Testing Chambers Knowledge

  High Temperature Stress   Basic parameters of  high temperature stress There are two basic parameters of high temperature stress: (1) upper limit temperature (TU); (2) Time (T). In addition, there is another parameter to be considered: ambient temperature (TE), because the variable that really affects the effect of constant high temperature is the difference between the upper limit temperature (TU) and the indoor ambient temperature (TE), that is, the temperature change amplitude (R) (r = Tu – TE)   High temperature stress characteristic analysis High temperature test will cause high-temperature aging, heat accumulation, migration and spread of products. It is a static process or process. This method is to provide additional thermal action to make the products work continuously at the specified high temperature, make the heat spread, accelerate the potential defects of products into faults, and expose them in the form of faults.   High temperature stress-induc...

  Thanks to the warm attention of new energy, the power lithium-ion battery industry has also attracted much attention. Power lithium-ion battery is the power source for tools to supply power. It mostly supplies power for electric vehicles, electric bus, electric bicycles and sightseeing car.   Focusing on the thermal runaway of power lithium-ion battery (mainly high-temperature thermal runaway), this paper discusses various factors affecting the safety of lithium-ion battery, and how to further improve the safety of lithium-ion battery. Three causes of thermal runaway of power lithium ion battery, and some treatment methods and suggestions are put forward.   Heat inducement   Usually, thermal inducement is power battery work in the high-temperature environment, including external fire, poor battery heat dissipation, etc. At external high temperature, due to the structural characteristics of lithium-ion battery, SEI membrane and electrolyte will have analytical react...

  For the ideal lithium-ion battery, the capacity balance will not change in its cycle cycle, and the initial capacity in each cycle should be a certain value. Actually, the situation is much more complex. Any side reaction that can initiate or consume lithium ions may lead to the change of battery capacity balance. This will have a serious impact on the cycle performance of the battery.   There are many factors affecting the cycle life of lithium-ion batteries, but the fundamental reason is that the number of lithium ions involved in energy transfer is decreasing. It should be noted that the total amount of lithium in the battery has not been reduced, but there are less “activated” lithium ions. They are confined in other places or the active channel is blocked and cannot freely participate in the process of cyclic charge and discharge.   Then, as long as we find out where these lithium ions that should have participated in the redox reaction have gone, we can find out t...

  BMS failure mode   The single failure of the battery is not only related to the battery itself, but also related to the failure of the battery management System BMS. BMS failure mode can also cause serious accidents, including the following categories:   BMS voltage test failure causes battery overcharge or over discharge: The voltage test line fails due to poor connection, wire pressing process or contact. BMS has no voltage information and does not stop when charging. Battery overcharge will cause fire and explosion. Most of lithium iron phosphate overcharge above 5V is just smoke, but once the ternary battery is overcharged, it will explode.   Moreover, overcharging can easily lead to the release of gas from the electrolyte analysis in the lithium-ion battery, resulting in battery bulging and even smoking and fire in serious cases; The over discharge of the battery will lead to the damage of the molecular structure of the positive material of the battery, result...

  This paper decomposes studying on the failure mode of power lithium-ion battery system is of great significance to improve the battery life, the safety and reliability of electric vehicles and reduce the service cost of electric vehicles. Various failure modes are considered in the design of power lithium-ion battery system to improve the safety of power lithium-ion battery.   Power lithium ion battery system is usually composed of cell, battery management system and pack system, including functional components, harness, structural parts and other related components. The failure modes of power lithium-ion battery system can be divided into three different levels, namely cell failure mode, battery management system failure mode and pack system integration failure mode.   Cell failure mode The failure modes of cell can be divided into safety failure mode and non safety failure mode. The following points are important for the safety failure of the cell:   1....

  Power lithium batteries are widely used in new energy vehicles because of their high energy density, high voltage, high specific power, good cycle performance, and no pollution. In order to meet the energy and range required for normal driving, the number of batteries is large, and the single cells are generally arranged in series and parallel to form a battery pack to save installation space.   The individual temperature difference is caused by the different heat dissipation environments in the battery pack. Under the effect of thermoelectric coupling, the internal resistance of the battery with high temperature will be reduced, which makes the current flowing through the battery increase, and the state of the single battery charge point becomes more and more uneven, which accelerates the deterioration of the battery pack, and then affects the efficiency and life of the battery, and even has serious safety hazards. Therefore, it is necessary to carry out effective thermal m...

  Environmental Simulation Test is conducted to verify the functional reliability of products during use, transportation and storage. It is to expose the product to natural or artificial environmental conditions to undergo its action, so as to evaluate the performance of the product under the environmental conditions of actual use, transportation and storage, and analyze and study the influence degree and action mechanism of environmental factors.   Environmental simulation test chamber is a method for enterprises or institutions to verify the quality of raw materials, semi-finished products and finished products under the conditions of transportation, handling, vibration, etc. The purpose is to verify whether the materials and products meet the expected quality objectives in R&D, design and manufacturing by using various environmental test equipment. It is widely used in Colleges and universities, aviation, aerospace, military, shipbuilding, electrician, electronics, medi...