Automotive
EV battery nail test evaluates thermal runaway risks during internal short circuits
Engineers use nail penetration testing to measure heat control and battery pack stability under catastrophic mechanical damage.
The short version
- The nail penetration test simulates internal short circuits by driving a metallic pin into an electric vehicle battery cell at speeds up to 1.57 inches per second.
- Outcome severity depends heavily on cell chemistry, with lithium iron phosphate (LFP) displaying higher thermal tolerance than nickel manganese cobalt (NMC).
- Test failures cause rapid thermal runaway, venting toxic gases like hydrogen fluoride and reaching temperatures over 1,500 degrees Fahrenheit.
Key facts
- The nail test drives a metallic object between 0.1 and 0.3 inches in diameter perpendicularly into a battery cell to create a short circuit between the anode and cathode.[Jalopnik]
- Lithium iron phosphate (LFP) cells enter thermal runaway between 520 and 570 degrees Fahrenheit, making them more resistant to puncture-induced fires than nickel manganese cobalt (NMC) cells, which trigger thermal runaway between 300 and 410 degrees Fahrenheit.[Jalopnik]
- Failing cell tests can release flammable fumes and hazardous gases such as hydrogen fluoride at temperatures exceeding 1,500 degrees Fahrenheit.[Jalopnik]
- The mechanical puncture procedure evaluates real-world hazards including high-speed road debris strikes and battery box deformation during vehicle crashes.[Jalopnik]