Thanks for the help, Stevebfl and IMUL!
Problem seems to be the battery. Voltage across terms. was 7.55. Alt + volt. reg. is only a couple years old w/about 55,000 mi. on it.
I swapped another battery in there temporarily and I've been watching the voltage as I've been driving the car and no loss - so it appears alt. is ok.
The battery was 47 mos. old. Seems about right to go now given that 45-50 mos. has been my average w/batteries.