18650 Li-ion rechargeable battery is very popular because of its capacity and voltage. We encourage users to use rechargeable batteries because they reduce battery waste and saves Earth! We only have one Earth.

This is a 2-cell 18650 battery holder terminated with a standard 2.1mm DC Barrel Jack. Connect two 18650 batteries in series so the output voltage is rated at 7.4V (2 x 3.7V). This voltage is pretty good for Arduino which comes with a 5V or 3.3V voltage regulator. Of course not to forget all IoT and Robotic projects.