Most 18650 cells are rated for between 300 and 500 cycles. That means your cell can charge up to 4.2 volts, and discharge down to 2.5 - 2.8 volts, a maximum of 300 to 500 times without too much much loss in performance. When an 18650 cell nears the end of its life, the performance loss is sudden and fast.Feb 12, 2015