Captain Sim wrote on Apr 25^th, 2012 at 12:00am:

Markoz wrote on Apr 24th, 2012 at 4:01pm: I was using the 737-200 and I was not using the APU or External Power/Bleed Air. After a while, the power went out. The battery had died. 1. Does this happens every flight? 2. Are you sure the generators are ON? 3. What happens if you ARE using the the APU or External Power for the startup?

It did happen every time unless I started the APU before I clicked on any FSX menu items. the APU gen was on.
I tried using the external power and air start when this happens but no joy. I tried the same as Markoz, and the default aircraft with engines running and still no battery power and the engines would not start. I even tried the CTRL E... nothing. Shut down FSX and re-started. No issues everything was working. This happened a couple of times until I put in the electric_always_available=1 line in the config. I know it's not realistic or a fix.