16340 VS 18650 battery

Not quite, while in principal they are the same, the 18650s have always gotten the most attention and development from manufacturers.

OVNI said:

The capacity specified in mAH is generally used to estimate runtime. Using two 16340 in series means runtime is still based on 650mAH but driving something @ 7.4V as opposed to using one 18650 rated at 3000mAH driving something else @ 3.7V . That is, the 18650 will 'run' roughly 4.5x longer than two 16340s.

Click to expand...

That would depend entirely on the design of the power supply/driver.

For something like a green or blue you would need a boost supply to run from a single cell, but a buck from two cells in series. With the correct driver the difference should not be that large really, although there are so many crappy cells on the market it is difficult to demonstrate this by now.

The 18650 cells were widely used in laptops until a few years ago, and some really good ones were on the market intended for that purpose.

Considering many laptops nowadays are too thin to house battery packs based on 18650s i predict this form factor will die out rather quickly, and only remain as something to use in flashlights, laser pointers and the odd powerbank. Sadly this will probably attract sub-par manufacturers even more, and we end up with 18650 cells that have perhaps 2 Ah capacity on a good day when the label claims 4.

Overstating the capacity grossly like that will attract attention in mainstream items like laptops, but probably not so much for loose cells sold on ebay or ali.

ApexsilverEVO said:

Not grave digging but just so other noobs like me know, 2x 16340 will produce 7.4V compared to 3.7V of 1x 18650. This can be a major factor when it come to powering the laser. The 18560 will yield much longer life however since it generally has much higher mAH i.e. 16340 = 650mAH and 18560 = 3000mAH

Click to expand...

Are you sure about that two 16340 batteries gives more output power because of 7.4 V?