Always wondered this. I have a MBP 15" Late 2011, MBP 13" Late 2011, and also MBA 13" 2011. Can the 85W power adapter from the MBP 15" be used to also power the other 2 machines? I ask because, my MBP 15" is from work - and when I use it at home several days a week, I have tie-wrapped the 85W adapter onto some existing cables for cleanliness - making the removal of for daily outside use not possible. Meaning I would like to use the same MagSafe power adapter to charge/use all 3 MacBooks when I move from one to another - without whipping out a dedicated power adapter. No risk of damage due to TOO much power? No risk to battery overcharge due to higher power adapter.