Polymer Battery Charger Testing: Precautions and Operational Procedures

--A&S POWER Team

1. Introduction

Polymer batteries, also known as lithium - polymer batteries, have gained widespread popularity in various applications due to their high 

energy density, lightweight, and flexibility. However, the safe and efficient operation of these batteries depends significantly on the quality 

and proper functioning of their chargers. Polymer battery charger testing is a multi - faceted process that involves ensuring compliance with 

safety standards, evaluating charging performance, and verifying the reliability of the charger under different conditions.

2. Safety Precautions Before Testing

2.1 Personal Protective Equipment (PPE)

Gloves: Wear heat - resistant and insulating gloves. Polymer battery chargers can generate high temperatures during operation, and there 

is also a risk of electric shock. Gloves made of materials such as neoprene or leather - based insulated gloves can protect hands from burns 

and electrical hazards.

Safety Glasses: Protect your eyes from potential splashes of electrolyte (in case of battery leakage during testing) or any debris that may 

be ejected due to a malfunctioning charger or battery.

Lab Coat: A lab coat provides an additional layer of protection against chemical spills and electrical arcing. It should be made of flame - 

retardant materials to minimize the risk of injury in case of a fire.

2.2 Testing Environment

Ventilation: Ensure that the testing area is well - ventilated. Polymer batteries can release harmful gases such as lithium fluoride, carbon 

monoxide, and hydrogen during overcharging, short - circuiting, or other abnormal conditions. Adequate ventilation helps to dissipate 

these gases and prevent inhalation.

Fire - Resistant Surfaces: Conduct tests on fire - resistant workbenches or tables. Have a fire extinguisher rated for electrical and chemical 

fires (such as a Class C or Class ABC fire extinguisher) readily available in the testing area.

Isolation: Keep the testing area isolated from flammable materials, other electrical equipment, and unauthorized personnel. This reduces 

the risk of collateral damage in case of an accident.

2.3 Equipment Inspection

Charger Inspection: Before starting the test, carefully inspect the polymer battery charger for any visible signs of damage, such as cracked 

casings, frayed wires, or loose connections. A damaged charger can pose a serious safety risk during testing.

Battery Inspection: Check the polymer battery for any signs of swelling, leakage, or physical damage. A damaged battery may not perform 

as expected during charging and can be a safety hazard.

Testing Instruments: Ensure that all testing instruments, such as multimeters, oscilloscopes, and power analyzers, are in good working 

condition and properly calibrated. Incorrectly calibrated instruments can lead to inaccurate test results.

3. Charger Functionality Testing

3.1 Input Voltage and Current Testing

Voltage Range: Connect the charger to a variable power supply and vary the input voltage within the specified range (e.g., for a common 

USB - powered charger, the input voltage range may be 100 - 240V AC). Measure the input voltage using a multimeter and ensure that the 

charger can operate stably within this range.

Current Consumption: Use a power analyzer to measure the input current of the charger at different input voltages and load conditions 

(i.e., with and without a connected battery). The charger should not draw excessive current, as this may indicate inefficiencies or potential 

electrical problems.

3.2 Output Voltage and Current Testing

No - Load Output Voltage: With no battery connected to the charger, measure the output voltage using a multimeter. The output voltage 

should be within the specified tolerance of the charger's rated output voltage (e.g., for a 4.2V lithium - polymer battery charger, the no - 

load output voltage may be 4.2V ± 0.05V).

Loaded Output Voltage and Current: Connect a suitable load (a variable resistor or a battery simulator) to the charger to simulate 

different charging conditions. Measure the output voltage and current simultaneously using a multimeter and an ammeter. As the load 

resistance changes, the charger should be able to adjust the output voltage and current to maintain a stable charging process. For 

example, during the constant - current charging phase of a lithium - polymer battery, the charger should be able to deliver a consistent 

current until the battery voltage reaches a certain level.

3.3 Charging Phases Testing

Constant - Current Phase: Monitor the charger's operation during the constant - current charging phase. The charger should be able to 

deliver the rated charging current (e.g., 1A for a 1000mAh battery) until the battery voltage approaches the constant - voltage threshold. 

Measure the current and voltage at regular intervals to ensure that the charger maintains the correct charging parameters.

Constant - Voltage Phase: Once the battery voltage reaches the constant - voltage level (e.g., 4.2V for a single - cell lithium - polymer 

battery), the charger should automatically switch to the constant - voltage charging phase. During this phase, the charger should gradually 

reduce the charging current while maintaining the output voltage at the constant - voltage level. Monitor the transition between the two 

phases and ensure that there are no sudden spikes or drops in voltage and current.

Termination Conditions: Check the charger's ability to detect the end of the charging process. Most polymer battery chargers terminate 

charging when the charging current drops below a certain percentage (e.g., 10% of the rated charging current) of the initial constant - 

current value. Verify that the charger stops charging at the appropriate time to prevent overcharging.

