You can also program the old style 3 button remotes even if your BMW has the newer diamond shaped remotes. These remotes have the removable back and replaceable CR2016 battery...so keeping the key charged up is as simple as keeping it supplied with a fresh battery.
FYI...as previously mentioned...regardless of old style or new style...the key has to operate on the same frequency as your vehicle and other key (315 MHz in USA & Canada...433 MHz in Europe and many other markets in the eastern hemisphere of the globe).
