Ramakrishnan's website

Common folklore (confirmed by some Norwegian friends) is that heat is not a friend of laptop batteries. The life of a laptop battery tend to reduce in Indian weather. One of the Dell Laptops I bought in early 2008 can now work barely 30 minutes with a fully charged battery.

Linux kernel provides a wealth of information (through ACPI) about the Battery like the make, type, serial number etc. Look under
/sys/class/power_supply/BAT0/. This is what I have:

~$ cat /sys/class/power_supply/BAT0/status
Unknown
~$ cat /sys/class/power_supply/BAT0/technology
Li-ion
~$ cat /sys/class/power_supply/BAT0/type
Battery
~$ cat /sys/class/power_supply/BAT0/serial_number
32511
~$ cat /sys/class/power_supply/BAT0/manufacturer
SANYO
~$ cat /sys/class/power_supply/BAT0/model_name
42T4511
~$ cat /sys/class/power_supply/BAT0/energy_full_design
84240000
~$ cat /sys/class/power_supply/BAT0/energy_full
64530000
~$ cat /sys/class/power_supply/BAT0/energy_now
63160000

It looks like, my battery (this is a work laptop, Lenovo Thinkpad T61 running Debian x86-64 unstable) is functioning at a lesser capacity than it is designed. It will be nice to corelate these readings with the actual performance of the battery. I tend to run this machine mostly with AC, but I will try profiling it for battery performance and see how much time these numbers translate to.