How to Protect UAV lithium Battery?

The battery is one of the key factors to ensure that the drone can take off normally. How to increase its service life is a question worth pondering by every drone owner. Drone batteries and mobile phone batteries are lithium batteries. Lithium batteries are the power source of equipment, and their safety performance requirements will be higher. However, there are differences between the two. Drone batteries have a distinctive feature compared to mobile phone batteries-discharge. Drone batteries need to emit different currents in different situations to meet the requirements of DRONE use in different environments. For example, during aerial photography, if a strong wind is encountered, the battery needs to be able to discharge a high current to compensate accordingly to ensure the position of the drone. Because of the different requirements for use, the life of drone batteries is not the same. In order to take care of your UAV lithium batteries. You’d better follow below “Six Don’t”

1. Don’t Over Discharge

The discharge curve of lithium battery shows that at the beginning of discharging, battery voltage drops relatively quickly. However, when the voltage discharges to 3. 9~3. 7V, the voltage drop slows down. Once the voltage drops to 3. 7V, the voltage dropping speed will accelerate, and if people use battery improperly, the lithium battery will over discharge. Over-discharging will damage battery itself and even lead to battery explode or leaks. Some UAV fans will over-discharge every time because they have fewer batteries. So such batteries which are usually being over discharged are very short-lived. So if you are a UAV fan, you can buy enough lithium batteries as backup resources, then you can enjoy much more time in flying UAV. If you are poor in pocket, you can flying shorter distance each time to avoid lithium battery over discharging.

2. Don’t Over Charging

Both over discharging and over discharging will damage lithium batteries in UAV or any other equipment. You can follow below cautions to avoid over charging.

  • Use a dedicated charger. Some mobile phone chargers can be used to charge lithium polymer batterieswhich will not damage the battery.
  • Accurately set the number of battery cells in the battery pack. In the first few minutes of charging, you must carefully observe the display of the charger, which will display the number of batteries in the battery pack. If you are not clear, you should not charge or use a charger you are familiar with.
  • Charge a new lithium battery pack for the first time, check the voltage of each battery cell in the battery pack, and do the same for every 10 charges and discharges in the future. This is absolutely necessary. A battery pack with unbalanced voltage will still burst when the number of batteries is selected to charge correctly. If the voltage difference between the battery cells in the battery pack exceeds 0. 1V, you should charge the voltage of each battery to 4. 2V to make it equal. If the voltage difference of the battery unit exceeds 0. 1V after each discharge, it means that your battery has failed and should be replaced.
  • Do not charge unattended
  • Use a safe location to place rechargeable batteries and chargers.
  • Generally, there is no special instructions from the manufacturer, and the charging current should not exceed 1C. Batteries that now support high-current discharge also support current charging of more than 1C. However, the life of the battery will be greatly shortened. It is more cost-effective to buy 3 batteries to charge alternately than to buy one battery and have to charge quickly.

3. Don’t Store Lithium Battery in Full-energy State

Fully charged batteries cannot be stored at full power for more than 3 days. If they are not released for more than a week, some batteries will be drugged directly. Some batteries may not be drugged for the time being, but after several full-power saves, the battery may be directly reported for scrap. Therefore, the correct way is to recharge after receiving the mission. If there is no mission within 3 days after the battery is used, please charge the monolithic voltage to 3. 80~3. 90V and save it. If the battery does not fly for various reasons after it is fully charged, the battery must be discharged to 3. 80~3. 90V within 3 days after it is fully charged to save it. If the battery is not used within three months, charge and discharge the battery once and continue to save it, which can extend the battery life. The battery should be stored in a cool environment for storage. When storing the battery for a long time, it is best to put it in a sealed bag or in a sealed explosion-proof box. The recommended ambient temperature is 10~25°C, and it is dry and non-corrosive.

4. Do not damage the packaging

The outer packaging of the battery is an important structure to prevent the battery from exploding and leaking liquid from catching fire. Damage to the aluminum-plastic film of the lithium polymer battery will directly cause the battery to catch fire or explode. The battery should be taken lightly, and the cable ties should be tightened when fixing the battery on the aircraft. Because it is possible that when the aircraft is dynamically flying or falling, the battery will be thrown out because the cable tie is not tight, which can easily cause damage to the outer skin of the battery.

5. Don’t Short Circuit

This situation often occurs during the maintenance and transportation of battery welding wires. A short circuit will directly cause the battery to ignite or explode. When it is found that the battery is disconnected after a period of use and needs to be re-soldered, special attention should be paid to the soldering iron not to touch the positive and negative electrodes of the battery at the same time. In addition, in the process of transporting batteries, the best way is to put each battery in a separate self-sealing bag and place it in an explosion-proof box to prevent the positive and negative electrodes of a certain battery from touching other conductive substances at the same time due to bumps and collisions during transportation. Short circuit or broken skin and short circuit.

