The method is as follows:
1. Connect the Arduino development board and LCD display, and connect them according to the pin connection instructions.
2. Connect the Arduino development board and the lithium battery charge and discharge module, ensuring that the positive and negative poles are correctly connected.
3. Connect a known resistor to the analog input pin of the Arduino development board to measure the lithium battery voltage.
4. Write the Arduino code to measure the voltage through the analog input pin and display it on the LCD screen.
5. Calculate the internal resistance via code and use the measured voltage and known resistance to calculate the internal resistance value according to Ohm's law.
6. Install the battery clip to connect the lithium battery to be tested.
7. Write code so Arduino can automatically change the stateat operation of the battery charge and discharge module for internal resistance testing.
8. During the test, fix the two poles of the lithium battery. Arduino will automatically charge and discharge the battery, measure the voltage, calculate the internal resistance value and display it on the LCD screen.
How to measure the internal resistance of lithium batteries, please find the method
Lithium batteries have no capacity or internal resistance and require internal resistance testers and special ability testers.
The internal resistance of 18650 is generally between 20 and 65 milliohms, and a multimeter can only measure voltage.
18650 is the origin of lithium-ion batteries - the Japanese company SONY wanted to reduce costs at the time, a standard lithium-ion battery model is defined, where 18 means a diameter of 18 mm, 65 means a length of 65 mm and0 means a cylindrical battery.
Common 18650 batteries are divided into lithium ion batteries and lithium iron phosphate batteries. The rated voltage of lithium ion battery is 3.7V, the charging cutoff voltage is 4.2V, the rated voltage of lithium iron phosphate battery is 3.2V, the cutoff voltage charging is 3.6V, capacity is generally 1200mAh. 3000mAh, common capacity is 2200mAh-2600mAh.
Is there a simple method to measure the internal resistance of an 18650 battery?
You can choose an external resistor, such as 100 ohms, first open the circuit and measure the electromotive force of the battery, for example to obtain 10V, and then connect the resistor to the lithium battery , then use a multimeter to measure the voltage of the two electric shocks of the battery, for example 9V. Divide the resulting voltage 9V by 100 to get the total circuit current 9/100.Obviously 10-9=1 is the voltage inside. internal resistance of the battery. Divide the voltage 1 of the internal resistance by the total current (9/100 ), we get the internal resistance of the battery = 100/9 ohms.
You can choose. Resistance at will. If the measured value is too small, you can change the selected resistance.
1. Compared with new batteries, after using them for a period of time, new batteries do not feel any significant change in temperature, while old batteries gradually become warmer. Keep it within a certain warm temperature range and using it for a shorter period indicates that the internal resistance has increased, but it is not discarded and can continue to be used;
2 When used under the same conditions. , the battery temperature increases. Soon she gets hot and she unloadsquickly. This means that the internal resistance of the lithium battery has increased to the point of being scrapped.
Internal resistance of lithium battery
Generally, the unit is mΩ For more advanced lithium battery manufacturers, the internal resistance of the battery at the output of the The factory is between 0.3 mΩ and 30 mΩ. depends on the lithium battery cell. Depends on size. The internal resistance of lithium batteries increases with use. So, what is the internal resistance of lithium batteries before they are discarded? It is difficult to give this precise figure, but you can make some judgment based on the battery phenomenon.