18650 battery 3.7v 3500mah

　　Detailed explanation of fully online 18650 battery 3.7v 3500mahdischarge safety and energy-saving technology

　　The quality of communication backup batteries is an important guarantee for the uninterrupted power supply of the communication network. It is the power supply guarantee for the entire communication power equipment and the last line of defense to ensure the normal operation of the communication network. According to the 18650 battery 3.7v 3500mahcharacteristics and maintenance requirements, 18650 battery 3.7v 3500mahdischarge capacity testing is essential. This article discusses the pros and cons of the two current 18650 battery 3.7v 3500mahdischarge capacity testing technologies, provides an innovative full-online 18650 battery 3.7v 3500mahdischarge safety and energy-saving technology, and conducts useful exploration to solve the safety hazards of 18650 battery 3.7v 3500mahdischarge testing in the industry for decades.

　　1 Analysis of current 18650 battery 3.7v 3500mahdischarge technology

　　1.1 Technical analysis of offline discharge method

　　(1) After one group of batteries is disconnected from the system, once the mains power is interrupted, the system backup 18650 battery 3.7v 3500mahpower supply time is significantly shortened. Moreover, it is not yet clear whether there are quality problems with the other group of online batteries. This discharge method has a high risk of accidents. If you want to discharge in this way, it is recommended to start the engine set in advance and ensure that the generator set, switching power supply and other equipment can operate normally to ensure safety;

　　(2) There is a large voltage difference between the 18650 battery 3.7v 3500mahpack after offline discharge and the online 18650 battery 3.7v 3500mahpack. Improper operation will cause the switching power supply and the online 18650 battery 3.7v 3500mahpack to charge the 18650 battery 3.7v 3500mahpack after offline discharge with high current, resulting in huge sparks, which is prone to happen. safety incident. To discharge in this way, a whole set of smart chargers needs to be equipped. The offline 18650 battery 3.7v 3500mahpack should be charged and restored first and then connected back to the system in parallel to solve the spark problem. This will keep the system in a single-set power supply state for a longer period of time and reduce the risk of accidents. high. In addition, the connection is restored by adjusting the rectifier output to be equal to the voltage of the discharged 18650 battery 3.7v 3500mahpack. The above operations must be performed with caution;

　　(3) When operating in this discharge mode, it is necessary to disconnect both the positive electrode and the negative electrode of the 18650 battery 3.7v 3500mahpack. Particular care must be taken when disconnecting the negative electrode of the 18650 battery 3.7v 3500mahpack. Improper operation may cause a short circuit of the negative electrode, which will interrupt the system power supply and lead to communication accidents. happened;

　　(4) This method consumes the 18650 battery 3.7v 3500mahin the form of heat through dummy loads, wastes electric energy, affects the operating environment of the equipment in the computer room, and requires maintenance personnel to guard it at all times to prevent accidents caused by high temperatures.

　　1.2 Technical analysis of online evaluation discharge method

　　(1) Adjust the rectifier output voltage to the protective low voltage value (such as 46V), so that all backup 18650 battery 3.7v 3500mahpacks can directly discharge the actual load to the rectifier output voltage protection setting value. Since most of the 18650 battery 3.7v 3500mahconfigurations of the current network system equipment have a backup power supply time of 1 to 4 hours and a large discharge current, the voltage drop from the 18650 battery 3.7v 3500mahpack to the equipment power supply circuit and the low-voltage operating threshold of the equipment should be considered, as well as to ensure the safety of the system power supply, and adjust the online evaluation discharge The output voltage of the rectifier is not allowed to be too low (such as 46V), the discharge depth is limited, it is difficult to grasp the discharge time of the actual load, it is difficult to accurately evaluate the 18650 battery 3.7v 3500mahcapacity, and there are uncertain factors in the 18650 battery 3.7v 3500mahperformance test, thus it is very important to maintain the activity of the 18650 battery 3.7v 3500mahpack. The discharge test purpose is difficult to achieve the expected maintenance results;

