Engineers at General Motors are close to finalizing a set of design modifications to the Chevrolet Volt battery pack to prevent later fires in packs that have been severely damaged in accidents.

The updates come in response to two fires in lithium-ion Volt battery packs that were compromised during NHTSA crash tests. The fires occurred days or weeks after the damage occurred, and no injuries occurred.

But the incidents have raised enough concern at the National Highway Traffic Safety Administration that the agency has opened a formal investigation into the battery fires--leading GM to offer loaner cars to any concerned Volt owners.

According to Reuters, the proposed package of updates includes reinforcements to the structure of the 400-pound battery pack, better protection to prevent post-crash leaks in the pack cooling system, and lamination of certain circuitry contained within the pack's internal electronics.

2011 Chevrolet Volt during IIHS crash testing

2011 Chevrolet Volt during IIHS crash testing

Sources say engineers will update executives by the end of this week on what it would take to modify the packs in the 10,000 or so Volts that have been built to date. A cost estimate of roughly $1,000 per pack has not been confirmed by General Motors.

Separately, the U.S. House of Representatives will hold a hearing in January on the incidents, focusing on the question of whether the NHTSA withheld information about the fires.

The Detroit News reports that two separate panels of the House Oversight and Government Reform Committee will hold hearings next month.

A statement from the chairman of the Regulatory Affairs, Stimulus Oversight and Government Spending panel, Rep. Jim Jordan (R-OH), expressed "great concern" over reports that "indicate important safety information may have been omitted in testimony" recently before the panel.

As the Detroit News piece notes without comment, the topic of Volt battery fires did not come up in those hearings.


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