Hello!
gardner:
What you really want to know, is "are these batteries able to run my project, if I need them to?".
Exactly! 
However, as far as I know, the only reason why the batteries cannot supply enough power, is that they have too less voltage.
And this can be checked with reading their voltage.
So if the V_batt is enough (say 7V) then they can supply power for everything, otherwise they cannot.
This is how I would say, the batteries work like. Even if I don't know much about this, neither about the chemistry of them.