Since it is imperative when planning auto missions to know your flight times I have been testing with stabilize/loiter hovers and measuring air time while I familiarize myself with the Arducopter platform.
I now have 17 full flights with respect to battery failsafe at 10.5 volts. I bought 3 batteries with the IRIS.
On these batteries the best hover time I can get is 10.5 to 11 minutes.
Yesterday I bought a more expensive Thunder Power RC G6 Pro Performance 3850mah 45C battery and a HI-Tech X1 MF balance charger. On the first flight with that battery I got 13 minutes hover/loiter. I hope to try it again today. Maybe it will get better after a couple of cycles. I only charged it with 1.9 amps for the first charge.
BTW - The $74 I spent on the charger was worth it. It charges the IRIS 3500 packs in an hour at 2 amps(well below 1C). The stock charger was taking 2.5 hours. it also displays the individual cell voltages and has a storage charge feature.
All battery tests were done with no payload. No legs, no camera, just like it comes out of the box.
I am curious to know what others are getting. The IRIS was advertised 10 to 15 minutes flight time. Assuming that it means 15 minutes with no payload and 10 minutes with legs and gimbal I would obviously like to be at 15 minutes with no payload. Doesn't seem possible as delivered.