Nowadays, battery is widely used in various fields as a storage method of renewable energy. In addition, the research on battery has been deepening, which makes the scope of its application gradually expanded from ordinary electronic equipment, electrical machinery, etc. to the power battery of electric vehicles and important components of aerospace equipment and so on.

The widespread application of batteries is not only the credit of battery safety detection, but also the batteries without various safety technical standards can not be applied to the energy power system of general electronic and mechanical equipment. The batteries in scientific research direction, let alone, safety and stability are placed first. Because the battery test covers a wide range, this paper takes the stability of the battery in the high and low pressure environment as the foothold. Through the introduction and comparison of three products of our company, the relevant knowledge of the high altitude low pressure simulation environment test chamber is presented as far as possible.

Simulation test of high altitude low pressure:

During the transportation of batteries through space transport tools such as aircraft, the altitude will be continuously improved and finally the appropriate navigation altitude will be reached. The oxygen content in the air will gradually decrease, the atmospheric density will also gradually decrease, and the atmospheric pressure will gradually decrease. For this kind of test, it is very important to test on the ground at normal altitude, which saves a lot of cost. The high altitude and low pressure simulation test machine is the best choice, and the most direct feature is to pump the air in the machine cavity through vacuum pump to achieve the effect of simulating the decrease of atmospheric pressure. For the battery providing power, it is necessary to bear the change of pressure difference inside and outside first. It can not make the shell of the battery deform due to the change of external pressure environment, which affects the physical function, and then it is the electronic performance inside the battery. Since there is little material exchange between the battery and the atmosphere, it will not be affected by the change of various gas content. However, the change of pressure may cause the change of the internal structure of the battery, and have a certain impact on the charge and discharge characteristics of the battery, and the high altitude low air pressure has a certain impact on the battery heat dissipation, and even the risk of explosion will occur during the detection process. Therefore, it is of great significance to study the influence of altitude on battery performance for battery development, use and test evaluation.

How to choose the appropriate high altitude low pressure simulation test chamber?

Please refer to the following three general altitude simulated test chambers

1.Altitude Simulation Test chamber

The equipment is a multi-in-one structure, and the door with explosion-proof lock and explosion-proof chain has a very reliable guarantee in the proper test range. This product is designed for battery cell testing, and the volume of conventional models will be relatively small:

• Internal Chamber Dimension W600xD600xH600 mm
• External Chamber Dimension W940xD780xH1620 mm

Therefore, the space of the test site is relatively small, so there is no need to worry about the small internal cavity. If the test scale is large, more testing equipment can be safely added in the limited space. Of course, you can also customize the right volume as needed, which is completely possible. In addition, because the volume of the test chamber is small, in order to ensure the stability of the vacuum state of the inner cavity, the charging and discharging ports are not set at both ends as other machines, but instead, the terminal posts are set inside the cavity. The conventional power supply can reach 220V 1kW, so the charge and discharge adjustment of the cell can be carried out in vacuum state, and the overall function is very perfect, So don’t worry about whether it can complete the UN38.3 related tests, there is absolutely no problem. More importantly, the internal pressure is 101kpa-5kpa. If necessary, this value range can be customized for special needs through adjustment. We are professional, so please feel free to buy our products.

2.Walk in Chamber for Altitude Simulated Test

Compared with the previous test chamber, the model of this test chamber is only different in volume and weight. The specific important functions are consistent, and can be purchased or customized according to the needs.

There are two general models:

• BE-8203-5m ³

          Internal Chamber Dimension W1600xD2400xH1300 mm

          External Chamber Dimension W2050xD2700xH2200 mm

          Equipment weight Approx    6 ton

• BE-8203-12m ³

          Internal Chamber Dimension W2000xD3000xH2000 mm

          External Chamber Dimension W2450xD3300xH2900 mm

          Equipment weight Approx   9 ton

This product is mainly designed for the test of battery pack and system. Because the volume and weight of battery pack and system will be relatively large, a chamber with proper volume and weight is needed. The larger inner cavity of the machine provides buffer space for explosion when testing battery pack or system. At the same time, in order to facilitate the placement and removal of battery pack and system, a slide rail can be installed at the bottom of the inner cavity. The product also uses vacuum pump to extract air from the cavity for pressure reduction. Different from that, the charging and discharging interface is set at both ends of the machine, and the protection measures for air pressure leakage are added. The power supply can reach 380V 6kW generally. The data can be monitored through internal signal interface. The normal specification is these, the specific parameters can be customized according to the needs of the test object.

