While I was thinking about the times, I thought I would suggest that if you do not have iosd or a way other than watching the lights on the phantom to know when it is time to land, you can buy 2 of these Low Voltage Alarms for $7
http://www.ebay.com/itm/350972901014?_t ... EBIDX%3AIT
They are priceless in my opinion. I always set mine for 3.7 and that gives me at least a minute to get back and land. If you are daring set it for 3.6 as that is about the time your first red lights will start flashing.
My brother was told about this when he bought his FC40 and he did not listen to his older brother lol !!! and sure enough he put an uncharged battery in and was flying over some water. He did not make it back in time and it cost ME hours of time to get it working again!!!!! Last time I will help for something that could have been avoided.
All you do it connect it to your balance plug. Just my thoughts so take it or leave it.
Grandpa Jake