NHTSA Triggers "Thermal Events" In Volt Batteries, Opens Formal Investigation

NHTSA has has opened a formal defect investigation into the Chevrolet Volt, on the grounds that

Intrusion in a crash may damage the battery, which may result in a substantial thermal reaction and fire

We knew that NHTSA was already looking in to this type of defect after an earlier test incident, but the official investigation resume [ PDF] lists three separate thermal events that have occurred as a result of NHTSA tests. Hit the jump for the official explanation of this sequence of events.

On May 12, 2011, NHTSA performed a NCAP side pole impact test, followed by a post impact rollover test on a Chevrolet Volt. In connection with that testing, NHTSA has identified the potential for intrusion damage to the battery
which may result in a substantial thermal reaction and fire. Twenty-one days after the May 12, 2011 testing, delayed thermal heating and pressure release resulted in a fire that consumed the Chevrolet Volt and three other vehicles in close proximity at the test facility.

During the week of November 14, 2011, NHTSA performed follow-up battery-level tests to simulate the incident. NHTSA performed three tests simulating the mechanical damage to a battery pack observed from the first incident. Two of the three tests produced thermal events, including fire. Because of these test results, NHTSA has opened this investigation to examine the potential risks involved from intrusion damage to the battery in the Chevrolet Volt, in coordination with the agency’s ongoing review of the emerging technology involved in electric vehicle

A more extensive NHTSA press release notes

NHTSA is not aware of any roadway crashes that have resulted in battery-related fires in Chevy Volts or other vehicles powered by lithium-ion batteries. However, the agency is concerned that damage to the Volt’s batteries as part of three tests that are explicitly designed to replicate real-world crash scenarios have resulted in fire. NHTSA is therefore opening a safety defect investigation of Chevy Volts, which could experience a battery-related fire following a crash. Chevy Volt owners whose vehicles have not been in a serious crash do not have reason for concern.

GM’s response [via Phil Lebeau/Twitter]:

The Volt is safe & doesn’t present undue risk as part of normal operation, right after a severe crash.

This is the defense that GM has been using throughout this NHTSA/Volt fire investigation, and to some extent it bears a lot of similarity to Toyota’s defense against the test results trumpeted by Professor David Gilbert. The argument is that the investigator is creating defects through conditions that would not exist in normal use. The problem with GM’s position is that the safety protocols it wants NHTSA to follow in order to not prevent these kinds of fires apparently haven’t been circulated. As GM’s spokesman put it last week

We had a process [for draining the battery] internally but I don’t believe it was shared with anyone. The incident with NHTSA raised awareness that we had to develop a procedure and alert all stakeholders.

And based on the fact that NHTSA’s press release on this defect investigation lists the agency’s tips for post-crash safety procedures for plug-in vehicles, it seems that this is its major concern. What’s strange is that GM made quite the fuss about its Volt first responder training (see video at top) when the car was launched. That this issue, and the necessary safety protocol response to it, seemed to slip through the cracks when that program was developed is not encouraging.