In a Nutshell
Our choice for the best 18650 battery is the Orbtronic cell. This battery has a high capacity (3100 mAh), and maintain their voltage until fully drained.
If you are looking for a good 18650 battery charger, I recommend this one: Tenergy 2-Channel 18650/14500 Li-ion Battery Charger (4.5 out of 5 stars from 97+ reviewers)
18650 batteries are rechargeable 3.7 volt lithium-ion batteries, and we think they are underrated! They usually have nondescript names, and come in generic packaging. 18650 batteries are mainly used in power high-performance flashlights, laser pointers, vaporizers and electric cars likes the Telsa Roadster.
Orbtronics makes a 18650 battery with a capacity of 3100 mAh, with a 675 Wh/L in energy density. The battery uses Panasonic’s “NNP (Nickel Oxide New Platform) Technology” — this increases the performance of the battery by incorporating a positive electrode made of nickel. You can read all about NNP Technology here (PDF file).
18650 Sizes and “Protected 18650s”
There has been a lot of confusion concerning the standard size of a 18650 battery. This is due to fact that some flashlight manufacturers like Nitecore produce flashlights that do not fit all 18650 batteries.
Panasonic, Sanyo, Samsung, LG are the top level 18650 cells manufacturers, and they make 18650 in the standard size, which is 18mm x 65mm.
Some third-party manufacturers, and companies in China make “protected” 18650 batteries, which incorporate a small circuit board, typically on the bottom of the battery, to stop overcharging and short circuiting. However, these batteries actually vary a bit from the standard 18650 size, and this becomes a problem when installing them in some equipment. However, standard “non-protected” batteries do not have this issue.