*Volvic Revives thread*
I did my own little test, with my M3 Real. I used the Zelda Phantom Hourglass Main Menu cinematic on loop, at full brightness.
Without GBA Expansion: 3:45 (225 min)
With GBA Expansion: 2:55 (175 min)
The maths says that battery life is shortened by 22%, or that power consumption has increased by 28% by simply having the GBA Expansion plugged in.
I'm convinced that my Battery is dying though, since I'm pretty sure it's been through at least 300 charge cycles in the last year. It's been left plugged in while running countless times, too.