The cell phone charger is 5V because there is a step-down circuit on the cell phone. Generally, the highest voltage of cell phone batteries is 4.2V and the lowest is 2.96V. The standard voltage is 3.7V. The reason for cell phone charger is to 5V is because the wires and circuit boards have resistance and the diode also has a voltage drop of 0.7 volts, so it totals about 5 volts. The charging limit voltage of 4.2V is the charging limit. voltage used by most lithium-ion batteries currently in use, or is called safe charging voltage. In theory, it can be loaded unlimitedly. Lithium batteries charged at 4.2 V are safe. When the voltage exceeds 4.2 V, the safety of lithium batteries begins to be compromised. decreases as the voltage increases. The higher the voltage, the more dangerous the battery andprone to fires and explosions. A good lithium battery can withstand a voltage of 4.8 to 5.0 V without catching fire or exploding. It might even explode at 4.5V, but 4.2V is basically safe. Therefore, the conventional charging limit voltage of lithium batteries is now 4.2 V, and some high-capacity batteries also have a charging limit voltage of 4.35 V.
The limit voltage of charging cell phone lithium ion batteries all 4.2V? And what is its connection with the charging voltage?
3.7V refers to the lowest voltage when the battery is exhausted.
It is generally believed that when the no-load voltage of a lithium battery is set to 3.7V, it is considered exhausted
< p>When discharging lithium batteries, the no-load voltage cannot be lowered below 3.7V, otherwise the battery will be damaged p>4.2 V is the highest limiting voltagehigh for battery charging.
It is generally believed that lithium batteries should be when the no-load voltage is charged to 4.2V, they are considered fully charged.
< p>During the battery charging process, the battery voltage gradually increases from 3.7V to 4.2VLithium batteries cannot be charged without charging. The voltage must be charged above 4.2V, otherwise the battery will be damaged
This is the special feature of lithium batteries
Lithium batteries marked 3.7 V or 4.2 V are the same thing. It's just that the manufacturer's labeling is different. 3.7V
refers to the platform voltage when the battery is discharged during use, while 4.2V refers to the voltage when fully charged.
The charging limit voltage of most organic lithium batteries is 4.2 V (depending on the mmaterial of the negative electrode, the charging voltage of a small number of lithium batteries is limited to 4.1V). The voltage of a lithium battery changes as it is discharged, and the voltage during charging also changes with charging time. When lithium batteries are in trickle charging (only if they are over discharged and the charger has a trickle charge function, which can protect over discharged batteries) and constant current charging, the voltage Battery capacity increases slowly as charging time passes. When the battery voltage reaches 4.2V, which is the charging limit voltage, charging enters the constant voltage charging stage. The battery voltage no longer increases and the charging current slowly decreases. Generally, the charger is set when the charging current is reduced to. the constant current charging current Stop charging when one tenth of the time ist reached. The charging voltage and limit voltage generally allow 1% error.