4. Safety - Related Testing

4.1 Over - Voltage Protection (OVP)

Testing Procedure: Gradually increase the output voltage of the charger using a variable load or a battery simulator until the over - voltage 

protection mechanism activates. Measure the voltage at which the OVP kicks in and ensure that it is within the specified limits. Once the 

OVP is triggered, the charger should immediately stop charging and may enter a safety mode, such as shutting down the output or reducing 

the voltage to a safe level.

Recovery: Check the charger's ability to recover from the OVP condition. After the over - voltage situation is resolved (e.g., by reducing the 

load or disconnecting the abnormal battery), the charger should be able to resume normal operation without any permanent damage.

4.2 Over - Current Protection (OCP)

Testing Procedure: Increase the load current on the charger by reducing the load resistance or simulating a short - circuit condition (using a 

current - limiting resistor to prevent excessive current flow that could damage the charger or battery). Monitor the charger's response as the 

current approaches and exceeds the rated over - current threshold. The charger should detect the over - current situation and take appropriate 

action, such as shutting off the output or limiting the current to a safe value.

Response Time: Measure the time it takes for the OCP mechanism to activate. A fast - acting OCP is crucial to prevent damage to the battery 

and charger in case of a short - circuit or excessive current draw.

4.3 Short - Circuit Protection

Testing Procedure: Connect a short - circuit between the charger's output terminals using a jumper wire (with appropriate current - limiting 

measures in place). The charger should detect the short - circuit condition and immediately stop delivering power. After removing the short - 

circuit, the charger should be able to return to normal operation without any damage.

Repeatability: Perform the short - circuit test multiple times to ensure that the charger's short - circuit protection mechanism is reliable and 

consistent in its operation.

4.4 Thermal Protection

Testing Procedure: Operate the charger under heavy - load conditions (e.g., charging a high - capacity battery at the maximum rated current) 

for an extended period to increase the internal temperature of the charger. Use a thermal camera or temperature sensors to monitor the 

temperature of critical components, such as the power transistors, transformers, and printed circuit board. When the temperature reaches 

the thermal protection threshold, the charger should either reduce the charging current or shut down to prevent overheating.

Cooling and Recovery: After the charger's temperature drops below the thermal protection threshold, check if it can resume normal operation 

without any degradation in performance.

5. Environmental Testing

5.1 Temperature and Humidity Testing

High - Temperature Testing: Place the charger in a temperature - controlled chamber and raise the temperature to the specified high - 

temperature limit (e.g., 60°C or 70°C). Operate the charger at this temperature for a certain period (e.g., 24 hours) while charging a battery. 

Monitor the charger's performance during this time, including its ability to maintain the correct charging voltage and current, and check for 

any signs of damage or malfunction.

Low - Temperature Testing: Lower the temperature in the chamber to the specified low - temperature limit (e.g., - 20°C). Similar to the high - 

temperature test, operate the charger at this low temperature and observe its performance. Some chargers may have reduced efficiency or 

may not function properly at very low temperatures, and this test helps to identify such issues.

Humidity Testing: Set the chamber to a high - humidity environment (e.g., 90% relative humidity) and conduct tests on the charger. High 

humidity can cause corrosion of electrical components, so it is important to ensure that the charger can withstand such conditions without 

developing any electrical or mechanical problems.

5.2 Vibration and Shock Testing

Vibration Testing: Mount the charger on a vibration table and subject it to different vibration frequencies and amplitudes according to the 

relevant standards (e.g., IEC 60068 - 2 - 6). During the vibration test, operate the charger and monitor its performance. Check for any loose 

components, cracked casings, or electrical failures that may occur due to the vibration.

Shock Testing: Use a shock tester to apply sudden shock forces to the charger. The shock should simulate real - world situations such as 

drops or impacts. After the shock test, inspect the charger for any physical damage and test its functionality to ensure that it can still operate 

normally.

6. Testing Documentation

Test Plan: Develop a detailed test plan before starting the testing process. The test plan should include the test objectives, test methods, 

test conditions, and the expected results for each test item.

Test Records: Keep accurate records of all test results, including the input and output voltage and current measurements, the activation 

points of safety protection mechanisms, and any observations during the testing process. Use a standardized form or a test management 

software to record the data.

Test Report: After completing all the tests, prepare a comprehensive test report. The report should summarize the test results, compare 

them with the specified requirements and standards, and conclude whether the polymer battery charger meets the acceptance criteria. 

Include any recommendations for improvement if the charger fails to meet certain requirements.

7. Conclusion

Testing polymer battery chargers is a complex and essential process to ensure the safety, reliability, and performance of these chargers. 

By following the safety precautions, conducting thorough functionality, safety, and environmental tests, and maintaining proper documentation, 

manufacturers and testers can ensure that polymer battery chargers are of high quality and suitable for use with polymer batteries in a wide 

range of applications. Regular testing and quality control of chargers not only protect the end - users from potential safety hazards but also 

enhance the reputation and competitiveness of the products in the market.

Stay tuned for more updates on the latest advancements in battery technology. For further details about the lipo battery and other innovative 

products, visit Shenzhen A&S Power Technology Co., Ltd’s official website https://www.szaspower.com/.