The battery conservation mode is enabled with:
$ echo '\_SB.PCI0.LPCB.EC0.VPC0.SBMC 3' | sudo tee /proc/acpi/call
It can be disable with:
$ echo '\_SB.PCI0.LPCB.EC0.VPC0.SBMC 5' | sudo tee /proc/acpi/call
On Debian/Ubuntu you should install the package acpi-call-dkms
(Credits: ArchLinux wiki - Lenovo IdeaPad 720s)
The just mentioned wiki page refers to the IdeaPad 720s, on my IdeaPad 320 I've double check on the BIOS DSDT table and it seems to be the same. Browsing the web, I've found a case where the proper code to enable it was 4 (instead of 3) but 5 was used to disable it in any case.
Edit Edit Edit
The battery conservation mode is now exposed via the kernel module ideapad-laptop
, so just load the module and then use:
# to read the current status
cat /sys/bus/platform/drivers/ideapad_acpi/VPC2004:00/conservation_mode
# to enable
echo 1 > /sys/bus/platform/drivers/ideapad_acpi/VPC2004:00/conservation_mode
# to disable
echo 0 > /sys/bus/platform/drivers/ideapad_acpi/VPC2004:00/conservation_mode