So I have this Phantom. It has a Battery. Lasts around 20 minutes or so. Also have a car charger to charge away from home. I am in the market for an extra battery or three. My question is how long of a cool down time is sufficient, adequate, and or responsible for the longevity of the drone's precious brushless motors and other electrical components onboard? I want to make sure I allow enough cooldown time between batteries as not to provoke the premature demise of my most beloved quadcopter. Is this necessary or can the drone dissipate heat something like the 100% duty cycle of a car's cooling system? Also what is a reasonable price for a genuine DJI phantom battery?