You need a rather strong iron (some 40W minimum) for that. Unsoldering should be really simple, by pushing a carton or thin steel/alu sheet under the foot of battery cell while heating up the foot until solder melts. Soldering new cell needs at least basic experience with soldering. Ideally you clean the pads (use desoldering braid), (use flux and) wet them with a small amount of new lead solder (~60/40 multicore, max 1mm diameter), then likewise wet the feet of coin, again treat both the pads and the feet with no-clean SMT flux, then make sure you place the coin right way around on the pads and heat each foot until the tin reflows and foot connects nicely to the board. You should use sufficiently hot iron for that or you will overheat the battery cell (yes, since lower temperature causes longer processing time which heats up battery more than a short really hot spike). When you're an experienced solder iron artist, you may get away without flux, and you'll know how to solder that coin so it doesn't overheat. for the rest of you: everybody can do this when you use the right tools and solder and flux. But when you got one of them in the crappy variant or think of trying without flux for example - better don't!

The battery is not needed for anything relevant except RTC. Proof: N900 with broken bupbat work "flawlessly", except for losing date&time on battery swap. [edit] Note that the RTC also stores an alarm that boots up the device from power down when set. Of course this will also get lost when bupbat is defect and you swap main battery!


I hope I managed to process all orders and you all received your bupbat. If somebody didn't, please holler! This is not a planned scam

cheers
jOERG