I had 11.10 X86 on my Asus laptop (sandybridge, Nvidia 520M). I had 8 hours' battery life with Bumblebee and Jupiter. Average battery discharge rate was around 10w. Later I changed, not upgraded, to 12.04.1 AMD64. I installed Jupiter. But there is no "restricted drivers" available so I guess Bumblebee will not work. So I removed nvidia drivers. Now I only get 4 hours' battery life. Average battery discharge rate is around 19w. The removal of nvidia driver did not make any difference.
What's the cause? Nvidia video card not disabled or 64b version of Ubuntu?