3.Combined Altitude & Temperature Environmental Test Chamber

There are many models of this equipment, which are different weight and volume parameters. You can click the product link to learn more about it. The equipment is more important to increase the function of temperature control based on the simulation of high altitude low pressure. The maximum temperature control range is -70 ° C～150 ° C. We choose emason from the United States, bock in Germany and Tecumseh in France, which has remarkable effect on temperature control. The simulated height of air pressure can be adjusted, which can be controlled at 101kpa-0.5kpa, and the special test requirements larger than 101kpa can be realized by customization. In addition, the temperature control can provide an extreme test environment for the test object under different air pressure simulation, and can test more and more detailed data. Therefore, it is mostly used in aerospace, electronics, national defense, scientific research and other industrial fields of electrical and electronic products, even covering the testing of components, materials and instruments. Because of the function of temperature control, the risk of explosion during test will be greatly improved. We have optimized the safety design of the product. Smoke outlet is set on the top of the machine, and the explosion-proof lock is reinforced. The explosion-proof chain is strong enough. At the same time, the temperature inside the chamber will deviate from the temperature outside the chamber during the test, and frost and condensation will occur on the observation window. We have set up the door frame electric heating device around the observation window, and the situation in the cavity can be observed during any test. Of course, these are only the function brief introduction of conventional models. If there is special test demand, Guangdong bell Test Equipment Co., Ltd. has more than 15 years of experience in manufacturing test equipment, and will meet your needs.

Above are three kinds of high altitude and low pressure simulation test chambers in our company. If your company needs a low altitude air pressure simulation test chamber, this can be used as a complete guide to determine the best high altitude low pressure simulation test chamber on the market. DGBell is pleased to provide a fully customizable high altitude low pressure simulation test chamber designed to meet your requirements. If special customized test chamber is needed, please communicate with our foreign trade staff in time. We will express the requirements with the engineer as soon as possible. Then the engineer will configure and specify customized options according to your ideas to change the existing normal test room regularly or layout the fully customized test room to match your evaluation parameters. Please choose our Guangdong Bell Test Equipment Co., Ltd,that will be a nice try and a good deal.

So far, there are still a lot of people think that the temperature shock and temperature cycle test process and principle of the difference is not big, are to raise or drop the temperature of the test product test; Some people are cheated by the testers because they don’t know enough about the differences between them. If you think there is no difference between temperature shock and temperature cycle, you are wrong. How much do you know about the difference between temperature shock and temperature cycle? Now let’s look at the differences in definition, purpose, application area, and effect.

How much do you know about temperature shock?

Definition of temperature shock

Thermal shock test is often called temperature shock test or temperature cycle, high and low temperature cold and hot shock test. Temperature shock According to GJB 150.5A-2009 3.1, temperature shock is A sharp change in the temperature of the atmosphere around the equipment. The temperature change rate is greater than 10 degrees/minute. Temperature shock test temperature rise/drop rate is not less than 30℃/ min. The temperature variation range is very large, and the test severity also increases with the increase of the temperature change rate. The two-slot test device is allowed to be used in the temperature shock test. Temperature cycle test using a single tank test device. In the two-groove box, the temperature change rate should be greater than 50℃/ min.

Purpose of temperature shock test

The engineering development stage can be used to find product design and process defects, product finalization or design identification and mass production stage can be used to verify the adaptability of the product to the temperature impact environment, to provide a basis for design finalization and mass production acceptance decisions; When applied as environmental stress screening, the aim is to eliminate early failures of the product.

 Application of temperature shock

Temperature changes are common in electronic equipment and components. When the device is not energized, the inner parts of the device experience temperature changes more slowly than the parts on the outer surfaces. Rapid temperature changes can be expected under the following conditions:

— When equipment moves from a warm indoor environment to a cold outdoor environment, or vice versa

— When the equipment is caught in the rain or immersed in cold water and suddenly cools

— Mounted in external airborne equipment

— Under certain transportation and storage conditions

After energizing the device, there is a high de temperature gradient. Due to the temperature change, the component will undergo stress. For example, near a high-power resistor, radiation will cause the surface temperature of the adjacent component to rise, while the rest of the component will remain cold. When the cooling system is energized, manually cooled components undergo rapid temperature changes. It can also cause rapid temperature changes of components during the manufacturing process of the equipment. The number and magnitude of temperature changes, as well as the time interval, are important.

