New iPod battery

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Alright, my Nanos battery life has become unbearable anymore so I dissembled a older 512 non working shuffle that I found and took the battery out so I can fit in the nano. The shuffles battery is soo small but its better but better to try than to waste, no? so Im thinking of putting this shuffle battery in the nano. the thing is the nano like in this picture http://www.ifixit.com/Guide/97/images_large/14.jpg, has 3 wires where as the shuffle only has 2 which are the black and red. i'm wondering if the white wire on the nano is for the battery status or the ground. does anyone know? if possible I want to connect both of the batteries together, will it even work like that? i'm going to soldier them together and see what happens. what do you guys think