Battery Pack Assembly Process Series 9 - Basic Knowledge of Energy Storage Containers
Battery energy storage systems are mainly divided into: container energy storage, industrial and commercial energy storage, household energy storage and portable energy storage, among which container energy storage occupies a major position. Containers are very suitable for the integration of battery energy storage systems because of their advantages such as convenient installation and transportation, good durability and high strength.
This issue will introduce in detail the basic knowledge about the specifications and dimensions of energy storage containers, transportation methods, code meanings, protection levels, anti-corrosion levels and classification society certification.
01 Overview Of The Specifications And Dimensions Of Energy Storage Containers
The international standard ISO 668 specifies the specifications and dimensions of containers, ranging from 10 feet to 45 feet, and even larger sizes such as 49 feet, 53 feet, and 60 feet are available. Among them, 20 feet and 40 feet are mainly used for energy storage systems. At present, 5MWh energy storage systems are the mainstream products in the market, and most of them use 20-foot containers.
The current common ISO668-2020 series 1 containers can be divided into four categories: A, B, C, and D in terms of external dimensions. The relationship between the schematic diagram and the specific dimensions is as follows:
Type 1A: 40 ft (12 192 mm);
Type 1B: 30 ft (9 125 mm);
Type 1C: 20 ft (6 058 mm);
Type 1D: 10 ft (2 991 mm);
i (spacing) = 3 in (76 mm).
• 1A = 1B + 1D + i = 9125 mm + 2991 mm + 76 mm = 12192 mm;
• 1B = 3D + 2i = 3 × 2991 mm + 2 × 76 mm = 8 973 mm + 152 mm = 9125 mm;
• 1C = 2D + i = 2 × 2991 mm + 76 mm = 6 058 mm.
02 Main Modes Of Transport Of Energy Storage Containers
Container transportation has great advantages. It can expand group units, improve loading and unloading efficiency, and reduce labor intensity; shorten the time of goods in transit and reduce logistics costs; simplify packaging and save the cost of goods transportation and packaging.
The main modes of transport of energy storage containers are: road transportation, rail transportation and water transportation.
Road transportation: suitable for medium and short-distance transportation, with the advantages of flexibility, convenient loading and unloading, door-to-door transportation, and can quickly respond to the deployment needs of energy storage containers at different project sites.
Railway transportation: suitable for long-distance and large-scale transportation, with relatively low costs, and less affected by natural conditions during transportation, relatively stable operation, and can transport energy storage containers to distant places of use or large logistics hubs in a short time.
Water transportation: For long-distance and large-scale transportation of energy storage containers, especially cross-border transportation in international trade, water transportation is one of the important modes. It can make full use of the carrying capacity of large ships and reduce unit transportation costs, but the transportation time is relatively long, and it is more obviously restricted by factors such as port facilities and weather and sea conditions.
03 Meaning Of The Code Of Energy Storage Container
To facilitate container transportation management, ISO790-73 stipulates its "mandatory mark", "optional mark" and pass mark.
The identification mark mainly consists of the container owner code (UES), equipment identification code (U/J/Z), container sequence number (300246), check code (9), etc.
The container type code consists of two characters, the first character indicates the container type; the second character indicates the characteristics of a certain type of container.
The size code also consists of two characters, the first character indicates the length of the container; the second character indicates the width and height of the container.
MAX.GR. (MAX GROSS) indicates the gross weight of the container: 30480KG means 30480 kilograms, 67200LB means 67200 pounds.
TARE indicates the dead weight of the container: 2290KG means 2290 kilograms, 5050LB means 5050 pounds.
All containers with a height of more than 2.6m (8ft5in) should have an overheight mark; all containers with a weight of more than 30.48 tons should have an overweight mark. Such marks are usually set on both sides and ends of the overheight container.
04 Classification Society Certification and Type Test
Classification society certification is an important guarantee for the quality and safety performance of energy storage containers.
Certification content includes: structural strength, fire resistance, moisture resistance, electrical safety, suitability for dangerous goods, etc.
Type test is a key link in classification society certification. It is to conduct comprehensive performance testing and inspection of energy storage container samples in accordance with specific standards and specifications, including but not limited to tests such as vibration, impact, temperature and humidity changes in simulated maritime transportation environments, to verify whether it can withstand the test of various harsh conditions and ensure that there are no dangerous situations such as battery leakage, fire, explosion, etc. during transportation.
05 Protection Level And Anti-Corrosion Level Of Energy Storage Containers
5.1 Protection level
The IP protection level of energy storage containers is generally divided according to GB 4208, such as IP54 (prevent dust from entering and prevent water splashing from all directions), IP55 (prevent dust from entering and prevent short-term immersion in water)
Specific requirements: It is usually required to reach IP54 level or above to ensure that the energy storage container can still work normally under harsh outdoor conditions.
Implementation method: The box body needs to use special materials and design solutions, such as fully sealed welding process to prevent rainwater from penetrating from the top, side walls and bottom; the inlet and outlet are equipped with a double-layer filter system to block dust and particulate matter.
5.2 Anti-corrosion level
The anti-corrosion level refers to the ability of energy storage containers to resist corrosion, mainly based on standards such as CECS343-2013 and GB/T 30790.2-2014.
Specific requirements: Since energy storage containers may experience seawater corrosion in the shipping environment and are installed outdoors, they need to operate stably for a long time, so the anti-corrosion requirements are relatively high.
Implementation method: The anti-corrosion system of energy storage containers is generally divided into three layers: epoxy zinc-rich primer, epoxy micaceous iron paint intermediate layer and aliphatic polyurethane topcoat. The bottom area will also be treated with zinc spraying and asphalt paint to withstand complex working conditions such as rain immersion and chemical corrosion.
