Funny battery values (nx6325)

[Joerg Wunsch]

As Joerg Wunsch wrote:

> > Joerg, so how long does it really run on battery?

> I'll try that as soon as possible (the machine is the
> production-level machine of my wife...), and I'll use the
> single-user method so the battery can actually drain down until it's
> really empty.

It lasted 1.5 h at a reported current of about 2.3 A, so the actual
capacity is around 3.5 Ah, which is certainly a reasonable value for a
3-year old LiIon.  I couldn't wait until it shut off itself, so I
eventually stopped the procedure when the reported voltage reached 9.0
V (i.e., 3.0 V per cell).

Battery state reporting went a little funny.  As expected, it
initially dropped quickly until it reported a remaining runtime of
0:00 (as that time was based on the nonsensical 279 mAh level).  At
that point, the report was stuck at the same values for maybe 30 or 40
minutes, until ACPI eventually reported a "battery is seriously low"
event.  Then, it started to report actual data (battery voltage,
current draw) again.

Alas, the reported values now are still way off:

remi# acpiconf -i0
Design capacity:        791 mAh
Last full capacity:     791 mAh
Technology:             secondary (rechargeable)
Design voltage:         10800 mV
Capacity (warn):        40 mAh
Capacity (low):         8 mAh
Low/warn granularity:   100 mAh
Warn/full granularity:  100 mAh
Model number:           Primary
Serial number:          00784 2006/10/04
Type:                   LIon
OEM info:               Hewlett-Packard
State:                  discharging
Remaining capacity:     99%
Remaining time:         0:39
Present rate:           1190 mA
Voltage:                12017 mV

Given that I now now it's got more than 3 Ah, having the battery
report 791 mAh is certainly not understandable.  But I'm now sure it's
nothing in our ACPI code that is bogus but rather the battery itself
(and the ACPI BIOS not implementing a real "design capacity" value).

Thanks to anybody contributing to the discussion!

-- 
cheers, J"org               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/                        NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)