How To Test The Capacity Of Lithium Battery?

How to test the capacity of lithium batteries? I believe that many friends have many methods. One of the main reasons we test the capacity of lithium batteries is to see if the manufacturer has a false standard capacity, to see whether the battery products of the battery manufacturer are reliable, and to see the lithium battery Whether the actual capacity can meet the power parameter requirements of the designed product. Here are a few simpler lithium battery capacity test methods.

1. The method of actual use to test the capacity of lithium batteries

Although this method is relatively simple, it requires relatively high operational requirements. The specific operations are as follows:

(1) Prepare a current flow meter and an electrical appliance marked with rated working current and voltage requirements. For example, the rated working current of the product is 2A, the symbol is I, the voltage is 12V, and the symbol is V;

(2) Buy one or several 12V lithium batteries of different brands, with a discharge current of 2A or more, and the battery capacity should be the same, if they are all 6000mAh, the symbol is C;

(3) Connect the battery to the electrical appliance and install a current flow meter to allow the electrical appliance to work at the rated current and voltage until the electrical appliance becomes weak or abnormal. If the working time is T (the difficulty lies in the control The rated working efficiency of electrical appliances is more difficult);

Then you can test the battery capacity of the lithium battery: C=IT

2. Use formula to calculate and estimate lithium battery capacity

The capacity of a lithium battery is related to the model size and depends on the thickness, width and length of the battery. It is also related to the material and size of the battery. The actual calculation formula of polymer lithium battery capacity is very complicated, and the relationship with volume is not linear. Many factors need to be considered, such as different materials, which have a great impact on the actual capacity. The larger the size, the larger the capacity/volume ratio.

To quickly estimate the capacity of a polymer battery, the commonly used estimation formula (for estimation only):

Capacity = thickness * width * length * K (K unit is mah/mm3)

The range of K value is (0.07~0.11). The K value depends on the material industry and the size of the capacity. The larger the capacity, the larger the K value, the smaller the capacity, and the smaller the K value (it can be understood as the larger the size, the greater the K value Big). In actual calculations, the K value can be set to 0.1 by default. For example, 103450LP (thickness 10mm, width 34mm, length 50mm), calculated capacity=10*34*50*0.1=1700, the actual capacity is above 1800mah; for example, 603048LP (thickness 6mm, width 30mm, length 48mm), calculated capacity=6* 30*48*0.1=864, the actual capacity can be 900mah.

The above are two simple and commonly used lithium battery capacity test methods. From the perspective of accuracy, it is obvious that the lithium battery capacity tested by the first method is relatively accurate, while the second method is worse. After all, it is theoretical. It is estimated that there are many factors that are affected, and in terms of convenience, it is obvious that the second method is more convenient, because basically no tools are needed, as long as you know the volume of the lithium battery and the value of K (generally different manufacturers will have different The value of k is mainly caused by the difference in the process level and material formula of the lithium battery produced by the battery manufacturer), and the approximate capacity of the lithium battery can be quickly estimated.