Why are AA rechargeable batteries only 1.2 volts instead of 1.5 volts?

Answer 1

Has to do with the chemicals used inside the battery - they are different than regular AAs... usually NOT a problem except in some voltage-sensitive equipment using several AAs. As a service technician, the only time I came across this as a problem was in an elaborate remote control where voltage mattered more than current available in the batteries.