A hlaf hour of run time doesnt sound out of the ordinary with that size of a pack (wish it was a higher C rating but thats a different story).

Check your settings using the castle link software. The LVC will kick in and you should just have steering at that point. 6.0v is a little lower than I like (usually leave it at 2.3v so 6.6v total) as if you have one cell that is weaker it might dip under what I would be comfortable with.