ALL Dark with BATT only??

[Guest vicleecy]

Hi Capts, I have been experiencing the following problems with V1.1 or previous version.1. With BATT ON and all buses connected, no display on PFD, ND...etc. So I have to connect the GND PWR or start the APU (without displaying the STAT page) and wait for the LCDs ON in god knows seconds later.2. Everytime I start the ENG, I hear number of "Woop Woop Woop Woop" warning ENG OIL PRESS LO. The similar things happen when shutting down the ENG. Of course when I ignore the above problems and start and wait the warnings to disappear after some minutes, my flight can be done flawlessly but it's just not that AS REAL AS I GET. May anyone suggests what did I do wrong? I started with the Cessna 172 on the active runway with Avionics, BATT, and ENG running. Then I click "Select Aircraft" to choose the T7. Is it so called the "Default Flight with Cassna172?" Thanks a lot for your advices, happy flying and safe landings.VictorHong Kong