Lithium battery (Li-ion, Lithium Ion Battery): Lithium-ion batteries have the advantages of light weight, high capacity, and no memory effect, and thus are commonly used – many digital devices use lithium-ion batteries as a power source, although they are relatively expensive. The energy density of lithium-ion batteries is very high, and its capacity is 1.5 to 2 times that of NiMH batteries of the same weight, and has a very low self-discharge rate. In addition, lithium-ion batteries have almost no “memory effect” and do not contain toxic substances and other advantages is also an important reason for its widespread use. Please also note that lithium batteries are usually marked with 4.2V lithiumion battery or 4.2V lithium secondary battery or 4.2V lithiumion rechargeable battery on the outside.

18650 lithium battery
18650 is the originator of lithium-ion battery – is a standard lithium-ion battery model set by the Japanese SONY company in order to save costs, 18 means the diameter of 18mm, 65 means the length of 65mm, 0 means a cylindrical battery. 18650 means, 18mm diameter, 65mm long. And the model number of No. 5 battery is 14500, 14 mm in diameter and 50 mm in length. General 18650 battery is used more in industry, civilian use is very little, commonly used in laptop batteries and high-end flashlights.

Common 18650 batteries are divided into lithium-ion batteries, lithium iron phosphate batteries. Lithium-ion battery voltage for the nominal voltage of 3.7v, charging cut-off voltage of 4.2v, lithium iron phosphate battery nominal voltage of 3.2V, charging cut-off voltage of 3.6v, capacity is usually 1200mAh-3350mAh, common capacity is 2200mAh-2600mAh. 18650 lithium battery life theory for the cycle charge 1000 times.

18650 Li-ion battery is mostly used in laptop batteries because of its high capacity per unit density. In addition, 18650 Li-ion battery is widely used in electronic fields because of its excellent stability in work: commonly used in high-grade flashlight, portable power supply, wireless data transmitter, electric warm clothes and shoes, portable instruments, portable lighting equipment, portable printer, industrial instruments, medical instruments, etc. medical instruments, etc.

Li-ion battery marked 3.7V or 4.2V are the same. 3.7V refers to the platform voltage (i.e., typical voltage) during the use of the battery discharge, while 4.2 volts refers to the voltage when charging a full charge. Common rechargeable 18650 lithium battery, voltage is marked 3.6 or 3.7v, 4.2v when fully charged, which has little to do with the power (capacity), 18650 battery mainstream capacity from 1800mAh to 2600mAh, (18650 power battery capacity is mostly in 2200 ~ 2600mAh), the mainstream capacity is even marked 3500 or 4000mAh or more are available.

It is generally believed that the no-load voltage of Li-ion battery will be below 3.0V and the electricity will be used up (the specific value needs to depend on the threshold value of the battery protection board, for example, there are as low as 2.8V, there are also 3.2V). Most lithium batteries can not be discharged to the no-load voltage of 3.2V or less, otherwise excessive discharge will damage the battery (the general market lithium batteries are basically used with a protection plate, so excessive discharge will also lead to the protection plate can not detect the battery, thus unable to charge the battery). 4.2V is the maximum limit of battery charging voltage, generally considered to be the no-load voltage of lithium batteries charged to 4.2V on the electricity Full, the battery charging process, the battery voltage at 3.7V gradually rise to 4.2V, lithium battery charging can not be charged to more than 4.2V no-load voltage, otherwise it will also damage the battery, which is the special place of lithium batteries.

Advantages

1. Large capacity 18650 lithium battery capacity is generally between 1200mah ~ 3600mah, while the general battery capacity is only about 800mah, if combined into 18650 lithium battery pack, that 18650 lithium battery pack is casually can break through the 5000mah.

2. Long life 18650 lithium battery life is very long, the normal use of the cycle life of up to 500 times, is more than twice the ordinary battery.

3. High safety performance 18650 lithium battery safety performance, in order to prevent the battery short circuit phenomenon, 18650 lithium battery positive and negative poles are separated. So the possibility of short circuit has been reduced to the extreme. You can add a protection plate to avoid overcharging and overdischarging the battery, which can also extend the service life of the battery.

4. High voltage 18650 lithium battery voltage is generally at 3.6V, 3.8V and 4.2V, much higher than the 1.2V voltage of NiCd and NiMH batteries.

5. No memory effect No need to empty the remaining power before charging, easy to use.

6. Small internal resistance: The internal resistance of polymer cells is smaller than that of general liquid cells, and the internal resistance of domestic polymer cells can even be less than 35mΩ, which greatly reduces the battery’s self-consumption and extends the standby time of cell phones, and can completely reach the level of international standards. This kind of polymer lithium battery that supports large discharge current is ideal for remote control models, becoming the most promising alternative to NiMH batteries.