It appears that this lens just sucks the life out of batteries. I shouldn't be surprised really with those long slow AF times. I guess it's an 'all or nothing' lens on all fronts!
I've read about this before but it only affects 40D's !
On a 5D or 30D then battery life doesn't suffer much more than any other lens and similar to an IS lens.
There are a few tricks....read this from POTN as a work around http://photography-on-the.net/forum/showthread.php?t=483247....WimG's posts specifically.
Bob
LOL. Narrow escape then Wack!