A garage fire last week in suburban Houston has been linked to a Fisker Karma plug-in hybrid, but the company quickly noted that the battery remained intact and unplugged -- and did not appear to be the cause.

But if not the battery, then what?

More likely, poor packaging in the engine compartment and exhaust routing generated excess heat. When combined with a fluid leak, that would be enough to create a fire, said Jon Bereisa, CEO of consultancy Auto Lectrification.

Bereisa was chief engineer of General Motors' EV1 and was the systems architect for the Chevrolet Volt, so he knows his way around these sorts of complex problems.

Bereisa has driven the Karma and has nosed around the car's inner workings. When he saw the cramped engine compartment of his test car, he was immediately alarmed.

"That engine is shoehorned into that bay, because they had to use a larger engine, because it was too heavy a car. As a result, there's no room for exhaust routing and heat shielding to route the heat away," Bereisa said in an interview.

Thermal condition

The Karma is "using the hell out of that motor-generator," Bereisa said. As a result, a "thermal condition" would be created under the hood or along the tightly packed exhaust routing path. With that sort of heat, an oil, fuel or coolant leak can cause a risk of fire. A major ingredient in coolant is glycol, itself flammable.

Jeremy Gutierrez, the owner of the Fisker Karma, said he smelled rubber when the fire started, according to an account published by Autoweek.

Bereisa said: "You don't smell rubber with batteries, but you will if it's something on the engine."

Why else wouldn't it be the battery?

Bereisa said the battery pack's state of charge likely was mostly used up during its errand run, so it would take a lot of energy and heat to make a heavy battery pack hot enough to ignite. The compartment would have had to been breached -- unlikely for a car that showed no faults during its drive.

By contrast, the recent Chevrolet Volt crash-test battery pack fires were started when engine coolant splashed across a printed circuit board with live voltage, Bereisa said. When a coolant leak runs across a printed circuit board, it makes a conduction path and creates its own short circuit, making the board hot enough to ignite, Bereisa said. But no such event should have happened with the Karma.

"If the pack were to burn down the car, you would see where it started and reached the [battery] case," Bereisa said.

Like the rest of us, Bereisa is awaiting the fire department's official report, but he says, "There's more odds that it's a conventional, heat-related problem in packaging and heat-related leaks."

Fisker's position

So far, Fisker is denying that its battery pack is at fault for the fire, but has dispatched its own squadron of engineers to reach a conclusion.

Fisker spokesman Roger Ormisher said Thursday the cause of the fire still "has yet to be ascertained."

"There are myriad combustible materials that could be in the garage, in the wheel arch, or picked up on the roadside. They think the source is around the Karma, but they have not determined any cause yet. We have investigative teams, three insurance companies and the local fire chief all with their opinions. There are some question marks," Ormisher said.

Ormisher said he did not want to debate Bereisa's theories, but he said that, "The Karma has been through all regulatory and certification checks."

Robert Baker, the chief fire inspector for Fort Bend County, Texas, told Autoweek that the fire started in the Karma, not elsewhere in the garage.

"Yes, the Karma was the origin of the fire," Baker said. "But what exactly caused that we don't know at this time."

This article was originally published in Automotive News.

So what caused the Sugar Land, Texas, garage fire this week that destroyed a Fisker Karma plug-in hybrid and two other cars?

The local fire inspector told Autoweek that the fire started in the Karma, but said he didn't know the exact cause. On Thursday, EV expert Jon Bereisa suggested to me that the Karma's cramped engine-bay packaging could have created conditions that led to the blaze.

Now Fisker Automotive has fired back, refuting Bereisa's speculation in a detailed statement to Automotive News.

As I noted in a Friday blog, Bereisa said the Karma's tight engine compartment packaging could result in a "thermal condition" and the car's possible inability to diffuse heat away from the engine bay and exhaust system.

Bereisa -- formerly chief engineer of the GM EV1 and systems architect of the Chevrolet Volt, and currently CEO of Auto Letrification LLC -- said: "That engine is shoehorned into that bay, because they had to use a larger engine, because it was too heavy a car. As a result, there's no room for exhaust routing and heat-shielding to route the heat away."

But Fisker says the thermal management of its Karma plug-in hybrid adequately diffuses heat in hot-weather and high-load conditions.

The company says the Karma passed safety certification following, "extreme testing of the vehicle, involving laboratory simulations of thermal incidents and on-the-road tests in extreme climate conditions… No incidents of any kind involving engine systems were found."

'Fully tested'

In the statement, Paul Boskovitch, Fisker director of powertrain, said: "Our technologies and engine design have been fully tested and certified at the highest level."

"It is irresponsible and ill-informed for technology pundits to suggest otherwise in order to secure media attention for unfounded claims," he said.

Bereisa said he doubted that the battery pack was to blame for the fire that burned the garage and house of Karma owner Jeremy Gutierrez.

But Fisker says: "Cooling algorithms have been developed to ensure that, at power off and under certain conditions, the vehicle cooling fan maintains circulation in the engine compartment in order to remove any excess heat.

"Packaging of the engine and surrounding components has been done within competitive benchmark standards and heat protection sleeves are placed on and around all hoses in or near high heat zones. All exhaust components have properly engineered heat shields and maintain the recommended separation distance between the shield, shielded components and affected components."

'Zero flammability'

Bereisa suggested that a fluid leak of gasoline, oil or coolant could have ignited under such hot operating conditions. But while many coolants contain glycol, a flammable compound, Fisker says it is "using DEX-COOL 50/50 coolant with a zero flammability rating, according to the Chevron Manufacturers Safety Data Sheet (MSDS) #10445."

As for the engine compartment layout, Fisker says: "The brake system booster which contains the brake system fluid is in a protected region behind the fender on the 'cold'side of the engine. The power steering pump and fluid are also located on the 'cold'side of the engine, near the front of the vehicle."

In addition, the cooling system of the Karma has been over-engineered to account for potential high-load situations, the company says.

"The engine power required at 125 mph (top speed) is less than 115 kw, well below the maximum capability of the engine for continuous operation. In addition the engine controls maintain a thermal watch of the engine and at a temperature of 117 [degrees Celcius] begins to limit power in order to maintain coolant temperature below this point. This is well below the engine manufacturer's recommended maximum temperature rating of 127 [degrees Celcius]."

The company also said that the engine was designed "using the latest Computational Fluid Dynamic (CFD) software packages."

"Evaluations of the results were performed both by the Fisker Thermal team and external consultants. Testing involved thorough road and lab exercises, including multiple hot weather trips over thousands of miles of incident-free operation in Death Valley and Palm Springs, Calif. Additional testing was also performed successfully at maximum and sustained speeds [125mph] on the Autobahn in Germany."

Wind-tunnel testing also mimicked conditions in the Middle East and Africa, according to Fisker.

This article was originally published in Automotive News

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