not used such as the dvdrom, usb, and wifi but as far as I can tell the MS system does not disable those components and so I have not been able to reconcile the differences. Fortunately for me it is not a large difference. But I would like to close the gap just the same.

Do you need help?

> If possible, Please CC me when replying. I'm not subscribed to the list.

Sorry, I missed this request in my previous response.

Bob

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Received on Wed Sep 19 12:59:29 2007

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