18650 Lithium ion batteries Mesuring Method

- Dec 23, 2018 -

Measuring method for capacity of 18650 lithium ion batteries


With the development of society, energy storage lithium-ion batteries play an increasingly important role in society. By the end of 2015, the installed capacity of energy storage in China was 22.8 GW, accounting for about 1.7% of the total installed capacity in China. It is expected that by 2025, the energy storage lithium-ion battery industry will achieve large-scale development, form a relatively complete industrial system, and become a new economic growth point in the energy field. At present, there are three main applications in the energy storage lithium-ion battery market: power storage, household energy storage and base station energy storage. The backup power supply of communication base station accounts for a large proportion, accounting for nearly half of the total energy storage lithium-ion battery market. The capacity of lithium ion batteries is the premise of how long the equipment can be used. So do friends know how to measure the capacity of lithium-ion batteries more accurately? Generally, there are some deviations between the nominal capacity and the actual capacity of the manufacturers. Understand the measuring methods of 18650 lithium-ion battery capacity. Let's learn together below.


1. Measuring methods for capacity of 18650 lithium-ion batteries


1). Simple method of constant resistance discharge. You need to use a multimeter and a high-power resistor. First of all, you can fill it in your seat, such as on the computer or on your mobile phone. Connecting the full load of lithium ion batteries with this resistor can usually be a 10 ohm 5W cement resistor to discharge to a voltage below 2.75V. This method is relatively simple to obtain the total discharge time capacity = 0.37A* time, but there are some errors.


2). Normal method: Using lithium-ion battery capacity tester, first charge to 4.20V, then put aside constant current discharge for one hour. Arbitration method is 0.2 times, such as 1000 mAh capacity, then discharge to 2.75V by 200 mA constant current discharge. Calculating time * constant current = lithium-ion battery capacity is in accordance with the national standard 18287 lithium-ion battery. If it is a Ni-MH-Li-ion battery, the same is true, but the charging method is not constant voltage, and the discharge is up to 1.0V each section of this method requires special equipment.


II. Measuring Method of Capacity of 18650 Lithium-Lithium Ion Battery


Method 1:


Professional lithium-ion battery compartment


For personal use, find an adjustable load resistance and a Current-Adjustable DC power supply to calculate the capacity of lithium-ion batteries by charging and discharging time.


Charging current * charging time = lithium-ion battery capacity (charging from 2.7V or 3.0V to 4.2V)

or Discharge current x discharge time = lithium ion battery capacity (from 4.2V to 2.7V or 3.0V)


Method two:


The first step is to charge the lithium-ion battery to the rated voltage, usually 4.2V.


The second step is to discharge lithium-ion batteries to the rated voltage, and record the amount of discharge, the voltage is generally 3.0V.


The third step is to charge the lithium-ion batteries to normal volume, which is generally set to 3.8V-4.0V.


The capacity recorded in the second step is the capacity of lithium-ion batteries.


Method three:


The integral function of the power meter can be used to measure the capacity of lithium-ion batteries required by the equipment. I usually use the PA310 power meter to measure the capacity of lithium-ion batteries. After measuring the capacity, I choose the lithium-ion batteries with larger capacity for the use of the equipment.


The procedure of capacity measurement for 18650 lithium-ion batteries is roughly the same. Normally, the capacity of 18650 lithium-ion batteries will not exceed 3100 mAh (the limit is 3400 mAh), any excess is fake and inferior goods, there is a risk of explosion. The author is buying a brand of flashlight. The lithium-ion battery attached is 5000 mAh, which is obviously false.