Maybe it depends on where the batiks come from. I've used some like it was any other fabric and had no problems. But recently I was given a gorgeous set of coordinating blues in 6" squares (two of each), origin unknown. I decided to soak them, and a few bled and one twinset in particular oozed color, even after a couple of soakings. I was glad I decided to check them for color fastness.
I just had a hunch about those, but like I said, I've used others without washing with no problems. Guess I'm not much help!