Comment 9 for bug 494772

Well, I got 3/4 through implementing it, then I found that an implementation already exists in update-notifier/src/update.c !
Function is called running_on_battery, but it is commented out (as well as the bit of code that uses it in auto_launch_now. (I wonder if that should really be done before doing update_check, to save battery power).

Anyway, the message is: "disabled because we need more cleverness here in order to cover the case where people always work on battery (and charge overnight)"

It's a good point. I had prematurely marked the update-manager part of this as invalid. In fact, that may be the best place to fit an alternative solution. Perhaps a little notification bar attached to the main window - as opposed to the modal dialogue box - reminding the user that updates consume lots of battery power. A change in the tone of the message makes sense to me, too, since the current one does not explain anything; it just says that the user is on battery, which he/she probably knows.

On the other hand, there's still the nagging thought that we should not perform heavy operations such as checking for updates _in the background_ when the user is on battery without first asking if it is okay. Maybe the Ayatana people have an opinion on this?