Fast charging makes lithium battery protection components turn enemies into friends!

Fast charging allows lithium battery protection components to turn enemies into friends. Lithium batteries are currently very high-energy-density and very light batteries. However, due to their very active chemical characteristics, they themselves need to be safely maintained, and a new charging and discharging maintenance circuit has been added. . Mosfet, a key component of the charging and discharging maintenance circuit, also has a certain percentage of short-circuit failures. If the output of lithium batteries is not large, this effect will not be reflected. However, the demand for lithium batteries is huge. In 2014, the global shipment of small lithium batteries reached 5.6 billion. With such a large volume of transportation, even with a probability risk of 1 ppm, there are an average of 5,600 dangerous events per year. Therefore, in addition to the maintenance of the main circuit, a second maintenance has been added to further reduce the risk. Among the components for secondary maintenance, there is generally only one component, the useful one-time disconnection safety, the useful PTC, and a variety of components such as temperature control safety wires. If you have PTC, don’t use fuse. If you have fuse, don’t use PTC. The maintenance devices compete with each other, just as different alleles compete for the same position on the chromosome. However, because the maintenance components are not the overall winner, the coexistence of multiple components can meet different application requirements. However, with the rapid popularity of smart phones and the continuous increase of cell phone battery capacity, the demand for fast charging is increasing. There are currently various specifications such as OPPOVooc specification, qualcomm's QC2.0 specification, and MTK's PumpExpressPlus specification. In the case of fast charging, the current will be very large in the first 30 minutes, reaching about 3A. Under the high current impact of fast charging in the first 30 minutes, along with the increase in heat and temperature, it will change the competitive situation of lithium battery secondary maintenance components, rather than the cooperative mode: PTC+fuse forms a primary maintenance combination. First, the PTC+ fuse has the functions of temperature complementation and overcurrent maintenance. PTC has a temperature maintenance function, but because the temperature is relatively high, the selection criteria are relatively large, the relative overcurrent maintenance ability is weak, and the PTC action speed is slow. The fuse is not sensitive to temperature and cannot be maintained for temperature, but the temperature reduction rate is also very low, so a smaller current standard can be selected, and the moving speed is faster compared with the overcurrent maintenance capability. Secondly, PTC+fuse will be a low-cost production method through UL2054. In the case of high current charging, it is difficult for UL2054 to pass a complete test on a single component, because each component has its own advantages and disadvantages. One is the commonly used PTC. Because the charging current is very large, in order to ensure that it does not move under fast charging and temperature rise, the selected standard must be 12066A/7A. Choosing such a large standard will make it difficult for lithium batteries to pass the UL2054 LPS test, because it is difficult to limit the current within 60 seconds to less than 8A. The second is a commonly used fuse. The biggest advantage is that the temperature is not sensitive. Choosing the 5a standard, u003d5a standard safety pole is conducive to the lithium battery to pass the UL2054LPS test; but because the temperature is not sensitive and does not have the maintenance function, it is difficult to overfill UL20546v/1c and v2c Test afterwards. The third is the three-end wrong edge wire. Although it can maintain the temperature after treatment, the current standard is large, up to 10a/12a, and the LPS test cannot be carried out; and the capital is very high. Fourth, some manufacturers choose the dual IC method, which has a better effect, but the cost is relatively high. If the combination of PTC and fuse is used, firstly, the temperature-insensitive 5A type fuse can easily pass LPS, short circuit and other test items, and secondly, the 12066a/7A type PTC can easily pass the 6V/1C, 6V2C overcharge and other test items. Finally, the maintenance plan of PTC+fuse will be safer than a single component. Combining the two components together is equivalent to adding a primary maintenance on the basis of the secondary maintenance, which adds a layer of protection to the safety of the lithium battery and greatly reduces the risk factors. Disclaimer: Some pictures and content of articles published on this site are from the Internet. 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