Since kernel 2.6.24 in 2008, the /proc/acpi/battery interface is deprecated.
There is for years no updated kernel which wouldn't provide the /sys/class/power_supply/BAT0 in a laptop
This patch removes the useless old path, and uses the sysfs to provide 3 informations :
- current flow in mA (charge or discharge)
- charge percent against last completed full charge
- charge percent against battery by design charge