4.2V floating voltage. If you are sure that your 18650 battery has a built-in protection plate, you can charge it with a voltage of 5.39V. Once the battery is fully charged, the protection plate protection will automatically disconnect and will not cause battery overcharging. Typically, lithium polymer batteries will have protective plates. General cell phone batteries have built-in protective plates, and most cell phone chargers output a voltage of 5V.
04.2V is the highest limit voltage for battery charging. battery. The voltages of 18650 lithium batteries are generally 3.6V, 3.8V and 4.2V, which are much higher than the 1.2V voltage of nickel-cadmium and nickel-metal hydride batteries.
It is generally believed that a lithium battery is fully charged when its no-load voltage reaches 4.2 V. During the charging process ofthe battery, the battery voltage cannot gradually increase from 3.7V to 4.2V. charged without charging. The voltage must be charged above 4.2V, otherwise the battery will be damaged. This is the particularity of lithium batteries.
Lithium-ion batteries have the advantages of being lightweight, having a large capacity and having no memory effect. They are therefore widely used. Many digital devices use lithium-ion batteries as power sources, although they are relatively expensive. . The energy density of lithium-ion batteries is very high, their capacity is 1.5-2 times that of nickel-metal hydride batteries of the same weight, and their self-discharge rate is very low.
At present, the charging limit voltage of our commonly used lithium batteries is approximately 4.2 volts for a single cell. The rated operating voltage is approximately 3.6 volts. Thus, pFor a 12 volt lithium battery, it must be four single cell batteries connected in series. According to the basic principle of series connection of batteries, we can know that the maximum charging limit voltage of 4 cells should be 4.2 × 4, which is equivalent to about 16.8 volts. The nominal charging voltage is 3.6 × 4 = 14.4 volts.
The maximum voltage of the cell phone battery cannot exceed 5%. Otherwise, the battery will be damaged