The effect of temperature shock

The impact of temperature shock is usually more severe on the part close to the outer surface of the equipment, and the further away from the outer surface (depending, of course, on the properties of the relevant material), the slower the temperature change, the less obvious the effect. Transportation boxes, packaging, etc. also reduce the impact of temperature shocks on enclosed equipment. Dramatic temperature changes may temporarily or permanently affect the operation of equipment. Here are some examples of problems that can arise when equipment is exposed to temperature shocks. Consider the following typical questions to help determine if this experiment is applicable to the equipment under test

(1) Typical physical effects: broken glass containers and optical instruments; The moving parts are tight or loose; Cracking of solid pills or charge columns in explosives; The shrinkage or expansion rate of different materials, or the induced strain rate is different; Deformation or rupture of parts; Surface coating cracking; Leaky cabin; Insulation protection failure

(2) Typical chemical effects: separation of components; Chemical reagent protection failure

(3) Typical electrical effects: changes in electrical and electronic components; Electrical or mechanical failure caused by rapid condensation or frosting; Electrostatic excessive

The product is suitable for the safety performance test of electronic components to provide reliability test, product screening test, etc. At the same time, through this equipment test, the reliability of the product can be improved and the quality control of the product. High and low temperature impact test chamber is aviation, automobile, home appliances, research in areas such as the necessary test equipment, test and determine the electrician, electronics, automotive electronics, materials and other products, in the high and low temperature test the temperature of the environment impact parameter and the performance after the change, use flexibility, suitable for schools, factories, military industry, research, etc.

Now that we have a brief look at temperature shocks, let’s look at a few things about temperature cycles.

What is the temperature cycle?

The temperature cycle is to expose the test sample to a set of alternating high and low temperature test environment. In order to avoid the impact of temperature shock, the temperature change rate during the test must be less than 20℃/ min. At the same time, in order to achieve the effect of creep and fatigue damage, it is recommended that the test temperature cycle be 25℃ ~ 100℃, or the cycle test of 0℃ ~ 100℃ can be used according to the purpose of the product, and the exposure time is 15 minutes each.

Purpose of temperature cycle test

In order to investigate the resistance and adaptability of the test sample when suddenly subjected to drastic changes in temperature. This experiment generally uses a rapid temperature change chamber or a temperature cycle chamber.

The principle of temperature cycling

The drastic change of temperature is accompanied by the drastic change of heat, and the drastic change of heat leads to the drastic change of thermal deformation, which leads to the drastic change of stress. When the stress exceeds the ultimate stress, there will be crack or even fracture. Rapid temperature test is to investigate the creep failure of components, and its intensity is not as severe as temperature shock test, so it can be used as stress screening.

The difference between temperature shock test and temperature cycle test is mainly due to the different stress loading mechanism. The temperature shock test mainly investigates the failure caused by creep and fatigue damage, while the temperature cycle mainly investigates the failure caused by shear fatigue. Temperature shock test allows the use of two tank test device; Temperature cycle test using a single tank test device. In the two-groove box, the temperature change rate should be greater than 50℃/ min. Therefore, the fundamental difference between the temperature cycle test and the temperature shock test is that the temperature conversion is carried out at a constant rate.

Generally, the rate of change above 5℃/min can be considered as a rapid temperature change test. The temperature shock is to realize the exchange of high temperature zone and low temperature zone within the specified time. The general AIR-AIR test method requires the switch of temperature zone within 20S. The outlet temperature of the test chamber can be stabilized within 5min, and the sample temperature can be stabilized within 15min.

It can accurately simulate the complex natural environment of low temperature, high temperature, high temperature and high humidity, low temperature and low humidity. It is suitable for reliability testing of products in plastic, electronics, food, clothing, vehicles, metal, chemical, building materials and other industries. 2. The temperature cycle test chamber can provide a high temperature and humidity environment to compare the material changes of rubber and plastic before and after the test and the degree of strong decay reduction; It can also simulate the container environment to detect the fading and shrinkage of rubber and plastic under high temperature and humidity.

