742 APU Start
 

With no external power connected and the main battery on, can you check the batt condition on the DC-meters panel. If so, is there a minimum voltage for APU start, or would one look for an ever so faint glow of the green DC fuel pump light perhaps indicating any life left in the batt. Or should I just forget about it and go have a brew.

Yes you can check APU Bat voltage, should be between 22-28.5 volts. I have managed to start the APU with 17 volts, closely monitoring start cycle.