ASUS U36JC from 4 to 7 hours of battery life with linux acpi_call

One of the linux hybrid graphics team members has reported that the ASUS U36JC laptop will go from 4 hours to 7 hours of battery life using acpi_call to switch on/off the nvidia card:

system-version
U36JC
1.0

00:02.0 VGA compatible controller [0300]: Intel Corporation Core Processor Integrated Graphics Controller [8086:0046] h(rev 18) (prog-if 00 [VGA controller])
01:00.0 VGA compatible controller [0300]: nVidia Corporation GT218 [GeForce 310M] [10de:0a70] (rev ff) (prog-if ff