/diy/ - Do It Yourself

I'm looking to make a solar powered device and decided to use 18650s. Am I correct that I need both a charge circuit (with overcharge protection) and a discharge circuit (with overdischarge protection)? or do the 18650s usually come with the protections built in?

I would use something like image related to charge it, but I'm not sure if I can just connect my device to b+ and b- directly or if I need discharge protection. Either way I'm thinking about using a zener to ensure a minimum battery output voltage is used, as I will be powering a microcontroller.