These are my go-to rechargeable batteries. I have AA, AAA, C, D and 9V. I personally write their year of purchase with a magic marker. I find it helps me when choosing which ones to use more (I use the older ones more so as to save the fresher ones). So far I have some that are 8 years old and they're still holding their charge when stored. I can usually get about six to nine months with negligible voltage drop. Enjoy.