Check this thread on CPF. Note the runtime chart linked from post #636447 and the load test in linked from post #635735.

There is more discussion in this thread including links to other discussions.

Yes, the lithium AA cells typically start out about 1.7v, but they should quickly drop down to 1.5v. I think it is pretty rare for this to be a problem - mostly in cases where you have several cells in series.

-john