ESS failure caused by external auxiliary system failure,
ESS,

▍What is CTIA CERTIFICATION?

CTIA, the abbreviation of Cellular Telecommunications and Internet Association, is a non-profit civic organization established in 1984 for the purpose of guaranteeing benefit of operators, manufacturers and users. CTIA consists of all U.S. operators and manufacturers from mobile radio services, as well as from wireless data services and products. Supported by FCC (Federal Communications Commission) and Congress, CTIA performs a large part of duties and functions that were used to be conducted by the government. In 1991, CTIA created an unbiased, independent and centralized product evaluation and certification system for wireless industry. Under the system, all wireless products in consumer grade shall take compliance tests and those complying with the relevant standards will be granted to utilize CTIA marking and hit store shelves of North American communication market.

CATL (CTIA Authorized Testing Laboratory) represents labs accredited by CTIA for testing and review. Testing reports issued from CATL would be all approved by CTIA. While other testing reports and results from non-CATL will not be recognized or have no access to CTIA. CATL accredited by CTIA varies in industries and certifications. Only CATL which is qualified for battery compliance test and inspection has access to battery certification for compliance to  IEEE1725.

▍CTIA Battery Testing Standards

a) Certification Requirement for Battery system Compliance to IEEE1725— Applicable to Battery Systems with single cell or multiple cells connected in parallel;

b) Certification Requirement for Battery system Compliance to IEEE1625— Applicable to Battery Systems with multiple cells connected in parallel or in both parallel and series;

Warm tips: Select above certification standards properly for batteries used in mobile phones and computers. Do not misuse IEE1725 for batteries in mobile phones or IEEE1625 for batteries in computers.

▍Why MCM？

● Hard Technology: Since 2014, MCM has been attending battery pack conference held by CTIA in US annually, and is able to obtain latest update and understand new policy trends about CTIA in a more prompt, accurate and active way. 

●Qualification: MCM is CATL accredited by CTIA and is qualified to perform all processes related to certification including testing, factory audit and report uploading.

An overall ESS failure caused by an auxiliary system failure typically occurs outside of the battery system and may result in burning or smoke from external components. And when the system monitored and responded to it in a timely manner, it will not lead to cell’s failure or thermal abuse. In the accidents of Vistra Moss Landing Power station Phase 1 2021 and Phase 2 2022, smoke and fire were generated because the fault monitoring and electrical fail-safe devices were turned off at that time during the commissioning phase and could not respond in a timely manner. This kind of flame burning usually starts from the outside of the battery system before it finally spreads to the inside of the cell, so there is no violent exothermic reaction and combustible gas accumulation, and so usually no explosion. What’s more, if the sprinkler system can be turned on in time, it will not cause extensive damage to the facility.The “Victorian Power Station” fire accident in Geelong, Australia in 2021 was caused by a short circuit in the battery caused by a coolant leakage, which reminds us to pay attention to the physical isolation of the battery system. It is recommended to keep a certain space between external facilities and the battery system to avoid mutual interference. The battery system should also be equipped with insulation function to avoid external short circuit.From the above analysis, it is clear that the causes of ESS accidents are the thermal abuse of the cell and the failure of the auxiliary system. If the failure cannot be prevented, then reducing the further deterioration after the blocking failure can also reduce the loss. The countermeasures can be considered from the following aspects:
Insulation barrier can be added to block the spread of thermal abuse of the cell, which can be installed between the cells, between the modules or between the racks. In the appendix of NFPA 855 (Standard for the Installation of Stationary Energy Storage Systems), you can also find the related requirements. Specific measures to isolate the barrier include inserting cold water plates, aerogel and likes between the cells.