  1. Don’t Let Battery in ColdTemperature

This principle is ignored by many flying friends. Low-temperature weather often occurs in the north or high-altitude areas. At this time, if the battery is placed outside for a long time, its discharge performance will be greatly reduced. If you still have to fly at room temperature, the flight time will definitely go wrong. . At this time, the alarm voltage should be increased (for example, the monolithic alarm voltage should be adjusted to 3. 8V), because the voltage drop will be very fast in a low temperature environment, and the alarm will land immediately. Then there is the need to keep the battery warm. Before taking off, the battery should be stored in a warm environment, such as in a house, in a car, in an incubator, etc. To quickly install the battery when taking off and perform flight tasks. When flying at low temperatures, try to shorten the time to half of normal temperature to ensure safe flight.

Correct maintenance of the battery, adhere to the “Six DOs”:

1. Do Regular inspection

Regularly check the battery body, handle, wire, and power plug to observe whether the appearance is damaged, deformed, corroded, discolored, and skin-breaking, and whether the plug is too loose from the aircraft.

2. Do Dry-cloth wipe

After each operation, use a dry cloth to wipe the surface of the battery and the power plug to ensure that there are no other corrosive liquids remaining to avoid corroding the battery.

3. Wait for the battery to cool down and charge

After the flight, the battery temperature is higher. You should wait for the flight battery temperature to drop below 40℃ before charging it (the optimal temperature range for flight battery charging is 5℃ to 40℃). After the operation is over, it is recommended to slowly charge the battery for maintenance.

4. Do 1C small current charging

That is, the coefficient of 1 times the capacity is charged. For example, the drone battery capacity is 12000mAh, which means 12A current charging. Do a smaller current (2A) balanced charging once a week, so that the battery consistency can always be maintained in a better state. Of course, with such a small current, the charging time must be longer. When charging, you must ensure that the temperature of the battery itself is room temperature and that it is charged in a cool place. The battery that has just been removed from the aircraft must be recharged after it cools down. Drone low-temperature flight lithium battery must do homework

5. Do Half-electric Storage

That is, the monomer is within 3. 8V-3. 95V. Storage environment: Indoor temperature, it is recommended to put it in an iron box, which is safer. Lithium batteries that have not been used for a long time should be charged and discharged once within 3 months. The smart battery should be charged and discharged once within 2 months.

6. Take it lightly

This can avoid the battery from being deformed or even catching fire due to impact. In addition, be careful to hold the battery cable to hold the battery. These maintenance measures can greatly improve the service life of lithium batteries, thereby reducing operating costs. The implementation of the above general methods of maintenance and maintenance of lithium batteries must be helpful for daily flight work.

With low temperatures in winter, drones are prone to sudden voltage drops and insufficient flight power during flight, which can easily lead to problems such as drone crashes and explosions.

So what problems should we pay attention to when flying drones in winter?

Most of the power for UAV flight is provided by lithium batteries, and the low temperature environment will reduce the performance of lithium batteries. When the battery is exposed to an environment below 15°C, the chemical activity of the battery is significantly reduced, and the increase in its internal resistance leads to a decrease in the discharge capacity, and the voltage drop increases when the battery is discharged. There are two major risks when the voltage drops sharply (a single cell is below 3V):

First, the maximum thrust of the aircraft power system is not enough to maintain flight;

Second, the battery will actively shut down to avoid over-discharge of the battery.

This characteristic is a common problem with lithium batteries, and there is still no perfect solution. Smart devices such as mobile phones and tablets that everyone uses will also shut down in low-temperature environments.

Here I have to mention the flight principle of lithium batteries for drones. For UAV with a larger weight, they need more current to maintain power; the aircraft continues to maneuver, such as when climbing at full throttle, the battery will continue to discharge at high current; in plateau areas, due to thin air and low air pressure, the aircraft needs a higher motor speed to maintain power, and the battery output current will be further increased. The above situation, coupled with the low temperature in winter, further increases the battery voltage drop; in severe cases, it can even cause the battery to shut down due to insufficient voltage, causing the aircraft to lose power and crash.

Under different temperature conditions, the schematic diagram of the discharge voltage curve of the actual operating conditions of the aircraft is shown in the figure. The lower the battery temperature, the lower the battery voltage after take-off. After the battery temperature rises, the voltage slowly returns to normal. If the low battery takes off, the starting voltage of the battery is low at this time, and the temperature of the battery body is low, the voltage will be quickly pulled down, greatly increasing the risk of insufficient voltage. Therefore, we have always emphasized flying at full power.

Battery winter use recommendations:

  1. Before flying, be sure to fully charge the battery to ensure that the battery is in a high voltage state.
  2. Fully preheat the battery to more than 25 degrees to reduce the internal resistance of the battery.
  3. Keep the aircraft hovering for about 1 minute after take-off, so that the battery can use the internal heat to fully preheat itself and reduce the internal resistance of the battery.

Each UAV is of high value. If they fall or explode, they will injure the aircraft and injure people if they are heavy. Flight safety must be a top priority for winter flights.