[ltp] Re: poll: how is your battery? (9-cell-battery lost about 25% capacity in 10 months)

[linux-thinkpad@linux-thinkpad.org]

On Thu, 14 Jul 2005, David A. Desrosiers wrote:

> 	After a lengthy call with "Harold" in IBM Atlanta yesterday, he 
> suggested I download the "PC Doctor for DOS" on the ibm.com website to help 
> diagnose/fix the problem with the battery issue.
>
> 	So I searched around the house to find 3 floppy diskettes (not an 
> easy task in these times, I haven't used a floppy in literally years!). I 
> copied the PC Doctor images to floppy, booted each one up, and ran the "Full 
> diagnostics" from the application on my personal laptop. "Harold" wanted me 
> to see if there was an error code or other error that would show up that 
> could help him diagnose it on his end, to see if the charging circuit was 
> bad, or the battery, or some other component of the system.
>
> 	But buried in the menus of PC Doctor for DOS was an item called 
> "Battery Rundown", which basically churns every device it can to completely 
> drain the battery. CPU, floppy, screen, coprocessor, and everything else.
>
> 	I ran both of my T23 batteries down to nothing, to the point where 
> the laptop yells with the loud klaxon warning "BEEBOOOBEEEBOOO" and then 
> shuts down.

David thanks for this, it may prove very useful.  I've just tried to
repeat yours and the enigmatic "Harold"'s (wasn't he on Neighbours? -
it's nice to see he's still in work) experiment.  PC Doctor is also
under standard diagnostics if you haven't deleted the XP recovery
partition on your thinkpad - just hit the IBM button at startup,
choose "Run Diagnostics", then "Utility" then "Battery Rundown".
As you say, it runs *everything* to hammer your battery; and I think
the key here is that there's no substantial OS to get in the way and
shut down your machine when it receives the critical battery warning -
it just keeps going until it's really rundown.  Lithium Ion batteries
need to do this once in a while (rarely! often isn't good) to calibrate
themselves, as long as the device controlling them doesn't genuinely
empty the cells, which I assume PC Doctor won't.

I've only just completed the exercise, so can't report what /proc/acpi
is going to tell me: it only reports "last full capacity" and it's
still charging back up.  But I can report that it went past the warning
(single toned beeps) and then critical warning (two tones, battery
light flashing), when Linux would have shut the thing down, at 52
minutes, and it didn't finally shutdown until 83 minutes.  This was
with a 6-cell (the smaller one) T40 battery, about 15 months old.
I don't expect these times represent real lifetimes, as the test really
does hammer everything, so I expect to get more than 83 minutes from
my battery in a real situation now, which is a real improvement.

My guess is therefore that the battery is saying it's nearly flat when
it's nothing like, and the OS is acting accordingly - a calibration
problem, which isn't solvable by running the battery down within
Linux/XP, as it doesn't know the battery's lying.  Only guesses,
as I don't know so much about battery technology.

I'm hoping that this may be a partial answer for me, and for some of
the rest of us with what seems to be decaying battery life after a
relatively short lifetime.  I guess I'll know when it's charged back
up.  But it's an easy enough exercise to try.

Honey