It's better to disconnect the battery, but the other day when I had to take off my Polo steering wheel to adjust the spinwheel, my mate quite happily went to town on the wheel with a screwdriver with the battery connected, I said "feck off am I doing that, you can do it then if the battery isn't disconnected" but needless to say he really gave it some bangs with the battery to connected and nothing went wrong. But to be on the safe side you still should.