----- Original Message -----
From: "Henrique de Moraes Holschuh" <[email protected]>
To: "Richard B. Johnson" <[email protected]>
Cc: "Bill Davidsen" <[email protected]>; "Jean Delvare" <[email protected]>;
<[email protected]>; "Richard Hughes" <[email protected]>; "David
Woodhouse" <[email protected]>; "Dan Williams" <[email protected]>;
<[email protected]>; <[email protected]>; <[email protected]>;
<[email protected]>; <[email protected]>; <[email protected]>;
"linux-thinkpad mailing list" <[email protected]>; "Pavel
Machek" <[email protected]>
Sent: Friday, November 03, 2006 8:23 AM
Subject: Re: [PATCH v2] Re: Battery class driver.
On Thu, 02 Nov 2006, Richard B. Johnson wrote:
No known laptop bothers to do this. That's why the batteries fail at the
most inoportune times and why it will decide to shut down when it feels
like it, based totally upon some detected voltage drop when a disk-drive
started.
Weird, I though the whole point behind a SBS hardware stack requiring
something fairly intelligent in the battery pack and allowing for (runtime
switchable!) Ah or Wh modes of operation was to allow vendors to do
exactly
that: measure (V,A) permanently while the cells are above the safety
cut-off
fuse level, and accumulate it...
Well, IBM embedded a microcontroller of some sort on every SBS ThinkPad
battery pack, and the ThinkPad reports battery data in Wh, so I expected
it
to actually do the hard work to know how much energy is still left in the
pack... especially given how much $$$ they want for the packs :-) I have
no
idea of what software is really running inside the battery pack, of
course,
so maybe the SBS battery EC just sits there doing something else instead
of
taking real-time measurements of the battery charge (that wouldn't
surprise
me too much...).
I'm not sure anybody actually embeds a micro. There is some chip, originally
make by National, that
was supposed to monitor the battery state. I know that I have used five
laptops so far and have
never been able to obtain any intellegent operation. They just shut down
when they feel like it.
They do go to "suspend" mode to save power as well, always at the most
inopertune moment.
Maybe the "ThinkPad" actually has some intellegence within. The cost of the
batteries only reflects
the cost of defending lawsuits <grin> and not the cost of its components.
Batteries made in
China seem to become "excited" at inopertune times.
--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh
Cheers,
Dick Johnson
Penguin : Linux version 2.6.16.24 (somewhere). IT removed email "privileges"
for engineers!
New Book: http://www.AbominableFirebug.com
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