Disable DRI when on battery

[Flyser]

As I use the DRI extension of X.org from time to time, I was wondering
if it is possible to disable it, when on battery. But think neither X
nor fglrx does support it, thats why I created a "mobile" runlevel, now
I was wondering I it is possible to let X.org check if the system is in
this runlevel and disable dri in this case. This requires X to restart,
but better than nothing ;)