Introduction to Battery Testing

     The IEEE1725 standard divides the mobile phone lithium-ion battery system into four sections, namely the cell part, the battery pack part, the host device part and the battery charger part. Among them, the cell part is also the top priority of the IEEE1725 standard.
      The IEEE1725 standard requires a comprehensive review and inspection of the safety performance of the cell, which can be divided into three aspects: document review, manufacturing site review and finished cell testing. The IEEE1725 standard has required that the cell must pass the UL1642 test, so the test clauses contained in UL1642 are not required to be tested in the IEEE1725 standard. Despite this, there are still 14 clauses for finished cell testing in the IEEE1725 standard.
      Most lithium-ion cell standards only stipulate finished product testing and do not disassemble the cell, but among the 14 test clauses required by IEEE1725, there are several clauses for disassembling the cell to measure or observe short circuit prevention. Such as overhang measurement between the diaphragm and the pole piece, and between the positive and negative pole pieces.
      In the IEEE1725 battery standard, there are several test items with clear requirements that appear in this type of standard for the first time. For example, the pressure test of the explosion-proof valve of the finished battery requires drilling a hole on the surface of the finished battery, inserting a needle connected to the air source, and then sealing and pressurizing. When pressurizing, the pressure is required to be stepped, increasing by 5psi each time, maintaining the pressure for 5 seconds, and then pressurizing by 5psi again and maintaining the pressure for 5 seconds, and accumulating until the explosion-proof valve ruptures. This test item requires very precise pressure-pressurizing equipment, including drilling holes on the surface of the battery cell (the battery shell wall is thin), needle sealing (the upper limit of pressure must be at least 230psi), and pressure control during the pressurization process (only 5psi can be increased each time and the pressure is maintained). It is understood that at present, only Shenzhen MORLAB has this complete set of qualified testing equipment in China, and the pressure accuracy can be controlled at ±0.7psi.