Lithium-ion battery fires in homes are climbing fast in New York and London, with fire investigators in both cities tracing most ignitions to the moment a device is plugged in to charge. The FDNY recorded 277 lithium-ion-battery-started fires in 2024, up from 268 the year before, while the London Fire Brigade hit a record number of e-bike fires in 2025. Federal safety officials in the United States have responded with explicit warnings against overnight charging and the use of mismatched chargers, yet the fires keep outpacing the guidance.
Charging-phase fires are outrunning awareness campaigns
The core tension is straightforward: e-bikes, e-scooters, and other micromobility devices are moving into apartments and houses faster than safety habits are changing. When a lithium-ion battery fails during charging, the thermal runaway can send temperatures past 1,000 degrees Fahrenheit in seconds, filling a room with toxic gas before a smoke alarm activates. London Fire Brigade investigators stated in multiple cases that “fire investigation concluded the fire was most probably caused by failure of a charging lithium-ion battery pack.” That language points directly at the charging phase, not storage or riding.
A practical question follows from this pattern. Cities that combine targeted charger inspections with real-time public alerts about overnight charging should, in theory, see faster drops in confirmed charging-phase fires than cities that rely on general awareness campaigns alone. New York has moved toward the inspection side of that equation, with the FDNY conducting shop-level enforcement actions including summonses and vacate orders. London has leaned on public messaging, issuing a Black Friday warning tied to its record e-bike fire count. Neither city has published data isolating the results of one approach over the other, which makes it impossible to confirm the hypothesis with current numbers. The gap itself is telling: without granular charging-phase breakdowns, neither enforcement nor education can be properly evaluated.
What FDNY, London Fire Brigade, and CPSC data actually show
The strongest evidence comes from three primary sources. The FDNY reported 277 lithium-ion incidents in 2024, a rise from 268 in 2023. Those annual totals confirm a persistent upward trend in a single U.S. city, though the department has not published a breakdown showing how many of those 277 fires began specifically during charging versus other phases of use.
Across the Atlantic, the London Fire Brigade’s public dataset on lithium and electric vehicle fires from January 2017 through April 2026 provides one of the longest continuous time series available from any major metro fire authority. The brigade reported a record number of e-bike fires in 2025 and issued a separate warning ahead of Black Friday that year, describing a home scenario in which a battery “burst into flames” while connected to a charger. That testimony, combined with the investigative conclusions citing charging failure, anchors the claim that the charging phase is the dominant ignition window.
On the regulatory side, the U.S. Consumer Product Safety Commission issued a safety alert urging consumers not to use universal chargers with micromobility products due to fire hazard. The CPSC also published separate guidance stating that consumers should be present while charging micromobility batteries and should never charge while sleeping. Both advisories are explicitly charging-centric, reinforcing the pattern that regulators see the plug-in moment as the highest-risk window.
Data gaps that block a clear national picture
Several reporting limitations prevent anyone from drawing a clean national trend line. The U.S. Fire Administration’s NFIRS coding guidance explains how lithium-ion battery involvement is, and often is not, captured in fire incident reports. Misclassification is common because the reporting fields were not originally designed to track battery chemistry or device type at the level of detail these fires demand. No national U.S. extract currently isolates home micromobility fires by charging status, which means the 277-fire count from New York cannot be placed in a reliable national context.
London’s dataset is more granular in time coverage but still lacks public per-case coding of charger type or whether a user was present at ignition. The CPSC alerts cite hazard patterns tied to charger mismatches but contain no aggregated incident-level data linking specific charger models to fire outcomes. That means the federal warning against universal chargers rests on pattern recognition rather than a published statistical analysis consumers can review.
The practical gap for residents is real. Someone living in a New York apartment or a London flat who charges an e-bike overnight has no way to check whether their specific charger-battery combination has been flagged, beyond scattered recall notices or news stories about individual fires. Without a centralized, searchable record that ties charging conditions to outcomes, consumers are left to interpret broad warnings on their own.
What residents can do while the data catches up
Until fire incident reporting and product surveillance improve, safety falls largely on individual choices and building-level rules. Fire agencies and regulators converge on a handful of practical steps that meaningfully reduce risk, especially during charging.
First, only use chargers and batteries that are clearly matched and certified for the device. That means avoiding cheap replacement chargers with generic plugs, even if the voltage and connector appear to fit. The CPSC’s warning about universal chargers is rooted in repeated fire patterns where an overpowered or poorly regulated charger pushed cells beyond their safe operating range. Sticking with the charger supplied by the manufacturer, or a listed replacement specifically approved for that model, keeps the charging profile within the battery’s design limits.
Second, treat charging as an attended activity. That does not require staring at the bike or scooter, but it does mean being awake, in the dwelling, and able to unplug quickly if something goes wrong. Charging while sleeping, or leaving a device on charge while at work, removes the only early intervention most residents can realistically provide. If a pack begins to hiss, swell, or emit a sharp chemical odor, immediate disconnection and evacuation can be the difference between a scorched outlet and a fully involved apartment fire.
Third, choose the charging location with escape and containment in mind. Parking an e-bike in a narrow hallway or directly in front of the only exit can turn a battery failure into a deadly trap. Fire services consistently recommend charging on a hard, non-combustible surface away from soft furnishings and exit routes. In small flats where space is limited, that might mean dedicating a corner near a window or balcony door, or charging in a common bike room if the building provides one.
Fourth, avoid improvised repairs or modifications to battery packs. Many of the most severe incidents investigated in New York and London involve altered packs, do-it-yourself conversions, or cells of unknown origin bundled into homemade housings. Even when these devices work initially, they bypass the engineering and testing that align a pack’s protection circuitry with its charger. If a battery appears damaged, overheats in normal use, or was submerged in water, replacing it with a certified pack is safer than attempting repair.
Finally, building managers and local governments can bridge some of the systemic gaps with straightforward policies. Clear rules on indoor bike parking, dedicated charging rooms with sprinklers, and routine checks for obvious hazards-such as daisy-chained power strips or multiple high-wattage chargers on a single outlet-can all reduce the likelihood that a single battery failure escalates into a multi-unit fire. When paired with targeted tenant education that explains why charging-phase fires are uniquely dangerous, these measures offer a practical complement to citywide enforcement and national regulatory alerts.
Better data would sharpen every one of these interventions. If fire reports consistently logged whether a device was on charge, what kind of charger was in use, and whether the user was present, analysts could quickly identify which combinations of behavior and hardware drive the worst outcomes. Until then, residents in New York, London, and beyond are left to act on the clearest signal available: the moment a lithium-ion battery is plugged in remains the moment when the stakes are highest.
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*This article was researched with the help of AI, with human editors creating the final content.
