I recently noticed that my Android phone was draining battery a lot faster than usual. So I checked out the battery page and discovered that Google Search was my top source of battery drain, more than Screen! That’s insane. None of my settings had changed so I didn’t understand why this was suddenly happening. Rebooting didn’t fix the problem.
Google Search was definitely the cause. From its app page, I saw that that Google Search was using up to 500 MB of storage, and was constantly restarting every minute or so and rebuilding that massive index. No wonder it was taking so much battery!
Searching online showed that other Android users has/had the problem, and that it wasn’t limited to my OnePlus One. So here’s my fix, after a painful day of research and experimentation: