Laptp batteries have a circuit board that talks to the laptop via SMBUS communication. It's called a "Smart battery" - It measures voltages, current, temperature etc. It does not have ability to balance the cells. The cells are matched at the factory for internal resistance so they will work together.
Charging is done by a dedicated circuitry in the laptop as well.
Of course I am referring to old laptops, but in those I have seen the battery has a connector which brings out all the connections between the cells and the laptop proper contains the balancing circuitry.