Hi!
I'm about to build a portable bluetooth speaker, which i want to be supplied by three Li-Ion 18650 in series.
I've been reading about some issues connected with charging these batteries. As a beginner, I ask for some advices about charging them in the most friendly way - by the popular 5V power supply. These are things I have:
- Step-UP buck converter, which can be used to acces 12V
- 2x TP4056 charging modules (buying another is optional)
- 2x 2S protection modules
- Arduino Pro Mini/ Nano
I'm full of hope, these things can do the job. I thought about controlling voltage on each cell with Arduino (is it even possible?). Also, I've seen 3xTP4056 controlling each cell somwhere. I don't really know when do i need protection board and when i don't. Can i use 2S board for 1 cell?
Please, help me finish my project.
Best Regards!

 

Welcome to AAC!

As a beginner, I ask for some advices about charging them in the most friendly way - by the popular 5V power supply.

For best performance, you need to use a charging profile appropriate for the battery chemistry. Improper charging can cause batteries to explode or catch on fire.

http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

 

Yep, I'm aware of these aspects, but the point is i don't want to use a traditional method.
I think Arduino could be a good solution as a BMS and balancer. No doubt we can read the voltage on each cell. Both while charging and powering.
When it comes to a charger, i hope some 0,5C (CC/CV) module will be available on Aliexpress.
What are your thoughts about this idea of Arduino? If you find it reasonable, please share some advices. If not, please reply too.