Funny battery values (nx6325)
j at uriah.heep.sax.de
Wed Mar 17 16:18:37 UTC 2010
As Kevin Oberman wrote:
> FWIW, IBM/Lenovo recommend that, should the battery capacity stuff
> get messed up, you FULLY discharge the battery and then re-charge.
I'm doing that right now with my TP 600E battery, too. It was
completely dead (one out of the three cell pairs had 0.0 V), so I
replaced all cells by some other 18650 cells I've got around. While
the machine yelled "Battery critically low" after only about 5 minutes
of run-time, it already lasts for half an hour now. I hope I'll also
be able to re-train the Coulomb meter chip in the battery there.
> This is claimed to re-initialize the values stored in the battery
> and I found this worked on a battery in my old 600E. Mine did not
> have a weird "Design Capacity" value, though.
Same here, the "Design capacity" of that TP 600E battery makes sense,
unlike on the nx6325.
As Ian Smith wrote:
> > > Is this consistent or does it vary from boot to boot or if you
> > > disconnect and reconnect the battery?
> Or try another battery?
Only got that one. The machine is normally a semi-desktop one.
> > That's right, but it wouldn't be supposed to affect the "Design
> > capacity", would it? ;)
> It wouldn't be supposed to :)
> Tracing back through acpi_cmbat_get_total_battinfo in acpi_cmbat.c
> indicates that calculaing remaining time does uses last full
> capacity, but from there back through acpi_cmbat_get_bst and
> acpi_cmbat_get_bif it's all just retrieval, from acpi packages of
> _BST and _BIF
Thanks for the analysis!
> Most of it must be stored in the in-battery chip, but I don't know
> where specs may be, or even whether they all use same protocols.
I think this is all called the "Smart Battery specification", which is
essentially a layer on top of a standard I²C bus. I once looked at it
lightly in connection with a battery control IC as I did build my own
battery (out of used 18650 cells, again) for a ham radio transceiver.
But I haven't really looked into the Smart Battery specs so far, as my
transceiver didn't want to talk it anyway. ;-)
> Peter's factor of 10 sounds plausible.
Except for the design capacity value.
> You can dump your ASL (see Handbook for instructions) and search for
> something like:
Thanks for that hint, I'll do it as soon as the machine is back here.
cheers, J"org .-.-. --... ...-- -.. . DL8DTL
http://www.sax.de/~joerg/ NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)
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