How Long Does a Flashlight Battery Last? Cycle Life & Runtime Explained

Good branded lithium cells usually support 300–800 charge cycles before obvious capacity fade.
Low-cost unbranded cells may only last 100–200 cycles. After that, the battery runs out quickly, takes longer to charge and swells easily.
If the flashlight uses a built-in non-detachable battery, the whole torch becomes useless once the battery ages. That is another big after-sales headache.