Insulation and Voltage Withstanding Powder Coating Solution for New Energy Vehicle Electric Drive Housings

1. Background

New energy vehicle battery cases, motor housings, and electronic control enclosures require coatings that provide excellent dielectric strength and resistance to electrolyte and humid heat, ensuring high-voltage safety. With pinhole-free thick films and superior dielectric properties, powder coating has become the preferred process for surface insulation of three-electric-system housings.

2. Applicable Components

• Battery lower cases, battery end plates

• Drive motor housings, end covers

• On-board charger and DC/DC converter metal enclosures

• Electric motorcycle battery compartments

3. Solution Configuration

Insulating Powder Electrostatic Spraying System
Use high-dielectric-strength epoxy or epoxy-polyester insulating powder with a film thickness of 150–250 µm. Spray guns are configured with special flat nozzles and low-velocity modes, utilizing multi-pass or reciprocating spraying to ensure pinhole- and bubble-free coatings in housing grooves and weld seams. Robot trajectory programming precisely controls overlap areas to guarantee uniform film thickness.

High-Precision Powder Supply and Cyclone Recovery
The powder center is equipped with dense-phase pumps, delivering powder output stability with <2% fluctuation to ensure consistent thick-film build-up. The recovery system uses anti-static filter cartridges to prevent fine powder accumulation that could pose a short-circuit risk.

Long-Cycle Low-Temperature Curing and Insulation Testing
Curing adopts a low-temperature long-bake (150–160 °C, 40–60 minutes) or stepped temperature process for thorough deaeration. Post-line inspection deploys high-voltage insulation withstand testers (2500 V DC) and pinhole detectors for 100% inspection, ensuring coating breakdown voltage >5 kV and insulation resistance >100 MΩ.

4. Solution Advantages

• High Insulation Reliability: Pinhole-free coating, resistant to voltage and electrolyte

• Good Thermal Conductivity and Protection: Combines insulation with adequate heat dissipation to protect the housing

• Environmentally Friendly: Zero VOC, no solvent residue, meeting battery workshop cleanliness requirements

• Efficient Production: Forms thick film in one application, eliminating multiple dip-coating steps

5. Typical Application Case

A power battery manufacturer adopted a powder insulating coating solution for the interior and exterior walls of battery cases. After passing 1,500 hours of humid heat and salt spray testing, breakdown voltage remained stable above 6 kV. The line rate reached 30 JPH, completely replacing insulating paint.