I finally decided to get a Multistar 4000 ma 10c battery for my P1 Phantom. I modified the battery opening to get it in. The Phantom has a Walkera G2D white plastic gimbal and Gopro white camera. Separate battery for gimbal. Still using stock props. I tested the quad with the 4000 ma battery and then a OEM 2200 ma battery. I really don't see a improvement in flight time. At least not worth the trouble as I can see. I'm sure the 10c rating may be an issue. I was flying easy. Maybe the weight is too much for a 10c battery. Maybe it would give much better performance with a bare Phantom 1. Now that was only the second charge on the 4000 ma battery. It might get better. I will test more. I will not modify my other 2 P1s just yet. Flight with 4000 battery...about 2 minute warm up and compass calibration. About 8 minute flight till red battery warning. I landed it...shut off camera...took off again and after about a minute got the red battery warning again and landed. The battery seems to come back up a bit. . Temp was about 33 degrees F. The 2200 ma battery was about the same time although the wind did pick up. Flying was in GPS. I just don't see a great gain. Others have said the 4000 battery gave much better time. Thoughts??