I bought a fifty pack of these six years ago from a popular battery place online. Initially they worked great, and as they are indeed nearing the second half of their shelf life, I've noticed some things. In October I popped a pair in my Fenix TK 11 and it was in pulse (battery conserve) mode. The next four or five installs on LED and incan light seemed dimmer than normal. Last week our security system began alerting us to low batts in the downstairs smoke detector. Today the company called me at work to schedule a visit so when I got home I replaced the batteries. From the get go the alarm alerted to low batteries. A quick $13 trip later I had two new Energizer batteries installed. My lesson is not to buy a gross of these that may sit around. Around here my primary lights run rechargeable 123 batteries but I had higher expectations at six years.