Lithium polymer batteries have become the most common RC high performance batteries on the market and are often used in RC cars, RC planes and other RC. Lithium polymer batteries are safer and provide more power than other RC batteries.
However, they can become extremely dangerous if not charged, discharged, stored, maintained or disposed of properly, as lithium polymer batteries are flammable. So for how to use lithium polymer batteries safely, there is this lithium polymer safety guide.
Charging Safety Guidelines
All polymer lithium-ion batteries are very afraid of battery overcharge, battery short circuit and other situations. As the battery is recharged and discharged, the internal temperature of the battery continues to rise, the gas produced during activation expands, the internal pressure of the battery increases, and if the pressure reaches a certain level (if the shell is scarred), it ruptures, causing a liquid leak, fire, or even an explosion.
Ordinary polymer lithium-ion batteries use colloidal electrolyte, which will not explode due to large amount of gas from boiling liquid, thus improving safety.
- The charging current and voltage must not exceed the following standards. Exceeding the specified value may damage the charging/discharging characteristics, mechanical performance and safety of the cell, and may also cause heating and leakage.
- The charging current of the single battery during charging must be below 1C5A; the temperature range is 0~45℃; the voltage cannot exceed 4.23V during charging.
- The battery charger must be capable of constant current and constant voltage charging.
- Not allowed to overcharge the lithium polymer battery.
- The environment must be kept dry in the case of charging.
- Do not touch water and other liquids when charging, otherwise it may also lead to leakage, resulting in fire and other situations.
- When charging the polymer lithium battery, choose the original charger, because the original charger charging current is designed for the best current of product charging.
- Lithium polymer batteries should be stopped immediately after being charged to full capacity, otherwise the lithium polymer battery may heat up or overheat and affect the performance of the battery.
- Always follow the manufacturer’s instructions regarding the charging and discharging rates of Li-polymer batteries.
- Do not charge Li-polymer batteries unattended.
Discharging Safety Guidelines
The discharge current must not exceed the following standards. Discharge must be carried out within the scope of this standard:
- The discharge current of a single battery must be less than 2C5A;
- The temperature range during discharge should be controlled from -20 to +60℃.
- The termination voltage when discharging a single cell is not less than 2.75V.
- Not allowed to over-discharge the polymer lithium battery.
- It should be noted that when the battery cell is not used for a long time, it may be in some kind of over-discharge state because of its self-discharge characteristic. Therefore, to prevent the occurrence of over-discharge, the battery cell should be charged regularly and its voltage should be maintained at 3.0V or above.
- In addition, over-discharge can lead to loss of cell performance and battery function.
- The battery can not be over-discharged so that the single cell below 2.5V.
- In the specific use of the battery should require the addition of qualified protection circuit board.
Maintanence & Storage Safety Guidelines
Some general principles of storage:
- Not allowed to store in places with strong static electricity and strong magnetic field, otherwise it is easy to destroy the battery safety protection device and bring unsafe hidden danger.
- Storage voltage and capacity: voltage is 3.7V~3.9V ; The range of capacity of battery is: between 30%-70%.
- Always store the battery in a fireproof container.
If the lithium battery is not used for a short period of time (such as within 5 months), the battery should be stored in a dry, non-corrosive gas, temperature and humidity between -20°C~35°C. Above or below this temperature and humidity will cause the metal parts of the battery to rust or the battery to leak.
1. Lithium batteries are not used for a long time (such as more than 6 months) should be stored at 50% to 70% of the battery capacity, and removed from the instrument and stored in a dry and cool environment. In addition, the battery should be charged once every 3 months to avoid storing for too long.
Battery self-discharge leads to low power, resulting in irreversible capacity loss.
2. The self-discharge of lithium battery is affected by the ambient temperature and humidity, high temperature and humidity will accelerate the self-discharge of the battery. Therefore, it is recommended that the battery be stored in a dry environment at 10°C~25°C.
Requirements of Storage Warehouse:
1. The warehouse can control the temperature and humidity. If there is an air conditioner or dehumidification equipment, it can avoid the battery for a long time in high humidity environment.
2. The warehouse should have automatic fire extinguishing system, emergency sprinkler system, dry powder fire extinguishers and fire sand.
3. Cannot be placed in the same warehouse with flammable materials (such as packaging materials cartons, cartons, etc.). It is recommended to use an independent warehouse.
4. Second level fire doors.
5. Place the lithium battery according to the instruction mark and stacking requirements on the package, and forbid to stack the layer over the limit.