The machine is specially designed to test the heat resistance, cold resistance and moisture resistance of various materials. The temperature shock is mainly used in the furnace heat test and heating test in the battery safety performance test, but compared with the temperature cycle test box, the temperature shock test box has no humidity.

In recent years, with the power battery set off a boom, the safety of power battery has been concerned. Many people wonder know more about the safety of power batteries. In addition to needling tests, what other tests have power batteries been subjected to? What are the important effects of different tests? Let’s find out.

As a matter of fact, whether it is lithium battery or battery, due to the particularity of its application field makes people’s requirements for the safety performance, reliability and cycle life of the battery more and more high, power battery production process is long, in addition to more than 50 production processes, It also includes battery charge/discharge performance test, battery cycle life test, battery capacity test, quality assurance delivery/incoming testing, production testing and other testing procedures. On the basis of improving manufacturing technology, we must also pay attention to battery product performance test.

Important power battery test items:

1、Crush test: to ensure the safety of life in collision accidents

First of all, extrusion test is an indispensable and important project of power battery test. It can simulate the collision of the car and test the safety performance of the power battery under the condition of extrusion deformation of the power battery. Of course, different countries have different standards for power batteries, and China’s national standards are strict for extrusion test: power batteries can be deformed up to 30%, and no fire or explosion can occur within one hour.

Power battery in the automotive field must also ensure a certain degree of safety, in some traffic accidents do not explode, do not fire, can ensure that the owner from secondary injury, but also in the maximum protection of the owner’s life and property safety, this is today BYD and other emerging new energy vehicles for power battery safety requirements.

2、Overcharge test: designed to prevent charging system failure

Due to the failure of the charging system, the battery continues to charge under the condition of full charge, resulting in overcharge, which leads to the spontaneous combustion of the power battery has happened many times.

The stronger the anti-overcharge ability of the power battery, the lower the chance of spontaneous combustion accidents. The overcharge test can simulate the condition of overcharge to detect the thermal runaway ability of the battery. The overcharge test needs to be applied to the thermal diffusion testing machine. The thermal diffusion testing machine can not only choose the overcharge mode, but also choose the heating mode for testing! Of course, in different countries, the standard of power battery is not the same, and China’s national standard requires the termination of charging with 1 rate current constant current to 1.5 times of the termination voltage, and observation for one hour shall not appear fire, explosion phenomenon. It is necessary to reduce the probability of spontaneous combustion caused by overcharge with a higher anti-overcharge standard, so as to improve the safety performance of various devices, machines, vehicles and ships that apply power batteries.

3、Forced cell thermal control: the whole package is still sitting

Thermal runaway is the trigger for power battery of spontaneous combustion and thermal runaway is often because lithium-ion batteries in the extrusion deformation, puncture or high temperature burning led to the destruction caused the diaphragm is negative short circuit, or due to external short circuit batteries, lithium ion battery within a short period of time accumulated a lot of heat, cause is the cathode active material and electrolyte decomposition, Lithium-ion battery fire and explosion, a serious threat to the user’s life and property safety. Take the forced thermal runaway test of BYD’s blade battery as an example. The thermal runaway of a single battery in the battery pack was artificially caused, and the safety performance of the whole battery pack was observed.

With the self-insulation and flame retardant system of the blade battery, there is no thermal runaway of the adjacent cell. The maximum temperature of the nearby cell is 80°C, which does not reach the temperature condition of thermal runaway of the lithium iron phosphate battery. Thermal runaway in a single cell does not trigger a chain reaction in neighboring cells, so the safety of the whole pack remains the same.

4、Furnace temperature test: bake power battery high temperature safety barrier

Furnace temperature test, also known as heating test, is mainly used to test the safety performance of power battery under high temperature conditions. Of course, in different countries, the power battery standards are different, and China’s national standard requires that the power battery be heated to 130°C by continuous heating, and maintain the temperature for 30 minutes, during this period, the power battery can not fire, explosion phenomenon. And the blade battery using lithium iron phosphate material, high temperature performance is more excellent. In case of fire and other conditions, the super high temperature resistance of the blade battery can also be enough to ensure the safety of the battery to the maximum extent in the high temperature environment.

