18650 lithium-ion rechargeable battery type difference

It is the same whether the lithium battery is marked 3.7V or 4.2V. It's just that the manufacturer's label is different. 3.7V refers to the platform voltage (i.e. typical voltage) that is discharged during battery use, while 4.2V refers to the voltage when fully charged. The common rechargeable 18650 lithium battery has a voltage of 3.6 or 3.7v, and it is 4.2v when fully charged, which has little to do with the power (capacity). The mainstream capacity of 18650 batteries ranges from 1800mAh to 2600mAh, (18650 power battery capacity Most of them are 2200~2600mAh), and the mainstream capacity even has a capacity above 3500 or 4000mAh.

It is generally believed that when the no-load voltage of a lithium battery is lower than 3.0V, it is considered to be out of power (the specific value depends on the threshold value of the battery protection board, for example, it can be as low as 2.8V or 3.2V). Most lithium batteries cannot be discharged with the no-load voltage below 3.2V, otherwise over-discharge will damage the battery (generally, lithium batteries on the market are only used with protection boards, so over-discharge will also cause the protection board to fail to detect to the battery, making it impossible to charge the battery). 4.2V is the highest limit voltage for battery charging. It is generally believed that the lithium battery is fully charged when the no-load voltage is charged to 4.2V. During the battery charging process, the battery voltage gradually rises from 3.7V to 4.2V, and the lithium battery cannot be charged. Charge the no-load voltage to above 4.2V, otherwise it will damage the battery. This is the special place of lithium battery.