arduino - Is it okay to connect 2 lithium ion battery in parallel to a charger that can maintenance 4.2V? (more detail in post) - Electrical Engineering Stack Exchange
batteries - How to charge lithium ion battery in series and parallel? - Electrical Engineering Stack Exchange
DIY Li-ion battery: first connect cells in series, then in parallel - Endless Sphere
How to Wire Batteries in Parallel or Series – Dakota Lithium Batteries
Connecting Lithium Batteries In Parallel | My Generator