They are indeed called 1865 cells too. The 0 at the end, according to some sources, indicates the cylinder form factor; I couldn't find a definitive reference f

They are indeed called 1865 cells too. The 0 at the end, according to some sources, indicates the cylinder form factor; I couldn't find a definitive reference for this though. But you will find articles and sources online referring to them as 1865 cells, like Wikipedia. "An 18650 battery[1] or 1865 cell[2] is a cylindrical lithium-ion battery common in electronic devices" https://en.m.wikipedia.org/wiki/18650_battery https://en.m.wikipedia.org/wiki/18650_battery I imagine Tesla calling their new battery a 4680 (opposed to a 46800) also leads to this usage.