The battery of my netbook is getting senile and one small trick I use to save the battery life is to disable bluetooth at boot. The trick is very simple, just use a text editor (as root) to open the file /etc/rc.local and before the last line, add the following line:

 rfkill block bluetooth  

Here is how this file look in my Linux Mint system afterward:


From now, Bluetooth will be automatically turned off in the next boot. Similarly, if you want to disable Wifi at boot as well, you can just use this line:

 rfkill block wifi  

Note: If you have any problem turning on bluetooth and wifi after using this trick, just open the terminal and run the following command to check which device is being blocked:

 sudo rfkill list all  

After that, to re-enable, for example wifi, you just need to remove the line in /etc/rc.local and use this command:

 sudo rfkill unblock wifi