From Dali to Shangri-La Napa Sea, we crossed the road covering a variety of complex road conditions such as high-speed, mountain roads, low-temperature field roads, and reached an altitude of up to 3200 meters, which is an unprecedented challenge for people and cars, especially a pure electric model. When we all ventured to the Napa Sea, the water road challenge gave us another blow.
Let's take a look at the "water prison" set up this time. Select a river channel with a water depth of about 2 meters, and build a 4mX 8m platform using steel structure in the channel, and the platform is located at a depth of about 80-100 cm underwater.
In addition to the waterproof seal, the corrosion of salt to the metal is also a battery pack must be considered. Long-term driving car driving on the seashore, or driving on the road containing snow melting agent in winter, the salt concentration in the environment is very high, a serious situation, if the salt water corrodes the battery pack, infiltrating the battery, it will cause short circuits and leakage of electricity.
The salt spray test is to test this situation, the battery pack is placed in a high temperature and continuous salt spray environment to test the corrosion resistance. I believe that many people do not know that this test has a high time cost, because of its test cycle, the national standard requirements are 24 hours, and the public's test time is 720 hours, which is really a perverted level of difficulty.
These include the increase in the degree of freedom of mechanical vibration from three axial degrees to six degrees of freedom, the time is extended from 14 hours to 180 hours; the direction of mechanical shock is changed from only vertical direction to three axes, and the acceleration is increased to 4 times the national standard. The acceleration of the scooter has increased to 2-4 times the national standard on both axes. The temperature and humidity alternating test with frost maintains a humidity of 95% throughout the whole process, and the test of low temperature is reduced from 25 °C to minus 35 °C. The salt spray test was upgraded from the salt spray of the national standard for 8 h and stood for 16 h to a total of three salt spray tests, of which the 720 salt spray test was 720 h and the PV1209 was 42 days. The temperature shock test has been increased from 8 hours to 12 hours of cumulative storage. Wading in water waterproof test, the national standard only requires "no leakage, shell cracking, fire or explosion phenomenon; after the test the insulation resistance is less than 100Ω /V", while the public requires "water immersion test with temperature shock, the battery pack is heated to 55 °C±2 °C, the battery pack is submerged in 5 °C±2 °C water for 5 minutes, the above operation is 1 cycle; cumulative execution of 20 cycles". There are also projects such as high and low temperature storage, chemical reagent corrosion testing, paint temperature testing, and long-sequence testing, which are not tested by national standards, and volkswagen has also made extremely strict requirements. This ensures that the battery still performs well under extreme conditions and makes a reliable "heart".