Newbie with warning buzzer sounding

[SFMEACH]

Well I am now officially a newbie since I took delivery on the bus I
bought back in January today (the person I bought the bus from stored
it for me until Spring). Everything seems fine except for a warning
buzzer that sounded for about 30-45 minutes in the dash area. The
previous owner said that the buzzer was sounding due to a discharged
genset battery. The genset worked fine with a jump but we did not run
it long enough for it to recharge. He said the buzzer would go off as
soon as the battery was fully discharged but in the meantime it would
sound the buzzer. All systems seemed fine so I drove it home with the
annoying buzzer buzzing. It finally went off except for a few
intermitant buzzes. Can anyone confirm the previous owner contention
regarding the genset battery? Oil temp and pressure were in the
normal range, engine temp was fine, the air pressure was about 125
PSI, the transmission temp was on the low side, just off the peg. I
hope I did not do the wrong thing by driving it.

Steve Meach
85 FC35
Paw Paw, MI