Questions about Nitecore 18650 Rechargeable battery

No, this must be purchased separately. Z. E.g. NITECORE Digicharger D2

Hello May I ask what kind of torch you have ?

No. This one is compatible :) LED Lenser Akku CR18650

neither, is a special measure.

That is SO not quite correct! 18650 is indeed a standard with fixed masses, but this refers purely to the cell. If you were to measure only the cell of this Nitecore battery, it would have exactly the 18mm diameter and 65mm length. But here is exactly the point. Most of these "branded" batteries have a so-called protection PCB "built in", which protects the cell from too deep discharging, too high charging/discharging currents and too high charging voltage. This is actually a good thing. But this PCB also needs space, which makes the "overall construct" of the battery longer than the norm. Depending on the PCB used, sometimes a little more, sometimes a little less. But logically, the standard is always exceeded with PCBs. However, the whole thing is not the end of the world, as this circumstance is explained everywhere. So you just have to ask yourself, do I want to use the unprotected cells that meet the standard dimensions and take the risk of a defect or fire? Or is safety worth the few mm? Yes, Li-Ion batteries can quickly become hot and burn if used incorrectly. And burning Li-Ion batteries cannot be extinguished so quickly ;) But it is written in every data sheet of every battery how long it is. https://www.nitecorestore.com/Nitecore-LN1834-18650-Battery-p/bat-18650-3400-nite-nl189.htm