I would just avoid buying third party batteries, it might discharge fast, swell or explode, make your mobile unstable (it did it with my 5800, had to buy a fake for an emergency), and i wouldn't be surprised if it's able to fry your mobile if it doesn't give stable voltages, or it might just be a low mah in a very shiny packaging, just buy the original, it's not like they are expensive, plus they live much longer without loosing capacity.