Volvo Sport Key

When the battery dies on a Volvo sport key the official solution is to replace the whole key, but it is possible to replace the battery by carefully opening the case and desoldering the original battery and replacing it with one like this, CR2032 Lithium Battery CMOS backup memory with solder tabs. Be careful when soldering, I damaged my board and had to repair the pads during the process, but it still works. I plan on making a new version sometime in the future with that uses a battery holder to make battery replacement even easier. 

Battery holder version is now available, there's a little more work involved with this one, such as trimming the body of the holder to fit the case, cutting one of  the positive pins off, and soldering a wire between the negative pin and the board, but it'll make future battery changes much more user friendly without having to worry about damaging the board. I used the case to locate the holder and hot glued it in place, thin double-sided tape would probably also work.