While I can't directly answer your question, IIRC the FE2, which is similar in its AE function, only does a couple of minutes.
But mainly => you shouldn't even want to make such exposures in auto mode!!!
1) There is the film reciprocity error, which means that any auto exposure will be innacurate (assuming any meter reading will be accurate in that type of lighting anyway - tables of "rules" for different situations generally works better).
While you *could* compensate the exposure in AE, you wouldn't even know by how much to compensate for reciprocity failure....
2) 30 mins+ (if it even could) in AE will *really* run your battery down. "B" is definitely friendlier on the wallet...
Such time exposures are really the realm of tables and experience, not AE...
Good luck!