　　(2) If both sets of batteries have quality problems such as loss of capacity, insufficient capacity, or backwardness, it will be difficult for maintenance personnel to detect them in time when they are discharged to the rectifier output protection value. At this time, there may be little backup 18650 battery 3.7v 3500mahcapacity left, and there is a high risk. risk. In this case, this discharge method is less safe than the offline discharge method;

　　(3) Due to the limited discharge depth, the purpose of the discharge test of maintaining the activity of the 18650 battery 3.7v 3500mahpack cannot be achieved. More importantly, in the practice of full-capacity discharge, we often find that some 18650 battery 3.7v 3500mahpacks perform normally in the early stage of discharge, but fail to Later, some backward batteries began to be gradually exposed. This part lags behind the cell and the discharge pattern is not deep enough to be detected. So we call this discharge method an online evaluation method. It can only roughly evaluate the performance of the 18650 battery 3.7v 3500mahpack, or detect how long the 18650 battery 3.7v 3500mahpack can be discharged to this protection voltage, but cannot further check how long it can be discharged beyond this time;

　　(4) The 18650 battery 3.7v 3500mahdischarge current is unbalanced between groups. Each 18650 battery 3.7v 3500mahpack will naturally share the system's load current for discharge according to its own conditions. A backward 18650 battery 3.7v 3500mahpack has a large internal resistance and a small shared current, while a healthy 18650 battery 3.7v 3500mahpack has a low internal resistance and a large shared current, causing some backward batteries to have insufficient discharge current. A phenomenon that is too large to be exposed cannot achieve our purpose of discharge performance quality testing.

　　To sum up, under the requirement that batteries in the central computer room must be regularly tested for capacity, there are currently two capacity testing methods, each with its own characteristics and disadvantages. Although the offline discharge method can achieve the purpose of 18650 battery 3.7v 3500mahcapacity testing, the workload is too large. , the system security is low, and although the workload of the online evaluation discharge method is relatively small, the system security is low, the purpose of 18650 battery 3.7v 3500mahcapacity testing cannot be achieved, and the potential safety hazards are large. Therefore, the current 18650 battery 3.7v 3500mahcapacity testing method must be reformed, and a new and scientific capacity testing technology - full online discharge technology will be introduced to enable the 18650 battery 3.7v 3500mahdischarge capacity test to achieve the expected maintenance quality detection results, and the 18650 battery 3.7v 3500mahdischarge maintenance operation is simple and safe , which improves the efficiency of maintenance work and is easily implemented effectively.

　　2 Full online discharge technology analysis

　　Full online discharge technology means that the 18650 battery 3.7v 3500mahpack under test increases the online power supply voltage through the 18650 battery 3.7v 3500mahpack full online discharge test equipment in series, and automatically stabilizes the current or controls the output with constant power, so that the 18650 battery 3.7v 3500mahpack under test supplies power to the online load equipment, realizing the 18650 battery 3.7v 3500mahunder test Set up constant current discharge test or constant power discharge test to achieve safe and energy-saving maintenance effects. The system technical schematic diagram is shown in Figure 1.

　　[page]The principle of discharge technology is shown in Figure 2. Analysis of the full online discharge principle of the tested 18650 battery 3.7v 3500mahpack: As shown in Figure 2, the 18650 battery 3.7v 3500mahpack full online discharge equipment is connected in series with the positive electrode of the tested 18650 battery 3.7v 3500mahpack, so that the voltage of the branch where the tested 18650 battery 3.7v 3500mahpack is located is slightly higher than the rectifier output or another The voltage of the 18650 battery 3.7v 3500mahpack, so that the 18650 battery 3.7v 3500mahpack can discharge the actual load. During the discharge process, the measured 18650 battery 3.7v 3500mahpack voltage changes (gradually decreases) with the change (prolongation) of the discharge time, and is automatically carried out by the fully online discharge equipment. Voltage compensation adjustment ensures that the 18650 battery 3.7v 3500mahpack under test always maintains a constant current or constant power for discharge. When the 18650 battery 3.7v 3500mahpack discharge end voltage, capacity, time and cell voltage reach the discharge threshold value set by us, the discharge test is completed. . Realize the online discharge test purpose and expected maintenance effect of the 18650 battery 3.7v 3500mahpack. The working principle of full online discharge is shown in Figure 3.

