What does it mean for the safety of the power battery not to perform the acupuncture test?

by:CTECHi     2021-08-03

Lithium Grid News: A few days ago, the Ministry of Industry and Information Technology issued a notice for 3 drafts of mandatory standards, one of which is about the GB 'Safety Requirements for Lithium-ion Power Batteries for Electric Vehicles' (hereinafter referred to as GBXXXXX-XXXX). In this opinion In the draft, in addition to canceling all tests at the module level, the requirements for acupuncture have also undergone major changes.

First look at the requirements of GB single battery, overdischarge, overcharge, short circuit, heating, temperature cycle, extrusion, a total of five safety tests, and GB/T31485 -Compared with the 10 test requirements in 2015, 4 items have been reduced. Among them, the acupuncture requirements for single cells are also cancelled in GB.

Let’s take a look at how the cancellation of acupuncture is explained in the preparation instructions of the draft for comments. There are three main reasons: first, the regulations in the access management are temporarily not implemented; second, the two IEC standards do not use acupuncture; third, it is believed that acupuncture does not match the actual failure mode. There are some unclear information here:

The acupuncture test will not be implemented for the time being. Let’s talk about the safety test of the power battery.

First, let’s talk about the access management. In the special inspection items and standards for new energy vehicle products in Annex 3, it does state that 'the acupuncture test will not be implemented for the time beingIn addition, this is temporarily not implemented, why is it 'temporary' and not 'permanent'? Is it possible to resume acupuncture testing in the future? The reason is unclear. This reason seems a bit unclear.

Secondly, IEC etc. do not use acupuncture. This description is relatively incomplete. What standards are included in 'waiting'? Except for the clearly mentioned IEC62660-2, IEC62660-3 does not use acupuncture. what about others? In SAEJ2464, UL-2580 (refer to battery safety test (1)) still has acupuncture test requirements. Although FreedomCAR is not a standard regulation, it also includes acupuncture as a popular test reference method. In addition, almost most of the internal testing standards of qualified companies previously required acupuncture. Therefore, this reason is not very convincing.

The third reason is that acupuncture does not match the actual failure mode. How does it not match? If it is said that the need for acupuncture test can fully replicate the actual failure conditions, this is indeed very difficult, and it is indeed not consistent. However, I am afraid that all test requirements are difficult to fully replicate the actual failure conditions. The test conditions only indirectly reflect the conditions of some typical failure modes extracted from the failure modes. Here we talk about 'modeSimply speaking, it doesn't match, it seems that it is not convincing enough.

But what is more interesting is that in the same GBXXXXX-XXXX thermal diffusion test on battery packs, regarding the selection of the recommended trigger method, 'acupuncture' has appeared as a candidate method.

The above is about some unclear points in the draft for comments. So looking back, the pure electric market is now being pushed forward. The battery energy is getting bigger and bigger. Under the same test conditions, the degree of harm caused by battery failure is also on the rise, such as acupuncture 25Ah, 40Ah, 70Ah, and even For a 100Ah NMC square battery, the Level may go directly from 3 or 4 to 5. At the technical level, there are indeed some ways to improve acupuncture, but often these ways to improve cannot fully take into account the performance of certain batteries, so it takes a certain amount of time to research suitable technical solutions. The greater the energy, the greater the corresponding difficulty. , The greater the responsibility of the company, acupuncture is a big hurdle for manufacturers. Some manufacturers may be fortunate to cancel acupuncture, so that the difficulty of obtaining regulatory certification may be reduced, so that the products can be delivered to customers in time.

What I want to say here is that although acupuncture was cancelled in the draft for comments, it needs to be clearly realized that this is only a test at the level of standards and regulations. Considering the actual product For safety and reliability, manufacturers still have to maintain self-discipline, strict requirements, and can't give up research on acupuncture. After all, passing regulatory tests and meeting actual product development needs are two different things. Besides, access is also said to be 'temporary'. Who can guarantee that it will not change in the future, in the future, or in the future? Moving forward in constant rapid changes, adjustments, and optimizations is a characteristic of our market, and it is also something that many outsiders cannot adapt quickly.

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