I recently started using Mac OS Sierra and was monitoring battery life on my Macbook to determine whether it was more or less energy friendly. I noticed Spotlight is writing to disk a lot because it needs to index the files on your Mac.
I therefore decided to disable SpotLight indexing on my Mac. This guide describes how to disable the indexing for Mac OS Sierra. (But it will probably also work on El Capitan)
The steps are as follows:
Open the Terminal app. You can find it by opening Finder, Applications, Utilities.
Type the following command and press “enter”:
sudo mdutil -a -i off
If you want to re-enable SpotLight indexing later, you can simply open the Terminal app again and run:
sudo mdutil -a -i on
This will re-enable indexing.