In recent years, the country has been vigorously supporting the development of the new energy vehicle industry, and the completeness and promotion of corresponding charging infrastructure are important guarantees for the development of new energy vehicles. There are over 1.5 million charging stations had been built, which can meet the charging needs of over 10 million electric vehicles.

Charging piles are used throughout the world and must withstand extreme weather conditions such as wind, rain, sunlight, high temperature, and low temperature. They must also provide sufficient strength to protect internal electrical components from external impacts and have corresponding fireproof, flame retardant, and insulation properties to ensure electrical safety. This poses great challenges to the environmental reliability of the charging pile housing. Currently, there are mainly two types of charging pile housings on the market: sheet metal structures and plastic structures. Due to its high strength, fire resistance, high temperature resistance, and good heat dissipation, sheet metal structures occupy the majority of the market. However, the sheet metal structure charging pile housing material is mainly made of carbon steel sheet, which is prone to rusting. This not only seriously affects the appearance of the product but also affects the product's service life and safety. Therefore, relying solely on traditional sheet metal spraying processing technology is difficult to meet the increasingly stringent environmental reliability requirements of charging pile products, and it is urgent to carry out corrosion protection design for charging stations.

Technical requirements for charging piles:

Charging piles are divided into three types: AC charging piles, DC charging piles, and AC/DC integrated charging piles. DC charging piles are generally installed on highways, charging stations, etc., while AC charging piles are generally installed in residential areas, parking lots, road parking spaces, highway service areas, and other locations. According to the requirements of the State Grid Q/GDW 485-2010 standard, the charging pile enclosure should meet the following technical conditions:

Environmental conditions:

Operating ambient temperature: -20°C to +50°C
Relative humidity: 5% to 95%
Altitude: ≤2000m
Seismic resistance: Ground horizontal acceleration of 0.3g; ground vertical acceleration of 0.15g; the equipment should be able to withstand the simultaneous action of three sine waves for a continuous duration, with a safety factor greater than 1.67.

Environmental Requirements:

The protection level of the charging station enclosure should meet the following requirements: IP32 for indoor use, IP54 for outdoor use, and necessary rain and sun protection devices should be provided.


Three-proof requirements (moisture-proof, mildew-proof, and salt spray-proof): The printed circuit boards, connectors, and other circuits inside the charging machine should be treated to resist moisture, mildew, and salt spray, enabling the charging machine to operate normally in outdoor environments with humidity and salt spray.


Anti-rust (anti-oxidation) protection: The iron shell of the charging station, as well as exposed iron brackets and parts, should be treated with double-layer anti-rust measures. Non-iron metal shells should also have anti-oxidation protective film or undergo anti-oxidation treatment.

Sheet Metal Charging Station Enclosure Structure Features:

The charging station generally consists of the charging station body, charging socket, protective control device, measurement device, card reader, human-machine interface, etc., as shown in Figure 1.

Metal structure of the charging station body is made of aluminum alloy or stainless steel. The processing method involves sheet metal punching, bending, and welding. Some types of charging stations, considering outdoor protection and insulation requirements, adopt a double-layer structure. The overall shape of the product is mainly rectangular, with a welded frame. To ensure an aesthetically pleasing appearance, rounded corners are added in certain areas. Reinforcements or plates are usually welded to ensure the overall strength of the charging station. The external surface of the station body is generally equipped with panel indicator lights, panel buttons, charging ports, and heat dissipation holes. Rear doors or side panels have anti-theft locks, and the station body is fixed to the installation base with anchor bolts. Fasteners are typically made of electroplated carbon steel or stainless steel. To ensure a certain level of corrosion resistance, the charging station is usually coated with outdoor powder paint or outdoor paint to ensure its service life. 

Analysis of Causes of Charging Station Corrosion:

Traditional corrosion prevention processes applied to charging stations should, in theory, meet the requirement of a service life of no less than 8 years. However, feedback from customers indicates that rust and other forms of corrosion occur to varying degrees within one to two years of field service, leading to peeling and fading of the coating. This significantly affects the company's image. After conducting on-site investigations and interviews, a targeted analysis of the locations and causes of corrosion in charging stations was carried out.
The traditional corrosion prevention process alone cannot meet the environmental reliability requirements during the actual service of charging stations. A comprehensive, thorough, and top-down corrosion prevention design is necessary to ensure product quality and meet customer requirements.

