21700 battery is the newest generation (2020) of cylindrical Li-ion rechargeable 3.7V cells.
21700 battery chargerfeaturing specially designed charging bays ready to accept (approximately) 70mm long Li-ion cells.
What is a 21700 battery?
The name 21700 comes from battery dimensions. Let’s break down the name of this battery: 21 is the diameter in millimeters (mm), and 70 is the length in millimeters (mm). Last digit, Zero (0) represents shape/type of the cell (battery) which in this case is Cylindrical. 21700 battery energy density is higher than in 18650. Important benefits and improvements are: Very high energy density ratio, Higher Capacity, High safety, High output, Lower production cost.
21700 batteries are available in two sizes and two types: 1. Protected (electronic advanced protection built-in) button top battery 2. Unprotected bare flat top cell (without any externally added safety protection)
Keep in mind that Protected 21700 battery is longer than 70 mm. It is because of added PCB (Printed Circuit Board and el. parts soldered to it) safety protection and button top (made of Nickel) that is welded to the bare battery cell.
The best 20700 Li-ion 3.7V batteries are also available, and 21700 backward compatible. 1mm smaller in diameter but very powerful.
