Make a 18650 battery charger, Li-ion battery charge controller circuit - YouTube | Battery charger, Lithium battery charger, Batteries diy
Is there way to construct an 18650 battery pack with built-in balance charging? Or is balancing not very necessary? - Electrical Engineering Stack Exchange
How to charge two 18650s in series without a middle connection? - Electrical Engineering Stack Exchange
18650 2600mAh Battery Datasheet and Working - Homemade Circuit Projects