Comment 7 for bug 519484

The problem with never prompting on battery power is quite simple: someone may always use their notebook on battery, never on AC, charging it only when it is sleeping or turned off. In that case, they would never be prompted.

With the fix to bug 426708, the prompt is in the main window, rather than a separate alert, and says "It’s safer to connect the computer to AC power before updating." I think this removes the annoyance describes here. If so, this is a duplicate. If not, I think this will have to be Invalid.