Extra Batteries

[bern]

I have seen several advertisements for holders for extra batteries on the Phantom; as many as 2 extra. Also for external holders for 3300maH batteries. Are these effective, or does the extra weight just use up the extra energy?

 

[fizzviic]

I am flying dual batteries and I get about 1.5 X the flight time over a single battery. I run a fairly consistent 12 minutes to the red warning light (standard setting) verses about 8 minutes with a single battery. I'm pretty heavy, a little over 1200 grams with GoPro full housing, and modified landing gear.