18650 Battery Repair Too

1. Analysis of common problems and causes of damage to the 18650 battery

1.1 Low battery capacity: causes and effects

Low 18650 battery capacity is one of the most common problems encountered by users, mainly due to overcharging and discharging, use in high-temperature environments, natural aging, etc. According to the test data of the Hong Kong Consumer Council, the capacity of the 18650 battery can drop to less than 70% of its original capacity after frequent charging and discharging (more than 500 cycles). Additionally, electrolyte breakdown and changes in electrode material structure can also lead to reduced capacity, affecting the durability of the equipment. If the battery life is significantly reduced after charging, it is better to give preference to testing the capacity.

1.2 Increased Internal Resistance of Batteries: Affects Performance and Safety

The increased internal resistance can lead to increased battery heat generation and reduced output power, which can lead to potential safety hazards in severe cases. Common causes include oxidation of the electrodes, drying of the electrolyte (especially in high-temperature environments), or process defects during production. In real measurements, when the internal resistance exceeds 80mΩ, the efficiency of the battery is significantly reduced. Such problems should be diagnosed with specialized equipment, such as internal resistance testers, and components should be replenished or replaced as needed.

1.3 Battery Short Circuit and Over-Discharging: Potential Hazards

A short circuit can be caused by external extrusion or damage to the internal separator, which can cause high temperatures and fires in an instant. Over-discharge (voltage less than 2.5V) causes irreversible damage to the electrodes. According to a 2022 report by the Hong Kong Fire Department, about 35% of lithium battery-related fires are related to over-discharge/short circuit. Before repairing, be sure to check the battery for any swelling or leakage, and if so, dispose of it directly.

2. Introduction to Common 18650 Battery Repair Tools

2.1 Basic Tools: Multimeter, Soldering Gun, Disassembly Tool

The multimeter is a core tool for detecting voltage/resistance, and it is recommended to choose an auto-range model (with an accuracy of at least ±0.5%). A special pry bar is required for disassembly (to avoid short circuits in metal tools), a 60W temperature-adjustable type is recommended for soldering guns, and a welding wire containing silver is used to reduce contact resistance. The basic tool set costs around HK$300-500, making it suitable for beginners.

2.2 Advanced Tools: Professional Chargers, Battery Activators, and Internal Resistance Tester

Commercial chargers such as the SKYRC MC3000 can perform charge-discharge cycle repairs, and activators can pulse vulcanized batteries. High-precision resistance testers, such as the YR1035+, can detect changes in the 0.01 mΩ level, which is essential for determining the state of the electrolyte. Such a tool will invest around HK$2,000 to HK$5,000, but it can significantly improve the success rate of repairs.

2.3 Safety equipment: anti-static gloves, goggles

Explosion-proof goggles (ANSI Z87.1 standard) and insulating gloves (withstand voltage of 500V or higher) are required. The Hong Kong Occupational Safety and Health Bureau reminds you to wear an N95 mask in a well-ventilated area when handling electrolytes to avoid inhaling volatile gases. The package of safety equipment is around HK$200, which is the lowest cost protection for accident prevention.

3. Specific Steps and Tips for 18650 Battery Repair

3.1 Battery Detection: Use a multimeter and an internal resistance tester

Test the open circuit voltage beforehand: A normal battery should be 3.6-4.2V. If it is less than 2.5V, you need to handle it with care. The internal resistance (normal value 20 to 50 mΩ) was then measured in a 4-wire formula and the self-discharge rate (24-hour voltage drop >0.1 V is abnormal) was recorded. Example table:

 

 

item	Normal range	Outliers
voltage	3.6-4.2V	4.3V
Internal resistance	20-50mΩ	>80mΩ

3.2 Disassembling the Battery: Safety Precautions and Disassembly Methods

Use a plastic saw rod to slowly separate it along the edge of the plus battery (to avoid damaging the separator). If you fix it with a strong glue, you can soften it with isopropyl alcohol. Important Note: Disassembly of the extended battery should be done in an explosion-proof box and away from open flames. After successful disassembly, immediately cover the electrodes with insulating tape to prevent short circuits.

3.3 Cleaning the Battery and Removing Rust

Use a cotton pad of anhydrous alcohol to clean the erosion of the electrodes, and the stubborn oxide layer can be lightly sanded with 600 grit sandpaper. Note:

 

• It is strictly forbidden to wash with water and use corrosive solvents
• It must be cleaned before assembly and then dried thoroughly
• If crystals (white powder) of the electrolyte are found, the separator must be replaced

3.4 Starting and Charging the Battery

For deep discharge batteries, first charge to 3.0V with a small current of 0.1C, and then charge with standard current (0.5C). The activator can apply 3-5 charge-discharge cycles (0.2C discharge/0.5C charge), and can restore about 60% of the over-discharged battery to more than 80% capacity.電池 セパレーター 電解液

3.5 Assembling and Testing the Battery

During assembly, ensure that the electrodes are aligned and that the new separator completely covers the electrodes. After spot welding, the resistance of each contact is measured (5 mΩ)

4. Repair plan under various damage situations

4.1 Capacity Attenuation: Charging and Pairing Activation

For batteries that have been cycled more than 300 times, we recommend the following:

 

• After performing a deep discharge (up to 2.8V), it will charge slowly for 12 hours.
• When used in pairing, the capacity difference must be controlled within ±5%
• If the capacity is less than 60% of the nominal value, it is recommended to dispose of it

4.2 Increased Internal Resistance: Electrolyte Replenishment (Caution)

Removable battery only:

 

1. Inject a special lithium battery electrolyte (about 0.5 ml per cell)
2. Let stand for 24 hours to make the infiltration separator
3. Internal resistance flux test (ideal drop of 10-15mΩ)

Warning: Incorrect actions can lead to thermal runaway.

4.3 Short Circuit: Find and correct the short circuit point

Use the thermal imager to identify hot spots, common repair methods.セル組み立て機械

 

• Replacement: Breakage separator
• Electrode burr removal (under microscope)
• Redo the insulation (polyimide tape)

4.4 Over-Discharging: Try to Activate Charging

For batteries with a voltage of 2.0-2.5V:18650 バッテリー 修理

 

1. Connection Resistor (100Ω) Current Limit 30 minutes Charge
2. Switch to 0.05C current and charge 3.0V
3. Monitor temperature throughout the process (below 40°C)

5. Suggestions for daily maintenance and use of the 18650 battery

5.1 Correct Charging Method

Proposal:

 

• Genuine charger (cut-off voltage accuracy±0.05V)
• Avoid long-term storage on a full charge (40-60% battery is best)
• The fast charging temperature should be controlled in the range of 25-35°C

5.2 Avoid Overcharging and Over-Discharging

Important rules:

 

• Discharge cut-off voltage of 2.8V or higher (3.0V is safer)
• Use a timed socket when charging (within 8 hours)
• Multiple battery packs must be equipped with a balanced charging module

5.3 Storage Precautions

According to the Hong Kong Climate Advisory:

 

• Moisture-proof box (humidity)
• Stay away from windows and avoid direct sunlight
• Charging and discharging maintenance every 3 months

5.4 Periodic Inspection and Maintenance

Monthly regular check-ups:

 

1. Measures open circuit voltage (0.2V> abnormal fluctuations should be exercised)
2. Observe whether the shell expands and deforms
3. Cleaning of electrode contacts (DeoxIT spray)

By using the above methods, you can extend the life of your 18650 battery by more than 5 years while also reducing the need for 18650 battery repairs. If you need a professional cell assembly machine or to ensure the safety of your materials, we recommend purchasing from authorized suppliers in Japan or Germany.