1983 Honda CB550SC has intermittent charging issues - what's wrong?

1983 Honda CB550SC has intermittent charging issues - what's wrong?

Added (1). After charging my battery (Li Ion, Battery Tender brand) I usually don't have any issues. I last had to do this about 2 weeks ago and I took it out for a ride today and a couple minutes in it just crapped out. Was fortunate enough to have someone come jump me and I rode home with high RPMs. Shut it off, got my multimeter out and started it up again. Started around 10.6v at idle and then was making its way down to the 8v range and just shut off. What is going on here?

Have the battery charged and 'load tested'.
You may have charging problems but best to check first things first.

Adding to what Chris said, A weak battery will not have the strength to accept or hold a charge.
The bike's charging system does not supply power to run the engine.
The battery runs the engine.
The charging system recharges the battery, as it is being drained by the bike's electrical system.
When the battery drains out of power, the engine goes dead, until you charge the battery again.
Charge the battery and have it "load tested"