Appearance inspection
If the appearance is damaged or rusty
Voltage judgment
Use a multimeter to test the voltage of the battery. Normal voltage is around 3.7. v, such that if it is less than 2.7 V, more than 90% of the probability is bad.
Battery capacity test
If you have a charger with a capacity display, you can check the real status of the battery. Charging capacity, generally the capacity of 18650 is between 2200-2800 mAh. If the displayed capacity is low, it means that the battery capacity is relatively low. If the capacity is relatively small, it can basically be eliminated. scrap
< p>If you don't have professional equipment, you can also use resistors, light bulbs, etc. who know the power to calculate the power. The power of 18650 (taking 2400 mAh as an example) is. calculated by the formule about 3.7*2.4=8.88whWhat should you pay attention to when purchasing lithium batteries?
Current lithium-ion battery technology can be roughly divided into two types according to the outer packaging: metal shells and flexible composite film packaging, which are the two types mentioned by the poster. The metal shells are then divided. in aluminum hulls and steel hulls, the poster mentions One is a steel hull. The electrolytes inside are all liquid - flexible composite film packaging is divided into two types: polymer lithium-ion batteries and liquid lithium-ion batteries according to the positive and negative electrode materials and electrolytes inside . Overall, metal. One form of shell and soft pack is called a liquid lithium-ion battery. The other form of soft pack is called a lithium-ion polymer battery. electrode materials ppositive and negative of the liquid lithium-ion battery and the polymer lithium-ion battery are made of different materials than the electrolyte. Let's talk about the difference. The soft shell is that it will expand once it is inflated a little. Liquid and polymer shells are not easy to use in lithium polymer batteries. Safety performance is slightly better than liquid. will not explode. Due to the energy density, the soft shell is much thinner than the metal shell, especially when it is large, so after being made into a battery, with the same volume, the capacity of the soft shell. will be bigger. The same thing is that they all belong to the chemical battery system of lithium-ion batteries. They are essentially the same.
What are the testing standards for lithium batteries?
Lithium batteries are increasingly the first choicemore people, but you should pay attention to them when purchasing them. Appearance refers to the appearance, construction, size and finish of the lithium battery. Check whether the shell's seams are wide, whether there are any burrs, whether there are oil stains, and whether it feels good to the touch. Advanced technology is very comfortable to the touch. After polishing, the material polished with rubber oil not only feels good. good, but also has strong insulating properties.
2. Check to see if the capacity is clearly marked.
Lithium batteries without clearly marked capacity are likely to be junk batteries reassembled using substandard battery cells or recycled battery cells. The market is flooded with many cheap lithium batteries, made from recycled battery cells or dismantled cells. Although their price ischeap, their life is short. The quality is unstable, and careless use may damage the equipment or even cause an explosion.
3. Look at the protection circuit
The characteristics of lithium batteries determine that lithium batteries should be equipped with a protection board to prevent overcharge, overdischarge, short circuit, etc. lithium battery. Lithium batteries with protective plates pose a risk of deformation, leakage and explosion. Facing fierce price competition, various battery packaging manufacturers are looking for cheaper protection circuits, or simply omitting this device, leaving the market flooded with lithium batteries with the risk of explosion. Of course, in fact, consumers cannot tell whether there is a protective circuit board from the appearance, so it is better to choose a reputable merchant to purchase it.
4. Look at the brand
There are many brands of lithium batteries, but the quality is difficult to determine from appearance. In this case, everyone should do more research before choosing and check the manufacturer's information online. Generally speaking, professional manufacturers are more reliable than small workshops, and manufacturers who have been in business for a long time are more trustworthy than those who have just entered the field.
Life test GB/T18287 standard for lithium batteries, IEC The standard life test for lithium batteries is stipulated as follows: ?
After the battery is discharged to 3.0V /unit at 0.2 C, charge it with constant current and constant voltage 1 C. to 4.2 V with cut-off current 20 mA and leave it for 1 hour then discharge it to 0, 2 C to 3.0 V (one cycle). After repeated cycles 500 times, the capacity should be greater than 60% of the capinitial acity.
The IEC states that the standard life test for nickel-cadmium and nickel-metal hydride batteries is: after the battery is discharged to 1.0 V/unit at 0.2 C. < /p>
According to the national standard for lithium batteries: GB/T18287-2000, the test items of lithium batteries include appearance, discharge performance, high and low temperature performance, capacity charge retention, life cycle life; vibration resistance and collision resistance, environmental adaptability with free fall resistance; safety performance in overload protection, overvoltage protection and short circuit protection; safety performance in resistance to heavy object impacts, thermal shock, overload and short-circuit storage performance; etc. The following focuses on the conditions and standardsTest es for discharge performance, high and low temperature performance, service life and protection against overcharge, overdischarge and short circuit.