Mikkel L. Ellertson wrote:
John Summerfield wrote:
it's something I often say in jest, but true nonetheless. A laptop can
make a good low-end server, and as you say, it comes with a built-in UPS.
One problem you will probably run into is that the batteries in most
laptops will lost run time if you do not do a long discharge/charge
cycle every so often. I know two many people that are using a laptop
as a desktop because of space considerations, and have had the
battery degrade to less then 10 minutes of runtime, while the same
model laptop where they have used the battery (actually used it as a
laptop.) has 90 minutes or more of runtime. I am not sure if this is
because of the differences between the lead/acid gel-cells used in a
UPS compared to the lithium-ion batteries, or if it is the battery
charge monitor gets confused by the short charge/discharge cycles. I
do know that the lithium-ion battery charge can not be measured by
voltage level like the lead-acid batteries can. Bye the time the
voltage starts dropping, they are almost dead.
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 ~]$
--
Cheers
John
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