I am using two batteries for my Phantom 3 Advanced when I fly my drone and I have a brand new unused spare battery for future use or sale. This new unused battery is being stored for almost 3 years now. Is this bad? I am afraid that if I regularly charge/discharge it like what I've been doing with my 2 used batteries, it will be considered 2nd hand already once I decide to sell it. Your advice will be greatly appreciated.