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Douglas, there is no chance that the springs are to hold a battery. There is no room for a battery of any sort. The back cover as a metal disc of more or less white metal in the centre about 1cm in diameter, around that there is a thin plastic (insulating) ring and that is surrounded by a ring (an annulus) of yellow metal. One of the springs, which are tiny, touches the centre disc, the other touches the yellow ring.
SlackAlice, the whole item is no bigger than two AAA batteries.
Hans, the distance between the springs is about 1 mm. There is no receptacle for a battery to fit into. Also see first paragraph.