battery empty after a while

[caxacix]

...i've tried electric_always.... and i tried electrical_always....
both did not help, i tried to put it at the beginning of the .cfg file, i tried it at the end, i really tried 1000 things...when i started a new flight with a default 737 and then changed over the "select aircraft" menu to the A300, it was working for a long while and i was happy already, but then after a half hour or so, in the middle of the flight, it was happening again...but i wonder why it takes much longer this way until power is cut off, than starting directly a flight with the A300???

Actually it wouldn't be a problem if the engines and Gen1 and Gen2 would feed the battery, but they don't, power is cut off even with running engines and generators turned on, the same for the APU and external power source.