So at the end of each summer drone flying season what is the best suggested battery charge level for safe storage. I saw some where that you should only charge your lithium polymer drone batteries to about the 50% level to avoid any possible expanding damage. Is that correct. I had fully charged my Eachine EX4 2 batteries at the end of last year's season, and they both expanded a lot and pushed off the case cover. So much swelling then made those batteries dangerous and not usable. Okay thanks.