That's not really ideal though... for example, Windows Indexing is responsible for indexing email in Outlook. If you've been mobile for the last two days, that's potentially a lot of email you can't search.

Reminds me of a somewhat unrelated scenario in Android world. Auto backup of photos in Google+ Photos has a setting where you can have backup only happen when connected to power (and/or on Wi-Fi). Perhaps Microsoft could add something like this in their settings as well?

Yes, I understand this could be seen as feature creep but I think if the savings in battery life are as much as the grandfather says then it is worth the extra complication of a setting. What do you think?

Laptops can't really stay mobile for 2 days. At some point, it needs to power up, and your indexer can do the deed then. Too bad Windows doesn't have something like PowerNap that allows the system to run services while the clamshell is closed.

How often do users search in Outlook? I'd say maybe 5-10 times a day, and if it's already indexed, I won't notice.