Battery Management System 18650

I will suggest to buy the pure nickel.
Battery management system 18650. In general two types of nickel strips are available in the market. Developed over the last three years his open source system allows users to assemble large 18650 battery packs for electric vehicles or home energy storage complete with integrated intelligent. Whether it be a 18650 bms solar bms or one for electric vehicles they all have a similar function. Nickel plated steel strips and pure nickel strips.
A bms is a pcb circuit board that provides protection monitoring balancing and other high level functionality for a battery pack. To make the battery pack you have to to connect the 18650 cells together by means of nickel strips or thick wire generally nickel strips are widely used for this. So i have been searching the internet and books on how to design a battery management system for a 4s configuration of 18650 batteries.