ThinkPad T42 & non-OEM 9-cell batteries

[rzl]

Hello people.
I just got 2nd hand T42 and a friend of mine sold me his almost-new 9cell battery.

I am now using this TP with Debian GNU/Linux 5.0.6 «Lenny», and KPowerSave says there are 95% of the battery life remaining, which are about 4:16 hours (as kpowersave and acpi say).

But... shouldn't this battery last more than a little bit more than 4 hours ?
Is there a way to re-calibrate the battery?

I remember there was a method in my old asus laptop to boot the laptop from the bios and let it run until the battery had ran out of power, to recalibrate the acpi subsystem.

Is it possible to do something similar with the ThinkPad T42 ?

Thanks in advance,
Rzl

ps: this laptop ROCKS!!

[frankiepankie]

I think 4 hours is quite good. T42 isn't as power saving as the modern laptops with Intel i5.

[Temetka]

I'd be happy with 4 hours of battery life.

There is some lenovo software (power manager 3) which can perform a battery guage reset. However it must be run in Windows. I do not know if the software will operate inside a virtual machine.

[T400plus]

check the power status of the battery.It might be only half alivee and thats why it is giving only(!) 4 hrs.A new 9 cell would give approx 8-9 hrs. I have used a non IBM 9 CELL battery and till i burnt the mother board it used to give me 5-6 hrs at maximum power settings.
Of course,miine was only a first generation T41 ..
check the battery status using lenevos power manager under windows.

[dr_st]

A new 9 cell would give approx 8-9 hrs.

Never. Not on this machine.

[craigmontHunter]

Never. Not on this machine.

I used to get 3 hours on a t41 that could only hold ~25/30% of it's original charge on a 6-cell. Of course, I turned everything down, and on my t61, with the same settings, I get 5.5 or 6 hours of wireless battery life.

[dr_st]

I used to get 3 hours on a t41 that could only hold ~25/30% of it's original charge on a 6-cell. Of course, I turned everything down

Including the screen and the computer? Then it is more believable.

The original 6-cells for a T41 were 47.52Wh. Let's assume that maybe you had a battery from a T43 (51.84Wh). Let's assume that it had 30% of its original charge left. You say it lasted you for 3 hours, which would mean that the computer was using on average 5.2W of power. Even X series can't typically achieve that even with CPU on maximum power saving and the screen on minimum brightness. I'm sorry, I don't believe your numbers.

[craigmontHunter]

I know that I could get it down to about 8.5 Wh, and I guess my problem is that I forgot to mention the screen would blank very quickly, 1min or so, and when I am using a computer constantly, I will get distracted and sit, ready to type, hands on the keyboard for 5 minutes, and stare out the window. So yes, my numbers can be taken with a large salt shaker, since you need more than a grain. I do know that it would get me through 2 classes and a bit more in high school - almost 2.75 hours, and I also know that my battery was never above red, whatever that means. When I turned off wireless, and the screen all the way down, and idled with a word document so that the hard drive did not have to spin, I got 3 hours, since it lasted from ottawa to North Bay on a car trip once, and I used it the whole time.

I may just be extremely lucky, or my battery was mis-reading (also entirely possible)

[dr_st]

I may just be extremely lucky, or my battery was mis-reading (also entirely possible)

Indeed possible. I have an old T42 battery that shows ~15Wh, which theoretically should last for ~30-40 minutes in the normal usage patterns, but when you actually start using the battery, and it gets to 0%, it then sits there for about 20 more minutes before the PC finally turns off. So an inaccurate meter in an old battery is something totally believable.

[craigmontHunter]

I wish that I could remember better, but it has been 6 months since my t41 died, and a year since it stopped running on batteries. I do know that my dell would hit 0%, then run for another hour before it would die.