Research on Direct Current Resistance,
Current Resistance,

▍Certification Overview

Standards and Certification Document

Test standard: GB31241-2014: Lithium ion cells and batteries used in portable electronic equipment―Safety requirements
Certification document: CQC11-464112-2015: Secondary Battery and Battery Pack Safety Certification Rules for Portable Electronic Devices

Background and Date of implementation

1. GB31241-2014 was published on December 5^th, 2014;

2. GB31241-2014 was mandatorily implemented on August 1^st, 2015. ;

3. On October 15th, 2015, Certification and Accreditation Administration issued a technical resolution on additional testing standard GB31241 for key component “battery” of the audio and video equipment, information technology equipment and telecom terminal equipment. The resolution stipulates that the lithium batteries used in the above products need to be randomly tested as per GB31241-2014, or obtain a separate certification. 

Note: GB 31241-2014 is a national compulsory standard. All the lithium battery products sold in China shall conform to GB31241 standard. This standard will be used in new sampling schemes for national, provincial and local random inspection.

▍Scope of Certification

GB31241-2014 Lithium ion cells and batteries used in portable electronic equipment―Safety requirements
Certification documents is mainly for mobile electronic products that are scheduled to be less than 18kg and can be often carried by users. The main examples are as follows. The portable electronic products listed below do not include all products, so products not listed are not necessarily outside the scope of this standard.

Wearable equipment: Lithium-ion batteries and battery packs used in equipment need to meet standard requirements.

▍Why MCM?

● Qualification recognition: MCM is a CQC accredited contract laboratory and a CESI accredited laboratory. The test report issued can be directly applied for CQC or CESI certificate;

● Technical support: MCM has ample GB31241 testing equipment and is equipped with more than 10 professional technicians to conduct in-depth research on testing technology, certification, factory audit and other processes, which can provide more accurate and customized GB 31241 certification services for global clients.

The testing methods are similar among IEC 61960-3:2017, IEC 62620:2014 and JIS C 8715-1:2018. The main distinctions are as followed:Testing temperatures are different. IEC 62620:2014 and JIS C 8715-1:2018regulates a 5℃ higher of ambient temperature than IEC 61960-3:2017. Lower temperature will make it higher viscosity of electrolyte, which will cause lower movement of ions. Thus the chemical reaction will slower, and Ohm resistance and polarization resistance will become larger, which will cause a trend of DCIR increase.SoC is different. The SoC required in IEC 62620:2014 and JIS C 8715-1:2018 is 50％±10％, while IEC 61960-3:2017 is 100%. The status of charge is very influential to DCIR. Normally DCIR testing result will get lower with increase of SoC. This is related to the procedure of reaction. In a low SoC， the charge transfer resistance Rct will be higher; and Rct will decrease with increase of SoC, so as DCIR.The discharging period is different. IEC 62620:2014 and JIS C 8715-1:2018 requires a longer discharge period than IEC 61960-3:2017. The long pulse period will cause a lower increasing trend of DCIR, and present a deviation from linearity. The reason is that the increasing of pulse time will cause a higher Rct and become dominant.Though JIS C 8715-1:2018 refers to IEC 62620:2014, they have different definitions on high rated batteries. IEC 62620:2014 defines that high rated batteries can discharge no less than 7.0C of current. While JIS C 8715-1:2018 defines high rated batteries are those can discharge with 3.5C.