Garages used to be a predictable fire problem. Gasoline, paint thinner, oily rags, a space heater running too close to a stack of cardboard. Those risks have not gone anywhere.
But walk into a typical garage now and count the lithium ion batteries. An e-bike. A cordless mower. Two or three tool packs on a charger. A scooter the kids ride. A spare pack for the pressure washer. Every one of those is stored energy sitting on a shelf, usually on a charger, usually unattended, usually against a wall shared with the house.
That is a different fire than a knocked over gas can.
The failure mode is what makes it different. A damaged or overheated cell can go into thermal runaway, a self feeding reaction that generates extreme heat very quickly, produces heavy smoke, and can reignite after the visible flames are out. Water does not reliably end it. Waiting it out does not either.
So a few habits, none of which require buying anything.
Charge on a hard, noncombustible surface, not on a wooden workbench and not on a carpet remnant. Keep the charging area clear of cardboard, sawdust, rags, and fuel containers. Do not charge overnight or while nobody is home, which is exactly when most people do it because it is convenient.
Use the charger that came with the device. Mismatched and aftermarket chargers are a recurring theme in incident reports.
And think about where the charging station sits relative to the wall that connects the garage to the house.
That last point is the one homeowners underestimate. In an attached garage, the shared wall and ceiling assembly is a fire separation, built to buy the people inside time to get out. Once fire damages it, restoration is not new drywall and paint. The assembly has to go back to code, which typically means fire rated board on the garage side, a self closing door, and sealed penetrations where ducts or wiring pass through. Skip a step and the inspector catches it, usually after the finish work is already done.
Smoke is its own problem. Battery and synthetic material fires leave residue that behaves differently from a wood or paper fire, and it travels. Anything stored in the garage is in its path, and so is the attic space above if the ceiling was breached. This is why garage fire restoration crews in the Twin Cities test for soot penetration well past the room of origin instead of scoping from what is visible.
Worth knowing what to do with a pack that is already misbehaving, since that is the moment most people improvise. Stop using anything that swells, leaks, smells odd, or runs unusually hot. Do not open it and do not attempt a repair.
Disposal is its own trap. Federal consumer safety guidance on preventing fires with micromobility devices is explicit that lithium batteries never go in household trash or general recycling, and should go to a battery recycler or hazardous waste collection point instead. The same guidance covers the charging rules above, including staying present while a device charges and using only approved replacement packs.
None of this is an argument against battery powered tools. They are better than what they replaced and they are not going away.
It is an argument for treating the corner of the garage where four chargers live with the same caution you would give a can of gasoline. Right now most people do not. They treat it like a phone charger, because that is what it looks like.