Run Hazel when only connected to AC power

is there a way to only run hazel rule (s) when my macbook is connect to AC power and not the battery?

Thanks

No way to do that at the moment. Maybe you can record your user actions to an AppleScript/Automator and find a program that can detect switching from AC to battery to trigger it.

Also, keep in mind that the rule engine in version 3 is a lot more efficient and any battery drain should be minimal. Though if it is a big deal now you may want to look at your rules to see if anything you are doing is unnecessarily resource-intensive.