What Do You Think Of The Several Fires In The Tesla Mega Pack?

Tesla caught fire again, this is the Mega Pack problem, let's look at Tesla's current overall go in the Power Wall and Mega Pack. With the deployment in the United States, but also a bit like the Korean side began to repeatedly fire, this thing I think there are still so many effects: ● Chemical system conversion: Tesla's energy storage, but also began to switch from ternary.

● Chemical system conversion: Tesla's energy storage, also began to switch from ternary to lithium iron phosphate, on the one hand, cost considerations, on the other hand, life and safety considerations.

● Safety system upgrade: Since the energy storage system fire in South Korea, the safety of the storage system has been in front of us, due to the unmanned setup, this problem has no personnel accidents, but repeated fires will also further strengthen the pursuit of safety.

Although there are some safety issues, but overall, the energy storage business has now begun to become a new growth engine, is a very important support business unit for lithium batteries. In the future, on the one hand and the power battery to grab resources, but also an important hedge business version of the battery business.

Part 1

Tesla Energy Storage System Accident and Structure Analysis

In terms of Tesla's energy storage deployment, this data has been moving upwards. In terms of product structure, it is mainly divided into Tesla Power Wall, Power Pack and Mega Pack for individuals, individual businesses and energy operating companies.

Tesla's energy storage system fires, the circumstances of Tesla's previous energy storage accidents include mainly these two in the United States and Australia.

In September, a fire broke out at a PG&E-operated Mega Pack battery project in Monterey County, California, and in April PG&E launched the Elkhorn Tesla Megapack project, consisting of 256 Tesla Megapack battery cells with a total capacity of 730 MWh.

Tesla's Energy Storage Deployment

If we then look at the safety design of the MegaPack set up by Tesla, it does cover the cell, module and system levels.

Security settings for MegaPack

Energy storage power plant accidents caused from the big picture, can be categorized as battery system defects, insufficient redundancy of the protection system for electrical failures, inadequate management of the operating environment, and lack of a comprehensive management system for energy storage systems.

● Battery consideration: This is generally triggered by the battery thermal runaway, the defects of the battery manufacturing process brought out from inside the mother's womb and the degradation of the energy storage system safety brought about by the aging of the battery in two aspects, which is not much due to Tesla's small battery and disengagement mechanism.

● External excitation source factors: mainly include current shocks and external short circuits caused by insulation failure, but also include thermal shocks caused by high temperature heat production of components other than the battery, as well as the thermal runaway spread process triggered by the thermal runaway of a battery.

●Operating environment factors: Don't look at the energy storage is a small current, in fact, the operating environment management is more complex, if not properly managed will gradually affect the reliability of the battery and the system.

There is also the whole digital operation situation.

Part 2

The safety iteration of energy storage system

Tesla from the safety and longevity, but also in the ternary small cells to lithium iron phosphate cells switch. powerwalls, powerpacks and Megapacks will use lithium iron phosphate batteries.

After the change to LFP, the MegaPack becomes 3.9 MWh, an increase of nearly 50% from 2.6 MWh.

 

The first generation of energy storage design: built-in module design, using NCA 18650 cells similar to the Model S module placed side-by-side, into the water-cooled tubes on both sides of the box, the electronic part including the converter and BMS arranged in the front section of the compartment.

And then evolved similar to the module-less solution, making all the cells into one big block by potting mode. The right side is the new design, at the system level to eliminate the water-cooled solution, the battery directly placed together and then bonded together as a whole.

Tesla's design gradually absorbs features of Chinese battery design

Summary: From now on, the development of energy storage has so many preliminary conclusions.

1. high energy density cells also objectively can not afford higher abuse, from the perspective of life and safety, the use of more resistant lithium iron phosphate is a good solution.

2. In most cases, large cells have a natural advantage over small batteries in the field of energy storage. The multiplier situation of energy storage is much smaller than that of automobiles, so it is more advantageous to go the large cell route in terms of efficiency, cost and characteristics.

3. The introduction of integrated thermal management is very helpful for lithium iron phosphate, maintaining a stable temperature, is the key to energy storage life assurance. In extreme cases, the extremely rapid cooling of lithium iron phosphate will also delay potential thermal safety incidents.


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