SMC Firmware Updates for MacBook Pro, MacBook Pro Retina, and MacBook Air
Apple has released three System Management Controller (SMC) firmware updates for its MacBook lineup: MacBook Pro SMC Firmware Update 1.8 (703 KB; mid-2012 models), MacBook Pro Retina SMC Firmware Update 1.2 (712 KB; mid-2012 models), and MacBook Air SMC Update 1.9 (1.09 MB; mid-2012 and mid-2013 models). All three address battery-related issues, where your system could hang or the battery could stop functioning altogether if the battery level goes below 1 percent. The MacBook Air SMC Update also throws in a solution for the possible problem of the system not recognizing the battery when it
goes below 1 percent. As always with firmware updates, we recommend relying on Software Update or the App Store app to ensure you get the firmware update for your specific model, and be careful not to interrupt the update process. (Free)
I have downloaded this 13 times and it says it installs it and restarts and the update icon reappears when the restart is done
Are you letting Software Update or App Store do the downloading? And do you have a firmware password set for your Mac (no idea if that's related, but it feels like it could be)?