I have 1979 6v92TAs with what appear original alternators. After sitting 3 weeks on hard w/o AC power, it was splashed and sat on AC power and charger for 24 hours, before I could get to it. Did not check voltages, but both engines started immediately. 90 minutes in to cruise back to home base, with all bridge electronics operating, I noticed radar CRT display wavering. Port voltmeter, which is house battery, showed about 9.5 volts. I shut off all electronics, except 1 VHF and voltmeter moved up to about 11 volts. Another 30 minutes and I was home. After plugging in to shore power and charger, voltmeter up to 12 volts in 1 hour and 14 volts in 3 hours. Over the last two years of ownership, I have noted 3-4 times this alternator at 12 volts at start-up and fast idel and going to its normal 15-16, only after advancing throttle beyond 1500 rpm.

I checked battery connections, water level and specific gravity of all cells and post connections on alternator; all OK. How can I check alternator output w/o damaging it or myself. It seems like on autos it damages ?diodes? to operate the alternator w/o battery connected.

Is removing alternator for a re-build a PITA or just usual grunt work?

Your words of wisdom and caution are always appreciated.