Battery cell capacity testing and sorting are essential

On June 24, 2020, China’s State Administration for Market Regulation issued a recall announcement stating that under the situation where the State Administration for Market Regulation initiated a defect investigation, FAW Coach (Dalian) Co., Ltd. recently issued According to the requirements of the Implementation Measures of the Automobile Product Recall Management Regulations, the recall plan was filed with the State Administration for Market Regulation: it was decided to recall the liberation of production from August 14, 2017 to August 31, 2018 from June 30, 2020 CA5020XXYBEV31, CA5040XXYBEV31 two pure electric van transport vehicles, a total of 3196 vehicles.

The reason for the recall is that there is a problem with the power battery provided by Zhihang New Energy. According to the recall announcement, due to problems in the product manufacturing process of the power battery supplier Zhihang New Energy, the consistency of the battery cells in the battery pack is poor, and there are hidden safety risks. Affected by the investigation, FAW Coach (Dalian) Co., Ltd. decided to take recall measures To eliminate potential safety hazards.

Specifically, the power battery mainly has the following three problems:

1. In the battery cell capacity test and sorting process, the ambient temperature around the battery cell directly affects the accuracy of the capacity test.

2. The assembly design of the battery pack is unreasonable, and the arrangement density of the battery cell and the battery cell is too large.

3. Insufficient capacity of temperature control system. In the process of running, charging and parking of the vehicle, the power battery is likely to cause thermal runaway due to poor consistency of the battery cells, which may cause the power battery to spontaneously ignite and have potential safety hazards.

FAW Coach (Dalian) Co., Ltd. decided to split and inspect the battery packs of the 3196 pure electric vans planned to be recalled, and to check in detail whether the single cell voltage data, charge and discharge data, air tightness and appearance of the single cell meet the requirements , And replace the problem cell and battery pack to eliminate potential safety hazards.

In response to the recalled models, FAW Coach (Dalian) Co., Ltd.  provided a series of solutions free of charge to eliminate safety hazards. Specific measures are as follows:

1.After unpacking the battery pack, record the battery voltage data of all battery cells, and replace all batteries with a voltage difference of more than 300mv.

2. After unpacking the battery pack, check the appearance of all single battery cells, and replace all batteries with appearance problems (rust, leakage, etc.).

3. Perform balanced maintenance on batteries with a voltage difference within 300mv, and replace batteries that do not meet the required consistency after balanced maintenance.

4. Battery charge and discharge test and air tightness test are carried out on the battery pack that has completed the balanced maintenance of the battery, and the factory can only be shipped after reaching the factory inspection standard.

5. Optimize BMS (Battery Management System) control strategy to eliminate potential safety hazards.