What's mean Protection Circuits (3)?

What's mean Protection Circuits (3)? What's mean Protection Circuits (3)? Each parallel string of cells of a Li-ion pack needs independent voltage monitoring. The more cells that are connected in series, the more complex the protection circuit becomes. Four cells in series is the practical limit for commercial applications. The internal protection circuit of a mobile phone while in the ON position has a resistance of 50 to 100 mW. The circuit normally consists of two switches connected in series. One is responsible for high cut-off, the other for low cut-off. The combined resistance of these two devices virtually doubles the internal resistance of a battery pack, especially if only one cell is used. View the rest of this article