On Fedora 22 cleanly installed, this is what I see in Settings > Power:
Automatic suspend: Off
When battery power is critical: Hibernate
There are no choices, those are fixed settings that I can't change.
The actual behavior I see when the battery gets critical though, is
suspend, not hibernate. First there is a message the machine is about
to be hibernated, but then:
Sep 27 02:45:38 f22m.localdomain systemd-sleep: Suspending system...
I get the same results with Fedora 23, with one exception in Settings
Power "When battery power is critical: Hibernate" is not
all, just that automatic suspend is off.
Anyway, the system suspends, but there is no battery power so the
suspend to RAM is lost, and it's entirely possible if not likely that
there will be data loss or fs corruption as a result.
Also cc'ing test@ because I'm not seeing a test case for this. It
seems to me that out of the box we shouldn't be risking people's data
like this, but it's not like poweroff -f is a whole lot better (except
for the fs portion).