I have had some pretty hard landings and yet to break the battery lose in my Spirit. Lost it once in the woods and it didn't even pop the canopy.

Even when I was teaching myself how to fly my Aerobird, I only lost the battery once, and I had two drops from 150 feet due to a wing failure (I should have known not to fly that wing in 15 MPH wind) and a control line failure because I forgot to tighten the lock screw.

I guess I just do a better job of mounting the battery than most.