How to check lithium battery？
2025-02-12
Lithium batteries are a common type of battery, widely used in mobile devices, power tools, electric vehicles and other fields. As the use time increases, the performance of lithium batteries may degrade or become damaged. In order to accurately evaluate the quality of lithium batteries, a variety of methods can be used to measure and test them.
This article will introduce in detail how to measure the quality of lithium batteries and lithium battery packs and related precautions.
1. Appearance inspection:
Appearance inspection is the first step to judge the quality of lithium batteries. Here are some points to pay attention to:
(1). Check the shell:
Observe whether the lithium battery shell has obvious damage, bending or cracks. Any physical damage may cause the battery performance to deteriorate or battery fluid to leak.
(2). Check the terminals:
Check whether the positive and negative terminals are clean and free of corrosion or oxidation. Corrosion or oxidation may affect the connection and current transmission between the battery and the device.
2. Voltage measurement:
Voltage measurement is a common method for evaluating the quality of lithium batteries. Here are some key steps:
(1).Connect Voltmeter to Battery Terminals
Use a digital voltmeter or multimeter to connect the positive and negative terminals to the positive and negative terminals of the battery.
(2).Measure the battery voltage.
Generally speaking, the nominal voltage of lithium batteries is 3.7 volts (V) or 3.6V.
(3).Compare to nominal voltage.
If the battery voltage is lower than 3.0V or significantly lower than the nominal voltage, it may indicate that the battery is exhausted or the battery is aging.
3. Internal resistance measurement:
Internal resistance measurement can reflect the performance status and health of lithium batteries. Here are some key steps:
(1). Connect to Internal Resistance Tester
Use a special internal resistance tester to connect the positive and negative poles to the tester.
(2). Measure the internal resistance
Internal resistance is a measure of the internal resistance of the battery. The internal resistance of a normal lithium battery should be between tens of milliohms (mΩ) and hundreds of milliohms (mΩ).
(3). Compare the measurements
If the internal resistance increases significantly, it may indicate aging, capacity loss, or damage to the battery.
4. Capacity measurement:
Capacity measurement is an important indicator for evaluating the quality and life of lithium batteri
Here are some key steps:
(1).Connect to Capacity Tester
Use a special capacity tester to connect the positive and negative poles to the tester.
(2).Take a capacity measurement
Capacity is a measure of the energy stored in a battery. Normal lithium battery capacity should be close to or slightly higher than the nominal capacity.
(3).Compare the measurements
A significant reduction in capacity may indicate aging, capacity loss, or damage to the battery.
5.Cycle test
(1).Test method:
After fully charging the lithium battery, connect it to the cycle test device and set the number of cycles and discharge load. After several cycle tests, observe whether the voltage at the end of battery discharge is normal.
(2).Judgment standard:
The normal voltage should generally be around 3.6V. The cycle test mainly focuses on the cycle life and discharge performance of the battery.
6.Discharge test
(1).Test method:
After fully charging the lithium battery, connect it to a specific load circuit and observe the change of the battery voltage over time. The longer the test time, the more accurate the result.
(2).Judgment standard:
The discharge test method mainly focuses on the discharge performance and energy density of the battery.
Lithium battery pack measurement method
Whether it is energy storage, electric vehicles or power tools, lithium batteries are rarely used alone. They are basically operated by battery packs composed of multiple lithium batteries connected in series or in parallel.
During the use of lithium battery packs, if one or more batteries are damaged, the performance of the entire battery pack will be reduced, and even the entire device will be adversely affected.
The following introduces three commonly used lithium battery pack detection methods.
1. Capacity detection method
The capacity detection method is to determine whether a battery is damaged by comparing the discharge capacity of each single cell in the lithium battery pack. The specific method is to discharge the lithium battery pack to the same voltage and then discharge the batteries one by one, record the discharge time and voltage of each battery and calculate its discharge capacity. The battery with the smaller remaining available discharge capacity is the battery that may be damaged.
2. Internal resistance detection method
The internal resistance detection method is to determine whether a battery is damaged by measuring the internal resistance of each single cell in the lithium battery pack. The specific method is to measure the internal resistance of each battery by a test instrument under a standard environment. Generally speaking, batteries with large internal resistance are prone to failure, such as failure to charge or discharge jitter.
3. Voltage difference detection method
The voltage difference detection method is to determine whether there is a damaged battery by comparing the voltage difference between each single cell in the lithium battery pack. The specific method is to fully charge the lithium battery pack and let it stand for a certain period of time, and then measure and compare the voltage of each battery to determine whether there is a damaged battery.
Other considerations
• Safety:
Lithium batteries have certain safety risks, especially when damaged or aged. When testing, ensure safe operation and follow relevant safety guidelines.
• Test environment:
When testing lithium batteries, it is necessary to ensure that the test environment is dry, clean and well ventilated to avoid unexpected accidents during the test.
• Avoid overcharging and discharging:
When testing the charging and discharging performance of lithium batteries, it is necessary to avoid overcharging and discharging to avoid negative effects on the life and performance of lithium batteries.
• Test result interpretation:
After the measurement, the measurement results need to be correctly interpreted. For uncertain or abnormal results, you can consider multiple tests or seek help from professionals.
In summary, through appearance inspection, voltage measurement, internal resistance measurement, capacity measurement, cycle test, discharge test, and paying attention to safety, test environment and avoiding overcharging and discharging, a more comprehensive evaluation of the quality of lithium batteries can be carried out.
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