Three Air 2 batteries used both in a new Air 2 and new Air 2S. These batteries have less than 10 charge cycles each battery. I notice after using it, the batteries can remain hot after I put them back in my case with the drone. Its happened a few times now where I have the batteries and drone all packed up in its case and zipped up. And say a week later, I go to charge the batteries in preparing for usage the next day and the batteries and quite warm-semi hot to the touch. Feels like I just used the batteries even though they've been sitting unused in a case for a week. Whats causing this? Do these batteries need to be kept outside so it gets air circulation? Im worried that my batteries are defective.