Long Time Storage Treatment:
It is usually not recommended to store lithium batteries for more than two years, because the longer the storage time, the more serious the loss of battery capacity.
According to the “long-term storage” method, batteries can usually be stored for two or three years. During this period, the battery usually does not have other bad performance except for capacity decay, but the charging and discharging time (using time) will be shortened when assembled into the equipment, which is usually called “the battery runs out of power soon after charging”. When the battery is used for less than the customer’s specified time, it will be treated as defective or scrapped by the customer or user.
Requirements for maintenance and safety protection personnel:
- Trained in lithium battery knowledge, lithium battery maintenance knowledge and safety protection knowledge.
- Received fire safety training.
Transpotation Safety Guidelines
- Batteries should be transported at 10% to 50% of capacity.
- During the transportation of lithium battery, attention should be paid to moisture and humidity prevention, to prevent extrusion, collision, etc. to avoid damage to the battery.
- Lithium batteries loaded in containers shall be reinforced, and the reinforcement method and strength shall meet the requirements of the importing country.
- Lithium batteries should be loaded on pallets to avoid strong vibrations during handling and protected by corner guards on each vertical and horizontal side of the pallets
- The equipment should be secured to prevent movement within the package and packaged in such a way as to prevent accidental start-up in transit
- The outer packaging should be waterproof, or be waterproof through the use of a liner (such as a plastic bag), unless the construction characteristics of the device itself already have waterproof characteristics.
Disposal Safety Guidelines
- In order to prevent the battery from possible leakage, heat and explosion, please note the following precautions.
- It is forbidden to disassemble the battery cells under any circumstances.
- It is forbidden to immerse the battery in water or seawater, and it must not be exposed to moisture.
- It is forbidden to use or place the battery next to a heat source, such as fire, heater, etc.
- It is forbidden to heat or throw the battery into the fire.
- It is forbidden to solder the battery directly.
- It is forbidden to charge by fire or in a very hot environment.
- It is forbidden to put the battery into microwave oven or high pressure container.
- It is forbidden to use or place the battery under high temperature (such as strong sunlight or in a very hot car), otherwise it will cause overheating, fire or function deterioration and life reduction.
- Polymer lithium-ion battery theoretically does not have flowing electrolyte, but in case of electrolyte leakage and contact with skin, eyes or other parts of the body, you should immediately flush the electrolyte with water and seek medical attention.
- It is forbidden to use damaged battery cells (damaged plastic sealing of battery cells, broken shell, smell of electrolyte gas, electrolyte leakage, etc.).
If there is electrolyte leakage or smell of electrolyte, the battery should be kept away from the fire source to avoid fire or explosion.
Long-term storage of lithium batteries may occur leakage, rust, bulging phenomenon; such as improper operation may occur fever, combustion or explosion, etc., the relevant treatment methods are as follows：
Dispose of Rust:
Usually, for cylindrical Li-ion batteries (Li-polymer batteries do not have this phenomenon), the initial, slight rust will not affect the performance of the Li-ion battery and can be used normally. If the rust is serious (such as the cap area), it will affect the battery sealing performance and leakage, and must be scrapped.
Dispose of Leakage or Bulging:
Leakage is the leakage of electrolyte out of the battery, which usually has a pungent smell. Electrolyte is very corrosive and will cause damage to the battery protection board components. If it is a lithium polymer battery will occur bulging accounts, leaking and bulging batteries must be picked out and scrapped for disposal.
Under normal environmental conditions of temperature and humidity, the battery will not produce mold or discoloration. However, if leakage occurs, it will produce such undesirable phenomenon.
Dispose of Heat Generation:
Battery in charging and discharging (using state) will heat up, but the temperature is usually below 60 degrees. When the battery in the internal or external short circuit state, the temperature will reach hundreds or hundreds of degrees, then the battery must be isolated and placed in the sand. Note that you can not directly touch the battery with your hands, otherwise it will be scalded. When the battery temperature drops to normal temperature, do scrap processing.
Disopse of Combustion or Explosion:
If there is a burning or explosion phenomenon, it is very dangerous, and personnel must stay away.
Battery combustion will not produce an open flame, usually due to high temperature ignited next to flammable or packaging box. Under the premise of good protective measures, such as single or very few batteries burning or exploding fire extinguishing method: use sand directly cover the burning or exploding batteries. If a large area is burned, use dry powder extinguisher. Do not use water to extinguish the fire, because water will cause short circuit of the battery.