He is talking about a hardware hack to lower the brightness of the Kobo Glo which I posted a few months ago:
See here
To change the refresh rate in daymode,
see here, to change it in nightmode, edit the value of refreshScreenPages in nightmode.ini.
@akorx:
These screens draw a lot of power (~1.5W, much more than a LCD screen of this size)
during update, but use almost nothing in standby. So it makes sense that the battery lasts longer when you aren't using full refreshes, since these take roughly 2-3 times longer than normal screen updates. The hardware hack should be battery neutral, but I haven't measured it yet.