One of my club members recently had a total loss of an expensive giant scale gasoline powered model a few days ago. The model went straight in from 400 feet. It didn't take long to determine what had happened. The transmitter battery had a catastrophic failure, where every one of its 8 cells had failed.
So, I put together this article in our club newsletter describing what happened, and making suggestions for appropriate battery power for the receivers and servos in our model airplanes.
This article is aimed at those modelers that fly giant scale models with separate receiver battery supplies for their model airplanes. There may be some readers of this thread that do use separate batteries rather than a uBEC for receiver power.
As for me, in my giant scale models, they are equipped with a Castle Creations 10 Amp uBEC, along with a backup two cell 2300 Mah A123 pack, with diodes to isolate the A123 pack from the uBEC.
Hope this is useful.