Due to its large capacity per unit density, 18650 lithium batteries are mostly used in laptop batteries. In addition, 18650 lithium batteries have very good stability at work and are widely used in various electronic fields: often used in high-end strong light Flashlights, portable power supplies, wireless data transmitters, electric thermal clothing and shoes, portable instruments, portable lighting equipment, portable printers, industrial instruments, medical instruments, etc.
So how to choose a high-quality 18650 lithium-ion battery? Choose the most suitable 18650 lithium battery according to our electrical equipment, such as the appropriate brand, voltage, capacity, continuous discharge rate, battery life, etc. The most important thing is to choose a battery with high safety.
1. Brand
Regarding brands, currently the more reliable ones include internationally renowned brands such as Sanyo, Samsung, SONY, and LG. Sanyo and LG focus on conventional products, and their main applications are bright flashlights, power banks, laptop batteries, etc. SONY is professional, focusing on power and high current. Taking VTC4 as an example, the discharge current can reach 30A, which can be easily used by electronic cigarettes, toys, etc.
2. Nominal capacity
The nominal capacity of the 18650 battery is related to the battery life, and the unit is "mAh". The higher the capacity, the stronger the battery life. For example, a 2800mAh battery can be continuously discharged for 2 hours with a current of 1.4A.
3. Continuous discharge current (CDR)
Continuous discharge capability is represented by C number. Continuous discharge current = Continuous discharge capability C number × capacity. For example, the capacity of an 18650 battery is 2800mAh, and the continuous discharge capacity is 0.5C, then the continuous discharge current = 1.4A. Discharging more than 1.4A for a long time will seriously affect the battery life, and may cause overheating, even burning, explosion, etc. .
5. Internal resistance
The internal resistance is the resistance of the battery itself. The smaller the internal resistance, the less consumption and stronger the discharge capacity. The internal resistance parameter is usually written on the battery introduction page. You should also pay attention to it when purchasing, and try not to Buy batteries with more than 100mΩ. When using multiple 18650 cells in series, be sure to buy batteries of the same brand and model, otherwise batteries with high internal resistance and low capacity will become shortcomings.
6. Temperature
Temperature is a major factor that affects the life of 18650 lithium batteries. The higher the temperature, the faster the battery will age. The higher the temperature, the greater the damage to the internal parts of the battery.
7. Pointed and flat ends
18650 lithium batteries are also divided into flat ends and pointed ends. In the picture below, the positive electrode on the left has a protruding part, which is a pointed end, and the positive electrode on the right, which has no protruding part, is a flat end. In general, I recommend purchasing pointed batteries to ensure compatibility with more devices and uses. Usually the positive and negative poles of flashlights are designed with springs and can be retracted. Both pointed and flat batteries can be used. But if you want to use flat-head batteries in series connection, the positive terminal of the flat head cannot contact the negative terminal of another battery.
8. With or without protective plate
The pointed head 18650 has a protective plate, and the flat head 18650 does not have a protective plate. The 18650 lithium battery with a protective plate is a few mm taller than the 18650 lithium battery without a protective plate, and the price is slightly more expensive, but it is safer and more versatile. The 18650 lithium battery with a protective plate can prevent the battery from over-discharging, which can cause Lithium batteries generate heat and may even burn or explode.
Among all 18650 lithium-ion batteries, LiSOCl2 has the highest energy density and a longest life of 15 to 20 years. This type of battery is particularly suitable for devices whose power supply current is small and relatively short. Due to the long battery life and low self-discharge rate, the environmental resistance of the battery is also very good.
