As the characteristics of lithium-ion batteries and other rechargeable batteries are different, usually with a circuit board inside, many people do not understand the role of the circuit (some people may not know there are protective circuits in lithium), the following will lithium The characteristics of the li ion battery and the working principle of the protection circuit are described. Lithium batteries are divided into two types of batteries and secondary batteries, the current battery in the phone because of the small power consumption of the main use of non-rechargeable lithium battery, and the main battery in the phone because of the larger power consumption is the use of rechargeable two Secondary battery, that is, lithium-ion battery. Compared with nickel-cadmium and nickel-metal hydride batteries, lithium-ion battery has the following advantages:

1. high voltage, single-cell lithium-ion battery voltage can reach 3.6V, much higher than the nickel-cadmium and nickel-metal hydride battery 1.2V voltage.

2. the capacity density, the capacity density is nickel-metal hydride batteries or nickel-cadmium batteries 1.5-2.5 times.

3. long life, the normal use of its cycle life can reach more than 500 times.

4. no memory effect, before the charge does not have to empty the remaining power, easy to use.