Lithionics told me at the last rally that I should cycle the batteries. Discharge the batteries to their reserve voltage (i.e. until they quit working) and then recharge them. He suggested I run the a/c on battery until it quit as a quick way to run them down. This seems to have worked for me as my batteries now show similar life remaining.
The rep said that the batteries don't really know their discharge state and use an algorithm based on recharge time, usage, etc. and sometimes get out of sync.
There is another discussion about this here.