So my younger brother got his Fascinate last night, I popped the cover off to reveal what I think was an H1 battery. I own the Epic, which has a G9. I believe the classic I9000 has a G7. So... what is the difference here? To my knowledge (I don't have his phone in front of me), the batteries are rated at the same voltage and mAh. They look identical, and I would imagine are interchangeable, but why the differences?