5、Drop test: to investigate the ability of the power battery to resist accidental impact

Most of the batteries on the market need to pass the UN38.3 test project. UN38.3 requires that lithium batteries must pass the height simulation, high and low temperature cycle, vibration test, impact test, 55℃ external short circuit, impact test, overcharge test and forced discharge test before transportation, in order to ensure the safety of lithium battery transportation. If the lithium batteries are not installed with the equipment and each package contains more than 24 cells or 12 cells, a 1.2-meter free drop test is also required. UN38.3 is designed to make batteries better transported by sea, land and air to various countries and regions.

During air transportation, batteries are prone to short circuit in the environment of sometimes high temperature and sometimes low temperature. The turbulence in the air will make the batteries collide with each other, and the vibration caused by take-off and landing will also have a certain impact on the batteries. The battery contains chemicals and environmental uncertainties, which also require the battery to undergo UN38.3 tests before being airlifted. Batteries are packaged differently because of the way they are shipped by air. Under normal circumstances, there are three types of battery shipment: separate shipment of batteries, shipment of batteries with the product package, and shipment of batteries installed in the product. However, the 1.2m drop test report is only required in the third case, and the other two methods should be provided. Especially when the batteries are shipped separately in the card slot, the batteries are dangerous goods, so the requirements are more stringent.

The battery drop test needs to be applied to the corresponding battery drop testing machine, which is dedicated to testing the damage of product packaging when it falls, and evaluating the impact resistance strength during transportation and handling process. Adopt double column guide, height drop times can be set, the work is stable and reliable, can realize the edge, plane, Angle drop, meet GB/ T48575-92, ISO2248-1972E. Battery drop testing machine generally adopts photoelectric control, can freely choose the drop height, drop release using electromagnetic control, can make the sample instantly free fall, the edge of the packaging container, Angle, plane drop impact test.

In fact, this article only covers five of the most important power battery tests. We will update this knowledge on the rest of the battery tests, you will also stay tuned to our blog if you’re interested.Last but not least, there is a wide variety of devices in the market for testing the safety of power batteries, which should be carefully selected according to the actual test requirements and conditions. For example, the selection of extrusion testing needs to be applied to the extrusion needle testing machine, vertical cell extrusion testing machine, horizontal battery extrusion testing machine, extrusion needle all-in-one machine, horizontal battery pack extrusion needle testing machine and other testing machines. But how do these machines pick and choose? Don’t worry, Guangdong Bell Experiment Equipment Co., Ltd. has all the special safety testing equipment for batteries and special environmental testing equipment for new energy. In addition, we also provide one-stop quality service for you. We are looking forward to your visit.

The Nail Penetration Test, an internal short circuit test method, is a safety test that tests the internal short circuit tolerance of lithium-ion batteries.

The Needle Penetration Test is a test that uses a steel nail through the battery to simulate an internal short circuit to confirm whether the battery is smoking, catching fire, or breaking. In addition, the needling test is not only a test to confirm the safety of the battery, but also a test to understand the basic nature of the battery.

In the normal state, the positive and negative electrode sheets of a lithium-ion battery are insulated by a polymer insulating film – the diaphragm – in the organic electrolyte. In this state, a steel nail is inserted in the lithium-ion battery to create a short circuit between the positive and negative electrode plates, forcing an internal short circuit test. The test method is characterized by the ability to adjust the test conditions such as the diameter, material, insertion depth, insertion position and insertion speed of the steel nail inserted inside the battery.

The Dangers of Nail Penetration

The need for lithium-ion batteries to be tested with a pinprick means that they are extremely susceptible to internal short-circuiting and will be in a very dangerous condition if a short-circuit occurs. Lithium-ion batteries have the characteristics of high energy density, low internal resistance, and high allowable through-current, making them very dangerous. Generally speaking, an internal short circuit occurs during the use of the battery because the manufacturing process is mixed with conductive foreign matter, or by external impact or stress.

In reality, once the product is manufactured, it is difficult to take measures for internal short circuits in the control system, including battery charging and discharging, and circuitry. When an internal short circuit occurs, the battery passes a huge short-circuit current internally, which subsequently generates Joule heat, and this heat, in turn, causes the combustible organic electrolyte to react and produce high-temperature gases, resulting in an increased likelihood of thermal runaway.

