Store then at a lower voltage to prolong thier life. I have too many Lions of sizes that I don't use regularly also. I have found that 3.8V works best for me. When they self discharge to about 3.7V I top them off and run them back down to ~3.8V'ish before putting them back into storage. Got any RCR123s or 18650s you are looking get rid of, just PM me.