John Summerfield wrote:
>
> I don't understand LI batteries very well (and judging from reports I
> read, lots of others don't either), but given that there may be problems
> with their life, since the laptops are relatively low power, they're
> pretty kind to UPSes too, and the UPS can also power communications kit
> and maybe protect the setup from shocking phone lines.
>
>
> The State of a li-battery can be observed:
> 06:12 [summer@finch ~]$ head -99 /proc/acpi/battery/BAT0/{state,info}
> ==> /proc/acpi/battery/BAT0/state <==
> present: yes
> capacity state: ok
> charging state: charged
> present rate: 0 mW
> remaining capacity: 56790 mWh
> present voltage: 16673 mV
>
> ==> /proc/acpi/battery/BAT0/info <==
> present: yes
> design capacity: 57600 mWh
> last full capacity: 56790 mWh
> battery technology: rechargeable
> design voltage: 14400 mV
> design capacity warning: 2839 mWh
> design capacity low: 200 mWh
> capacity granularity 1: 1 mWh
> capacity granularity 2: 1 mWh
> model number: IBM-02K7054
> serial number: 575
> battery type: LION
> OEM info: SANYO
> 07:13 [summer@finch ~]$
>
This information is normally provided by a "smart chip" is the
battery itself that keeps tract of the battery state, and
recalibrate itself when you do a full charge/discharge/charge cycle.
The more common setup uses power from the battery to keep the
settings, and can cause you problems if you let the battery go
completely dead. The same chip controls charge rate, reports charge
stats, and may also turn off battery output when it gets too low.
(Some just tell the laptop they are dead, and count on the laptop to
stop drawing power.)
The chip can be a problem when you rebuild the battery - both
because you will probably remove power from it during the rebuild,
and because most will not recalibrate to a longer discharge time
after you rebuild the pack. There is a Linux package to talk to the
chip, and reprogram it, but you need to have the battery out of hte
laptop, and make a special serial cable to connect to the battery.
(It is not an RS-232 connection.)
Mikkel
--
Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!
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