When thermal runaway occurs, smoke, fire. In severe cases, rupture occurs, endangering the personal safety of the user. From the user’s point of view, it is important to ensure the safety of the battery for the application of lithium-ion batteries Pinprick testing uses steel nails inserted inside the battery to create an internal short circuit between the positive and negative electrodes in a relatively simple manner. However, when the nail is inserted into the battery to form a perforation on the surface of the battery, this hole will release high temperature gas, resulting in a change in the internal heat dissipation state of the battery, and there may be differences from the actual internal short circuit situation.

Short circuit test without forming perforations and no gas ejections 

It is called Blunt Nail Test (BNT). This method creates a short circuit between the electrode materials (positive and negative electrode sheets) of the battery by the pressure of the nail, and the battery is only slightly deformed after the test. Compared with the usual pinprick test, this method can create a state that is closer to the actual internal short circuit.

Preparation of the experimental setup

To perform this test, manually driving a nail into a lithium-ion battery is definitely not an option and should not be attempted lightly – the nail could fly out and cause injuries to hands and body. Therefore, it is necessary to build a pinning test machine. Using a commercially available benchtop hand press (hydraulic pump required separately, maximum pressure 4000kg, stroke 120mm, stroke extension 250mm long), a nail penetration tester was made that can fit 3 diameters of steel nails (φ3mm, φ5mm, φ8mm, 100mm long). Or you can purchase DGBELL’s nail penetration tester directly, and DGBELL’s nail penetration tester can be manufactured according to your requirements.

Safety measures

Considering the safety, you should make sure the tester can be operated from a certain distance, install the hydraulic pump elsewhere, and add a nail insertion jig to the head of the stroke extension bar to fix different size nails. Insert the nail into the fixture, adjust the position and then use the bolt to fix it. The speed of nail insertion, after several manual hydraulic tests, we obtained the result of about 0.7mm/s by measuring the stroke and movement time.

Test summary

The positive and negative battery terminals were connected to an oscilloscope through an observation probe to observe the voltage waveform. The waveform was observed using a general-purpose memory recorder (Nikkei Electric 8855 model), and the observation probe was connected to the voltage and current unit (8951) installed in the memory recorder.

Related notes

Here, we test three different types of stacked batteries (300mA-h, 1000mA-h, 2000mA-h). The data to be measured are as follows.

– Battery terminal voltage variation over time

– Temperature of the cell surface presented by thermal imaging

– Changes in the appearance and shape of the battery after needling (confirmed by the naked eye) Before conducting the experiment, carefully prepare fire prevention measures and safety measures: prevent splashes, shade the area around the test machine, place a fire extinguisher nearby, etc.

Measurement of the voltage waveform

For batteries with different capacities, use steel nails of different diameters for the pinprick test. The change of terminal voltage over time was measured after the nail penetration test of a 2000mA-h laminated battery using a φ5mm steel nail.

Differences caused by needling conditions

Including the above test results, the following facts are known based on the results of several experiments.

(1) At the point of needling, the terminal voltage drops sharply and gradually decreases to 0V, and the voltage curve fluctuates sharply when the voltage drops to a certain level.

(2) The test results of different battery types and needling conditions vary during the phase from the point of needling to the large change in terminal voltage, but the terminal voltage drops to 0V after 10 to 20s.

(3) For the same capacity battery, the thicker the pinning, the greater the change in terminal voltage when conducting the test. Battery surface temperature measurement After pinning, the change in surface temperature of the laminated battery with time can be measured by infrared thermography. The change in surface temperature measured when the 2000mA-h laminated battery is pinpointed using a steel nail of φ5mm.

Temperature rise after needling The temperature exceeded 200°C during the needling test of a 2000mA-h stacked cell using a φ5mm steel nail. In the test on the 1000mA-h battery sample, a fire occurred when a φ3mm nail was used. In the pin prick test with a φ5mm nail, the fire was observed and the battery temperature increased significantly. Moreover, the maximum temperature measured was below 100°C for different cells.

Although the tester is not a commercial level and can only be used for experimental purposes, it is possible to perform pinprick tests on batteries using this tester. It is also possible to use a general-purpose memory recorder, a digital oscilloscope, and an infrared thermal imaging camera to measure the voltage and temperature of the battery terminals after needling. This test, by short-circuiting the positive and negative terminals, instantly converts the electrical energy stored inside the battery.