I had a flight yesterday, which was my 4th in total, and 2nd of the particular battery. I was hover around, going up to maybe 60 feet, taking a photo, then down again and some fast forward flight (Practising flighing boxes), when after the normal time, got the warning about battery. Quad was never more than 60 feet from me. So when I heard it, I decided to quickly go to 60 feet and take a final sunset photo, but as I got to 60 feet, in around.. maybe 20 seconds, the critical alarm piped up telling me it had to land in 10, 9, 8 etc. I managed to land, but the gap from 'Ok, battery getting low now', to 'Critical' was very very short. Is this normal? I thought I had the warnings at 30% for low, and 10% for critical, but the loss of 20% in 15 seconds?