22 Years' Battery Customization
Jun 20, 2020 Pageview：713
Safety concerns of lipo batteries have raised eyebrows. All energy devices are at risk of explosion and even hurt people. Batteries manufacturers are obligated to meet the safety performance of cells. Lithium batteries are safe to use but with many users, failures can happen. According to Sony maker, tiny metal particles can come in contact with parts of the cell hence result in a short circuit. Let us learn if lithium batteries are dangerous, the causes of fire, and how to stop.
What causes a lipo battery to catch fire?
Overcharging
Lipo cells are the most efficient power in the market with the highest specific energy. For this reason, you will get more capacity and power from a small and light battery. Lipo cells are charged to 4.20V then discharged to 3.0V per cell. Henceforth, the higher or lower voltage will be damaged and become unstable which is dangerous. For instance, if the voltage of one cell exceeds 4.20V, it becomes unstable. The cell will overheat, swell then rupture and spill electrolytes that cause a fire. In addition to that, lipo batteries are different from other cells thus you should never use NiMH/ NiCd charger.
Metallic Particles
On rare occasion, there are microscopic particles metal particles can come in contact with battery's part hence cause a short circuit in the cell. Manufacturers are trying to reduce the metallic particles. Additionally, Semiconductor Company has used billions of money to lower particles which minimize yield in wafers. Regardless of high cleanliness, particles are still present in semiconductor wafers.
Incorrect Uses
Improper uses of cells include charging below freezing point, elevated heat, and excessive vibration. Lipo is not fully discharged and should always be stored with charge. This is because of copper forms in the cell which results to elevate self-discharge. The cells become unstable and cause excess heat.
Uneven Separators
Batteries with thin separators are riskier to impurities compared to older designs. Heat is a great enemy to cells. The presence of uneven separators triggers a battery failure. Dry areas caused by poor conductivity increases resistance that weakens separator and generates heat spots.
Wrong Charger
Lipo batteries are different from other batteries. Therefore, they have a charger. When you use a different one, it can result to fire. Also, use the correct balancing charger for lipo. It will help to keep the cell on the same voltage.
Are lipo batteries that dangerous?
Even though they are the safest cells, Lipo batteries can sometimes become highly dangerous. Many people do not know that the cells are unpredictable. They can be dangerous if users have not followed guidelines on how to deal with them. Here are measures to prevent any risks.
Safety Measures
Do not leave a charging cell unattended
Multifunction charger should be strictly for lipo mode
Put battery and charger on a surface that is non-flammable such as ceramic tile, make sure there are no flammable objects around while charging.
Ensure the total voltage of the pack does not exceed that of cells inside the pack (5 by 4.20V= 21.00).
You can place the cell in a special lipo bag or a fireproof container when charging.
Stop the charging process if the cell swells or get warm, disconnect, and place the battery in proper space and observer for hours.
Do not change or recover damaged or swollen battery pack which is below 3.0V.
Use charge leads and insulated connectors.
Heat is a battery’s enemy, never charge a cell immediately after use, let it cool down completely.
Charge the battery at 1C or less.
Do not overcharge, always check voltages regularly.
Do not leave the cell in a hot car or sun.
Never buy a used lipo cell, you are not aware of what the owner did and could be bad.
You must have a fire extinguisher nearby during charging and discharging a battery. Keep the storage place free from flammable materials such as carpet, wood tables, and gasoline cans.
Do not leave the battery to stay at full charge for 2 to 3 days.
Charger Parameters
Charge current should never go beyond 1C, 1500mAh cell: 1.5A.
The number of cells should be or nominal voltage should be similar to lipo. For example, 3s is charged with 3s or 11.1 settings.
Balance has to be used to balance the voltage of the battery during charge.
How do you stop a lipo battery fire?
A small lipo battery is handled like other combustible fire. You can use foam extinguisher, ABC dry chemical, CO2, sodium carbonate, copper powder, or powdered graphite. If the fire starts in an airplane cabin, flight attendants are instructed to use water or soda pop. Water-based products are readily available. Also, they are appropriate because lipo has little lithium which reacts with water. Moreover, water cools nearby areas as well as prevents the spread of fire. Factories and research laboratories use water to stop lipo battery fire.
It is not possible for the crew to access cargo places of aircraft during flight, planes need to depend on the fire suppression system to ensure safety. The most common fire suppressant is called halon. Nonetheless, the agent is not enough to extinguish a fire in the cargo bay. According to the FAA test, halon cannot extinguish a fire which combines with cosmetics and aerosol. However, it will stop the spread of flammable materials like clothing and cardboard.
Improved methods have been developed to extinguish fires. AVD fire extinguishers for small fire are available in 400ml aerosol. AVD canisters for large fire are available in 50 liters. There is also a module system to be carried on a pickup truck. Besides that, when a battery bulges, hisses or overheats, move the device from flammable materials and puts it on a non-flammable surface.
Final Thoughts
Today, the safety of the new cell is done by releasing a million samples to be observed. The bell is used for critical missions and if the failure does not occur in a year that approves safety. A field testing procedure is also done on pharmaceutical products. Most lithium cell manufacturers x-ray cells and it has become an automated quality control. The software assesses problems like crushed rolls and bent tabs. For this reason, lipo batteries are one of the safe cells today. However, careful manufacturing procedures are only given with recognized brands. Most importantly, the correct use of a cell will prevent anomalies.
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