I would like to point out that lithium Ion batteries don't perform the same as lithium polymer... Nokias batteries are lithium polymer which means they discharge slowly and hold there charge but it also makes them expensive. Lithium ion are not as good at holding a charge on an always on device and discharge rather quickly, better suited for products designed to pull a large amount of energy such as a laptop. So a 1500Miliamp lithium Ion batter will not last anywhere near as long as a lithium polymer. This is why you should only use the nokia charger because lithium polymer batteries are prone to exploding when charged incorrectly.