@ Will-I-Am
The 'key' works because on my connector on the battery pack, there are only three holes, so you can't connect it wrong. Well if you know which is + and -, then go for it. I can't see the harm. And yes, your battery will just run down like mine, but I suppose when yours is flat you can put it in the phone to recharge whereas I gotta buy a new one.
I am also thinking of modifying my case: but I ahve less to lose because my case in bad condition. I was thinking of brushed aluminium for mine.