Do you have any links on how the batteries are more than complex than a bundle of li-ion cells? Is the complexity in the systems to monitor voltage, temp, resis

Do you have any links on how the batteries are more than complex than a bundle of li-ion cells? Is the complexity in the systems to monitor voltage, temp, resistance and such of each cell and distribute load or outright fuse off weakened cells? I don't doubt you, but I would love to learn more.