Shai Genis wrote on Aug 28^th, 2013 at 8:59pm:

Hey there, I'm getting the same issue. It is most certainly from the FSX menu. I have GSX, for those who know what it is, and when I requested refueling, the fuel truck showed up, it opened the default FSX fuel and payload screen, I put in the amount I need and closed. All the electrical power was gone, ground power didn't help, APU was not starting. Engines were off. I do have the electricalwaysavailable=1 and it did help before, from what I remember but it doesn't help anymore. Please, someone help us fix this bug! It's sad that I paid 54 bucks for this and have to deal with this issue. The plane is well designed and it's alright to fly, but this electrical bug is driving me and others nuts!

It is not because you are going into the menu in FSX. It can lose power just sitting there for about 8 minutes. :(

I also have and use GSX, and mine has suddenly started doing this (about a month ago). It happens during the boarding passenger and loading baggage phase. It's actually about 8 minutes after loading the 737 into FSX, so the GSX phase doesn't really matter, but since I set up the amount of fuel for the flight before I load it into FSX, it always happens during that phase of GSX.

Since my OP, on 24 April 2012 until about a month ago, the power stayed ON no matter what I did, so I always had power. I was NOT using electric_always_available=1, nor was I using unlimited/lengthened battery power via FSUIPC (registered version), so it must be being caused by something I have installed recently. I will have to go through all my receipts for products bought recently, to help with figuring out which one(s) it might be. :(

The electric_always_available=1 doesn't fix the problem, so for now, I've resorted to using lengthened battery power from within FSUIPC. :(