A Plug-In Hybrid Still Venting in the Salvage Yard
You are called to a salvage yard where a 2022 plug-in hybrid with a 14.4 kWh lithium-ion pack was towed after a fire in an attached garage. The fire began at 02:40, about four hours after the car was parked and plugged into a 120 V Level 1 charge cord running through a 25 ft, 16 AWG extension cord. The garage and the front of the car burned. The underbody around the pack is blistered, and a small flame was visible at a pack vent when you arrived. The car sits 18 ft from other vehicles, and the yard manager wants it moved to the public auction row by noon. The 12 V battery is still connected and the charge cord is still plugged in. The owner says the car had a recall letter about the battery. You have a thermal imager and a four-gas meter, and no high-voltage PPE on site.
1. Set out your safety plan before anyone approaches the vehicle.
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Treat the pack as energized, damaged, and thermally unstable. Lithium-ion packs can reignite hours or days after the initiating event, and a venting pack can jet flame and eject cells. A flame at the vent on arrival means the propagation risk is live, not historical.
Exclusion and fire watch. Establish an exclusion zone of at least 50 ft, keep other vehicles out, and coordinate with the fire department for a water supply and a wet-down plan. Water in volume is the accepted cooling method for a lithium-ion pack; the goal is to cool the pack, not to smother the vehicle.
Do not touch what can hurt you. Do not cut, lift, or probe orange high-voltage cables, and do not cut the charge cord. Have the supply circuit de-energized at the panel and verify with a meter, then separate the connector at the vehicle end only if it can be done without contact with damaged components.
PPE and procedures. Class 0 insulating gloves rated to 1,000 V, arc-rated outer layer, insulated tools, and a second person as safety spotter with the thermal imager. No lone work. Obtain the manufacturer's emergency response guide for this exact model and follow its de-energization sequence.
12 V system and data. Photograph the 12 V connections before doing anything, then disconnect the 12 V per the manufacturer's procedure so the high-voltage contactors open. Monitor pack temperature with the thermal imager at intervals; if it is rising, withdraw and let the fire department handle it.
2. How do you evaluate the competing hypotheses: the extension cord, the EVSE, the pack, and the garage wiring?
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Extension cord and connection. A Level 1 charge draws roughly 12 A continuously. A 25 ft, 16 AWG cord is undersized for that continuous load, particularly if it was coiled, run under a door, or had a worn plug. Resistance heating at the plug and receptacle interface is a classic ignition scenario. Look for cord beading, a melted or discolored plug, arc damage at the receptacle, and whether the EVSE has a thermal cutoff in the plug and whether it logged a fault.
Pack. The recall letter is a lead, not a conclusion. Run the VIN against open recalls, download the battery management system and charge history through the manufacturer, and examine the vent path and underbody for a localized origin rather than diffuse blistering. A pack-initiated fire typically shows a cell-level origin with a directional vent pattern; diffuse underbody damage is more consistent with an external fire below or around the vehicle.
Garage wiring. Examine the branch circuit and receptacle that fed the EVSE: whether it was a dedicated circuit, whether GFCI protection was present, and conductor condition.
Timing. Fire at 02:40, about four hours after plugging in. This is a weak discriminator: a connection fault usually develops within the first hour of a continuous load, and a pack fault can develop over hours, so timing is consistent with both. Do not lean on it.
3. What evidence do you preserve, and how do you handle the yard manager's noon deadline?
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Document before anything moves. A 360-degree exterior series with scale, the underbody, the charge cord and EVSE in their found positions, the VIN, the pack label, and a thermal imager baseline with time stamps. Once the vehicle is moved, the relationship between the cord, the receptacle, and the vehicle is gone.
Preserve the small items. The cord and EVSE go into separate, labeled containers so they cannot contaminate each other, with a full chain-of-custody record. Photograph the plug blades and the receptacle before removal for arc damage. Photograph and preserve the breaker.
Preserve the data. The BMS and charge logs may be the only recoverable evidence of what the pack was doing, so request them from the manufacturer in writing early, with a preservation letter to the carrier and the manufacturer.
On the deadline. I tell the yard manager in writing that moving the vehicle destroys evidence and that I am notifying the insurer. If it must move, it moves on a flatbed with a fire watch, a water supply, no forklift contact under the pack, and a documented chain of custody, with the fire department on notice. I do not let a noon auction schedule dictate the handling of a vehicle that was venting when I arrived.