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May 8, 2026 — Stellantis has taken out a patent on a battery-failure move that sounds more like a military tactic than a safety feature: cut the hot pack loose and roll away on the backup battery. The patent, granted to FCA US, describes an electrified vehicle that can sever its high-voltage battery from the drivetrain when the cells start to overheat, then use the 12-volt system to move the car clear of the danger. The stated reason, per the filing, is to prevent a total loss.
That might sound dramatic, but the economics behind it are real. An EV's high-voltage battery isn't a component: it's the heart of the vehicle's value. When a pack starts generating abnormal heat, the damage cascades quickly — melted bus bars, compromised pack housing, sometimes even to the underbody structure. By the time first responders and tow operators have done their work, the repair cost often exceeds half the car's worth. Insurers total those cars as a matter of routine. This patent is aimed squarely at that routine.
What makes the FCA filing clever is the order of operations. Most thermal-runaway countermeasures focus on containing the event: venting gas, isolating cells, or flooding the pack with coolant. Those strategies try to save the battery. This patent takes the opposite view — that the pack is already a lost cause, and the priority is saving the rest of the vehicle. The controller opens the high-voltage contactors, physically separating the battery from the drivetrain, and then uses the humble 12-volt system to give the car a short burst of low-speed locomotion.
A car driving on 12 volts sounds like a party trick, but it's within the realm of engineering possibility. The 12-volt battery, kept topped up by a DC-DC converter in normal operation, can be routed through the traction inverter to spin the drive motor slowly. Without the high-voltage pack in the circuit, the motor's power is severely limited. The vehicle won't climb a steep grade or merge onto a highway. But it doesn't need to — the whole point is to creep out of a parking garage, off a ferry deck, or to the shoulder of a road where the vehicle is no longer blocking traffic or endangering adjacent structures.
That last part matters more than it might appear. Parking structures are particularly vulnerable. A lithium-ion fire in a confined space can easily spread to neighboring cars, and in buildings with limited ventilation, smoke and gas accumulation create serious hazards for fire crews. Fire departments increasingly treat EV fires as multi-hour events, often requiring specialized blankets or water supplies. A car that can move itself away from the building's structural elements and toward an isolated fire lane reduces the stakes dramatically.
The patent also touches on the insurance industry's least favorite phrase: "declared total loss." When an EV's battery pack is deeply integrated into the chassis, replacing it requires dismantling large sections of the vehicle. Many manufacturers use structural adhesives and welds so thorough that individual modules cannot be replaced in a dealership setting — the repair industry calls this the "brick-and-glue" problem. The cost of a new pack, plus labor, plus the risk of hidden structural damage, quickly adds up. Battery damage has become one of the most common reasons EVs end up as total-loss write-offs.
FCA's interest in this problem is not theoretical. The Chrysler Pacifica Hybrid, the company's first plug-in vehicle sold in volume in North America, went through fire-related recalls over its battery connector and high-voltage cable routing. Those recalls were followed by demanding software and hardware fixes. That experience, plus the move to the STLA platforms, has clearly shaped the way Stellantis thinks about battery safety. The company now holds dozens of patents in thermal regulation and battery isolation, and this filing is among the most explicit: when in doubt, cut the pack loose.
Stellantis is far from alone in this territory. General Motors designed its Ultium packs with carefully tuned vent paths and cell-level monitoring. Tesla has published detailed first-responder guidance that includes cutting specific cables before extracting occupants, and its packs use fire-resistant mica sheets. CATL and LG Energy Solution, the suppliers behind many modern packs, are investing heavily in cell-level fusing and heat-blocking compounds. The FCA patent stands out because it's the rare one that plans for the vehicle's continued mobility after the battery is gone.
The detection side of the system will draw the most engineering attention. The patent's language references temperature thresholds, voltage imbalance across cells, and internal pressure estimates — all signals that can appear minutes before a lithium-ion cell enters thermal runaway. But an over-sensitive system could be a problem. A false trigger that isolates a healthy battery would leave owners stranded and undermine trust in the technology. The calibration challenge is real: the system has to be confident enough to act before a small problem becomes a large fire, without being so twitchy that it converts ordinary driving jitters into a limp-home event.
Patents, as always, are not production commitments. Automakers file hundreds of them every year, and a large share never reaches a showroom. Stellantis has not announced any intention to deploy this particular strategy in a retail vehicle, and the patent could easily end up as a defensive filing — a way to keep competitors from controlling the concept. What it does demonstrate, though, is that the company sees the battery-safety battle as moving from hardware to control software. The next generation of EVs won't just be less likely to catch fire; they'll be designed to behave intelligently after a fire starts.
That behavior is becoming a regulatory and market issue, not just an engineering one. The European Union's updated battery rules push for repairability and state-of-health reporting, and similar conversations are underway at the state level in the U.S. Insurers, meanwhile, are pressing automakers for more serviceable designs: standardized battery service access, module-level repair instructions, and cheaper replacement paths. A patent that keeps a battery event from ending in a scrap yard fits neatly into all of those trends.
For Stellantis, the timing lines up with a critical product wave. The STLA Medium platform underpins new European EVs, while STLA Large is spawning the Jeep Wagoneer S and Dodge Charger Daytona in North America. Both architectures carry large-format battery packs, with some configurations using nickel-cobalt-free chemistries. As those vehicles reach customers in volume, battery-related warranty costs and fire risks become real-world statistics. A safety net that saves the car when the battery fails would have genuine balance-sheet value.
What would that look like in practice? Picture a Wagoneer S parked in a mall garage, its battery management system flagging a climbing temperature in one module. The warning lights up the dashboard, the contactors open, and the driver — or the system itself, if the vehicle has automated parking capability — edges the SUV toward the nearest open corner of the garage. First responders arrive to find a hot battery pack, not a burning building. The owner gets a new pack and a repair bill, not a total-loss settlement. That's the scenario the patent is designed to achieve.
The caveats couldn't be clearer, and the patent text itself reads like a catalog of what could go wrong. A 12-volt-only drive means reduced steering assist and brake assist if the vehicle's power assist is electrically driven. It also means the low-voltage battery will drain quickly, so the system has to budget every watt of movement. The patent's language anticipates these issues by describing a gradual disconnection: the controller doesn't just cut everything at once, it stages the process, making sure the auxiliary systems stay online while the vehicle maneuvers.
That staged approach is what separates a thoughtful patent from a fantasy. The system must decide, in real time, whether it's better to hold the battery and limp home or let go and crawl to a safe spot. It's a curious decision tree for a vehicle to face, but one that will become more common as cars get larger batteries, structural packing, and automated driving features. The FCA patent is a window into that logic, and it suggests that the next generation of EVs will treat the battery not as a sacred unbreakable core, but as a protected, replaceable service item.
Stellantis is already a company that talks about "rightsizing" its EV strategy and delaying some launches to get the details right. This patent is consistent with that mindset: it's not flashy, not marketing-driven, and not meant to sell cars. It's a systems-level insurance policy against the most expensive failure mode in the EV playbook. Whether it ships in a production car in 2027 or 2028, it confirms one thing: the auto industry is finally treating battery fires as a financial problem to be managed, not just a safety problem to be contained.
