After the Uber automatic driving test vehicle just had a fatal traffic accident due to the failure of the auto drive system, a Tesla ModelX in California, USA, caused deflagration after the traffic accident. The owner of the car passed away due to serious injuries after being taken to the hospital.


Industry insiders told reporters that Tesla's impressive performance and mileage data can be said to have been achieved under the premise of radical technology. He stated that during the use of Tesla's 18650 battery, any slight inconsistency in the battery array will create a circulating current inside the battery pack, causing self discharge and greatly increasing battery loss.


He also stated that due to the immature manufacturing process, the yield of the 21700 type battery from Panasonic and Samsung SDI will be lower than that of the 18650 type, while the Model 3 may have insufficient production capacity due to battery module assembly issues, which may be related to this.


Tesla has caused another fatal accident


The Tesla involved in the accident first crashed into the median barrier in the middle of the highway, then into the second leftmost lane. After being hit by a Mazda in that lane, it ultimately collided with an Audi car while driving in the leftmost lane, involving a total of three cars. According to the local traffic police patrol team, the involved Model X caught fire quickly before being hit by two other vehicles.


According to the reporter's understanding, the Model X was severely damaged after the incident, with the front of the car completely destroyed and only the frame burned. Due to a significant number of car batteries being exposed after the accident, road workers were unable to immediately clean up the debris on the road surface. The Health Protection Center summoned engineers from Tesla to evaluate the batteries.


According to data, Tesla is currently the only automotive company that uses 18650 lithium cobalt ion batteries. The above-mentioned battery has a diameter of 18mm and a length of 65mm, and is often used as a battery cell for laptops. Due to the fact that lithium-ion batteries are approaching the power threshold at present, Tesla has been using thousands of batteries to form a battery array and place it under the car as its electric vehicle power source. However, such a design increases the possibility of the battery array being impacted in the event of a collision, which can cause the cells or modules to easily shift, resulting in the detachment and short circuit of the wires used for parallel and series connection, leading to a fire.


In addition, the 18650 battery arrays of Model S and Model X have removed the outermost insulation layer in order to reduce weight and cost. Although the company claims to have excellent battery management systems and battery grouping technology, as well as timely temperature monitoring system technology, frequent accidents indicate that the natural defects of the 18650 battery array are still difficult to overcome.


Tesla suggests that a large amount of water should be used to extinguish the fire after the battery catches fire, and a thermal imaging camera should still be used to monitor the battery's condition within an hour after it has completely cooled down.


The stability of lithium cobalt oxide batteries is questioned


In fact, as early as April last year, a Model X caught fire and exploded after a collision in Guangzhou, causing severe damage to the vehicle. At that time, car owners questioned the quality issues of Tesla Model X vehicles themselves; At the beginning of this year, another Tesla caught fire due to battery issues. So, why has battery technology, which is Tesla's core competitiveness, repeatedly experienced accidents?


Industry insiders told reporters that Tesla's impressive performance and mileage data can be said to have been achieved under the premise of radical technology. He stated that although the consistency of Tesla's 18650 battery was stable in the early stages, the battery array would inevitably experience inconsistent battery decay during use. As long as there is a slight inconsistency, a circulating current will form inside the battery pack, causing self discharge and greatly increasing battery loss.


When it comes to Model 3, he said that currently the yield of 18650 batteries from Panasonic and Samsung SDI is generally above 98%, but after switching to 21700 (the battery array used in Model 3), the yield will be affected due to the immature manufacturing process. The recent reports of insufficient production capacity of Model 3 or related issues.


Previously, Tesla stated that the main production limitation of Model 3 was the assembly of battery modules. Musk stated that there are four "regions" in the production of Model 3 battery modules, and one of these regions has a particularly serious issue. According to reports, a Tesla employee who had worked at a Gigafactory revealed that as early as mid December last year, some parts of the Model 3 battery production were still done manually.


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