The increased use of lithium-ion battery-powered devices has created a demand for high levels of precision and quality to support a wide range of applications. One evaluation test method utilized to address this demand is charge/discharge cycle testing. The goal of the test is to discover how many times a battery can be used by examining it until it deteriorates after repeated charging and discharging cycles.
Under this, the battery is connected to a decade resistor box, the resistance is set to 8 ohms (6.5V and 750mA) to simulate the current draw, and the voltage across the terminal of the battery is measured every 15 minutes with the resistor box connected. The results are collected and a scatter graph can be created to show the relationship of battery discharging. Then high voltage and low voltage disconnected voltages can be determined based on the resulting curve.
Required Equipment
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Equipment Description |
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1 |
Multimeter |
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2 |
Decade resistor box |
Test Procedure
Step 1: Set the decade box as close as possible to 8 ohms
Step 2: Connect the decade resistor box across the battery
terminals.
Step 3: Measure the voltages across the terminals of the battery every
15 minutes when the resistor box is connected.
Record the value in MS Excel.
Step 4: When the battery
terminal voltage drops below 5.8V disconnect the decade box and battery.
The conventional procedure is to charge and discharge at the prescribed charge and discharge rates repeatedly.
Temperature cycle testing, in which the test temperature is raised and dropped by placing the sample in a temperature chamber, is also common. Temperature characteristic testing is carried out to assess how much capacity can be input/output under various temperature circumstances. Discharge temperature characteristic tests and charge temperature characteristic tests are available.
Constant-current load characteristic testing is used to determine how much capacity can be input/output at different current rates. There are discharge load characteristic tests (in which the current rate is varied while the sample is discharging) and charge load characteristic tests (in which the current rate is varied while the sample is charging) (in which the current rate is varied when the sample is charging).
An insulation resistance (IR) test measures the total resistance between any two points separated by electrical insulation. The test, therefore, determines how effective the dielectric (insulation) is in resisting the flow of electrical current. Such tests are useful for checking the quality of insulation, not only when a product is first manufactured but also over time as the product is used.
Performing such tests at regular time intervals can detect impending insulation failures before they occur and prevent user accidents or costly product repairs.
This test usually has four phases: charge, dwell, measure, and discharge. During the charge phase, the voltage is ramped from zero to the selected voltage, which provides stabilization time and limits the inrush current to the DUT. Once the voltage reaches the selected value, the voltage can then be allowed to dwell or hold at this voltage before measurements begin.
Once the resistance has been measured for the selected time, the DUT is discharged back to 0V during the final phase. Insulation resistance testers typically have 4 output connections – ground, shield, (+), and (-) – to cover a wide variety of applications. The output voltage is typically in the range of 50 to 1000 Volts DC. In performing the test, the operator first connects the DUT. The instrument measures and displays the measured resistance. When the voltage is applied, some current immediately starts to flow through the insulation. This current flow has three components – a “dielectric absorption” current, a charging current, and a leakage current.
Required Equipment
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Equipment
Description |
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1 |
Hipot Tester |
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2 |
Electrical Safety Analyzer |
External Short Circuit test simulates an external short circuit.
Test procedure-
The cell or battery to be tested shall be temperature stabilized so that its external case temperature reaches 55 ± 2 °C and then the cell or the battery shall be subjected to a short circuit condition with a total external resistance of fewer than 0.1 ohms at 55 ± 2 °C. This short circuit condition is continued for at least one hour after the cell or battery external case the temperature has returned to 55 ± 2 °C. 38.3.4.5.3 Requirement Cells and batteries meet this requirement if their external temperature does not exceed 170 °C and there is no disassembly, no rupture, and no fire during the test and within six hours after the test.
The low air pressure test r is used for testing the safety capability of the battery in the environment of high altitude and low pressure. The test result: the specimen battery is qualified if non-explosion, no fire, non air leak, nonelectrolyte leakage. The low air pressure test chamber is designed for the test standard of UL, EN, and IEC. The tester can come into a low air pressure state in a short time and control the test period automatically, monitor the change of air pressure in the full process, and finish the test automatically.
Features:
a. The low air pressure tester is used for battery testing the safety
capability of lithium batteries.
b. The tester is simulating an environment of high altitude and
low air pressure.
c. Test result is non-explosion, no fire, non air leaking, and nonelectrolyte leakage for the qualified Battery.
One final test, called the forced discharge test, determines the safety of a battery under certain abusive conditions. This test is very dangerous because, during the test, the battery is very likely to explode. The test must be done under extremely well-controlled conditions in an explosion-proof safety chamber to prevent personal injury. The Test involves connecting a current source in series with the battery. The polarity is in the same direction as normal or short circuit current flow.
The current source asset to a value such that the resultant current flow is greater than the short circuit current flow. This test simulates what may happen if a battery were improperly installed in a circuit where it may not be the only source in the application. Ideally, the battery should withstand the stress, with some degree of margin, when the test currents are similar to actual conditions.
For more information on battery testing, please contact our SigmaTest and Research Centre experts for further assistance.
Contact the Sigma Team For Any Inquiry
Website:- https://www.sigmatest.org
Call on this number +91-9560222333
Mail ID- mail@sigmatest.org
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