I don't plan on flying the bird for a couple of months. The last time I had it out was approx Feb. 2 2016. At that time I flew it till the go app said the battery level was low. When I push the button on the battery, I see one solid green light. According to the manual, this means the charge is between 30 and 40 percent. Is it ok to store the battery at this level or must I charge it to the recommended 65 percent level? Thanks. Jim B.