yep ... you can safely use 80% of your battery power. If you are not sure what that is .... run your battery for 4 minutes using your normal flying style.... and then do a fast charge. take note of how many MAH you have added to the battery to get to full charge. what ever that is divide by the flight time and you will have the average MAH per minute used. Then you can safely work out how many actual minutes you can used that battery to get to your 80% draw down. - Hope this helps