　　2.1 After the online discharge is completed, the online charging is automatically completed and the equipotential connection is restored.

　　After the discharge test of the 18650 battery 3.7v 3500mahpack under test is completed, the fully online discharge equipment of the 18650 battery 3.7v 3500mahpack automatically enters the charging program, guides the rectified output of the online switching power supply, and automatically charges the discharged 18650 battery 3.7v 3500mahpack under test through the charging and equipotential control protection circuit of the fully online discharge test equipment. Carry out current-limiting charging and automatically complete the online equipotential connection. According to the operating requirements of the all-online discharge test equipment system, after restoring the normal connection of the system, the all-online discharge test equipment exits the service and completes the full online discharge and charging recovery of the 18650 battery 3.7v 3500mahpack. The whole process of normal connection. Another set of batteries is tested for online discharge capacity in the same way. As shown in Figure 4.

　　2.2 Online discharge “seamless connection” technology

　　In order to ensure the safety of 18650 battery 3.7v 3500mahdischarge testing, the 18650 battery 3.7v 3500mahpack's fully online discharge equipment requires a seamless connection when connected in series to the positive electrode of the 18650 battery 3.7v 3500mahpack, as shown in Figure 5.

　　[page]18650 battery 3.7v 3500mahpack online discharge test seamless connection operation, "device" access should comply with "connect three first, then remove one", that is, first connect the power cords L1, L2, L3, and then remove the original power connection line L5; When "equipment" is tested and exited from service, the principle of "connect one first, then remove three" should be followed, that is, connect the original power cable L5 first, and then remove the power cables L1, L2, and L3.

　　3 Comparative analysis of online discharge technology and current discharge technology

　　3.1 Comparative analysis with offline discharge technology

　　(1) The discharge process ensures the backup power of the 18650 battery 3.7v 3500mahpack to the maximum extent and minimizes the risk of system paralysis caused by discharge testing;

　　(2) The 18650 battery 3.7v 3500mahpack can automatically resume charging after being discharged, overcoming the difficulties in operating the equipotential access system after offline discharge and potential safety issues;

　　(3) The electric energy stored in the 18650 battery 3.7v 3500mahpack is utilized to the maximum extent, eliminating the waste of offline discharge energy. There is basically no heating phenomenon, no danger of high temperature, and no impact on the ambient temperature of the computer room;

　　(4) Only perform seamless connection operations on the positive electrode of the 18650 battery 3.7v 3500mahpack to avoid the risk of short circuit caused by improper operation during offline discharge;

　　(5) Once the device is connected in series to the positive electrode of the 18650 battery 3.7v 3500mahpack, and after setting the relevant discharge parameters, all discharge and charging work will be completed automatically, and maintenance personnel can perform other work, reducing work intensity and improving work efficiency.

　　3.2 Comparative analysis with online evaluation discharge technology

　　(1) The full online discharge method can achieve the discharge test purpose of maintaining 18650 battery 3.7v 3500mahactivity during deep discharge and detecting backward batteries, and fully grasp the remaining capacity and backup power supply time of the 18650 battery 3.7v 3500mahpack;

　　(2) Maximize the backup power of the 18650 battery 3.7v 3500mahpack during the discharge process and minimize the risk of system paralysis caused by capacity testing;

　　(3) The full online discharge method can realize group discharge of each group of batteries with the same current, and any backward single cells can be exposed, overcoming the limitations of online evaluation discharge;

　　(4) Once the fully online discharge equipment is connected in series to the positive electrode of the 18650 battery 3.7v 3500mahpack, and after setting the relevant discharge parameters, all discharge and charging work is automatically completed, and maintenance personnel can perform other work, reducing work intensity and improving work efficiency.

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