I'm building a 3S 18650 Li-ion battery pack, which will be used for fast charging and discharging. Unfortunately, I can't find a 3S battery charging board that is commercially available. I found out that some people are connecting a BMS and powering 12,7-12.8V directly from a DC/DC converter to the whole pack, but I started wondering is that ok for the battery. Furthermore, I'm wondering is the balancing of the cells working in this direction, and what will happen when the battery pack is full? Is it healthy for the DC/DC to pump and the BMS to cut the supply?
I know that the proper charging IC will manage each cell voltage and either switch from CC to CV at some point to reduce the wear, but couldn't find other solution for now.