I have now been caught out twice by a 4 minute (20%) low battery warning with an immediate RTH using my Avata - in the second case (and before I could react to stop it) the drone rose up into branches of a tree and careered through them towards the trunk, hit that and fell to the ground. Fortunately no damage done except to my nerves
I doubt that there is a parameter to change this though I shall check obviously. But perhaps be careful when the battery approaches 20% remaining
Other than that - what a fantastic experience flying the Avata is 