” this would cover my needs with room to spare”
That is so very subjective.
If you really want to be able to be able to make sure you can keep the computer and
hard drives running for an hour or so during the rendering, there are commercial
UPS’s that allow you to add one, 2 or more external batteries to the unit,
to make sure there is enuf time for your needs.
It all really depends on how much money you want to spend to make sure the power stays on.
This one, like all the others are telling you, is to make sure you can shut down,
and have no clue about processes that take more than 10 minutes.
FCP X 10.2.2 – user since FCP 1.25
iMac mid 2011, MBA mid 2012
HVX-200, Shure wireless mic