Sheet Metal Charging Station Enclosure Corrosion Prevention Design:

Structural Design:

1.Avoid sharp corners on the surface of the charging pile structure.
2.The top cover should have a slope of at least 5° to prevent water accumulation and avoid water seepage and corrosion.
3.For relatively sealed products, use dehumidifiers to prevent condensation. For products with heat dissipation requirements and ventilation holes, use humidity controllers and heaters to prevent condensation.
4.Consider outdoor conditions during welding. Use full welding for external welds. If full welding is not possible, seal the incomplete welds with adhesive to ensure the product meets IP54 waterproof requirements.
5.For sealing welded structures such as reinforcing ribs on door panels, ensure that the coating does not enter the sealed structure. Improve the design by assembling after coating, using galvanized plate welding, or applying electrophoretic coating after welding.
6.Welding structures should avoid narrow gaps and confined spaces that cannot be reached by spray guns.
7.Preferably use assembly design for ventilation holes to avoid small welds and interlayers.
8.Purchase locks, hinges, and other external components made of 304 stainless steel, with a neutral salt spray resistance time of not less than 96 hours.
9.Change the method of fixing the nameplate to waterproof rivets or adhesive bonding. If screws are used for fixing, waterproof treatment must be applied.
10.Use zinc-nickel alloy coating or 304 stainless steel treatment for all fasteners. 
11.Zinc-nickel alloy fasteners should not be used in contact with stainless steel.

12.The installation anchor holes for the charging pile must be pre-processed and not drilled after the installation of the charging pile. After drilling, the dust on the ground should be removed before installation. The bottom entry hole of the charging pile should be sealed with fireproof mud to prevent surface water vapor from entering the interior. Silicone sealant can be applied between the pile body and the cement installation base to enhance the bottom sealing.

Process Design:

From the structural characteristics of charging piles, we can see that there are many welds, interlayers, and semi-enclosed or enclosed structures in most charging pile structures, which pose challenges for process design. To address this issue, three process design options have been proposed:
1.Double-layer powder coating system: Base coat: epoxy anti-corrosion powder (50μm); Top coat: pure polyester weather-resistant powder (50μm); Total thickness: not less than 100μm.
2.Electrophoretic base coat + powder coating system: Base coat: electrophoretic coating (20-30μm); Top coat: pure polyester weather-resistant powder (50μm); Total thickness: not less than 70μm.

3.Dip coating + powder spray system: Base coat: water-based epoxy anti-corrosion primer (dip coating) (25-30μm); Top coat: pure polyester weather-resistant powder (50μm); Total thickness: not less than 80μm.

In conclusion, with the vast territory and diverse climate environments in the world, the adaptability of charging piles to the environment poses a significant challenge. Solving the environmental reliability issues of charging piles has always been a difficult problem faced by domestic charging pile manufacturers. The explosive growth of the charging pile market has exposed various problems: imperfect market access, standards, technical capabilities, and quality control; numerous new players in the industry with insufficient R&D and production accumulation; products of varying quality, high failure rates, and rapid scrap rates, among others. As the "first line of defense" for protecting the safety of charging equipment, if charging pile bodies cannot provide customers with high-quality and reliable performance, it will undoubtedly greatly affect brand quality improvement. Therefore, it is essential to clarify various design requirements in the early stage of product design, combine external application environments and electrical requirements, and systematically and rationally carry out charging pile product design.

As a mainstream product of electric vehicle charging equipment, sheet metal structural charging piles face harsh challenges in actual use in adverse environments. In response to the various problems exposed, through research and investigation, the author found that rust is a common phenomenon in the use of pile bodies. Peak Fasten has been dedicated in designing and making EV charging station enclosure cases for years and has vast experience to solve the rust issues from design to produce. Please feel free to contact us whenever there is plan to make new charging station enclosures or any issues to improve for current model.