Originally Posted by
pauschl
I have a CREE XM-L T6 1800Lm flashlight I just bought. I've been using 3 aaa NiMH batteries with the adapter. The flashlight will also work with 1 18650 with an included adapter, or 1 16650 with no adapter. Will I see better performance if I use an 18650 or a 26650? Recommendations?
Yes, you will see better performance.
The brightness will be approximately the same as the voltage of 3xAAA vs 1 lithium ion cell is about the same. However, the 18650 probably has three times the energy of 3xAAA cells, so 3x the runtime. It can also handle higher discharge rates better, so it might be a bit brighter and have even more than 3x the runtime.
The 26650 has even higher capacity than the 18650, so even more runtime. Same voltage, so same brightness.
And all that said, there's no way that a 3xAAA powered light is going to put out 1800 lumens. Could it be 180 lumens instead?
As for a recommendation, go for the lithium ion battery. It's a lot more convenient (only one battery to deal with rather than three in their little holder) and it lasts a lot longer. As for which one, that depends on you. Do you already have some of one kind?