How to Store Lithium-Ion Power Tool Batteries for Winter
12 November 2026
Leaving a lithium-ion battery in an unheated garage from November to March is one of the most common ways to shorten its life, and the guidance from fire-safety agencies suggests it may be a safety problem too. The U.S. Fire Administration says lithium-ion batteries should be stored at room temperature when possible. It also says not to charge them below 32 degrees F (0 degrees C) or above 105 degrees F (40 degrees C). For anyone with a drill, string trimmer, leaf blower or chainsaw that sits idle until spring, those two lines explain most of what winter storage requires.
Why winter storage matters for lithium-ion tool batteries
Power tool packs spend much of the year in sheds, truck beds, basements and garages, and winter pushes those spaces to extremes. The National Fire Protection Association (NFPA) advises against storing batteries in extremely hot or cold locations. That covers an uninsulated shed in a hard freeze, and it also covers a spot next to a furnace, a space heater or a sunny window. Winter storage areas tend to be chosen for being out of the way, not for being stable in temperature.
The larger concern is what happens when a battery is stressed. NFPA says lithium-ion batteries can overheat, start a fire, or explode if overcharged or damaged. Damage doesn't always look dramatic. A pack that was dropped on a concrete floor, crushed under a heavy tool case or left with a cracked housing deserves a closer look before it goes into a storage bin. If it seems compromised, it should not be charged or stored with the others.
Cold by itself is mostly a performance and longevity issue, while heat and charging are where the fire-safety guidance gets firm. The trouble is that the two are connected in practice. A battery that has sat in a freezing garage and is then plugged straight into a charger is being charged outside the range the U.S. Fire Administration recommends. The agency's battery safety page puts the lower limit at 32 degrees F, so the sensible habit is to bring a cold pack indoors and let it come up to room temperature before it goes on the charger.
OSHA, which writes workplace rules, takes a similar line. It recommends storing lithium-ion batteries and the devices that use them in dry, cool locations. Dry matters as much as cool: a damp basement corner or a shelf near a leaky window is a poor choice even if the thermometer reads fine.
The storage target: temperature and charge
Put the recommendations side by side and they point to a clear target. Aim for a cool, dry, indoor space at roughly room temperature or a little below, with the battery partly charged rather than full. The University of Washington's environmental health and safety office says lithium-ion batteries should be stored between 41°F and 68°F. Its lithium battery safety guidance also says to charge them to approximately 50% of capacity at least once every six months.
That six-month detail matters for a winter plan. A pack put away in late fall is unlikely to reach the six-month mark before spring, but one that was already sitting unused when the cold arrived might. A simple routine helps. Note the date on a piece of tape on the storage bin, and if a battery has gone half a year without attention, top it up to about half and put it back.
The temperature window and the charge level work together. A battery stored full and warm is under more stress than one stored half-charged and cool, and the guidance from both the university and the manufacturer below leans toward a middle charge, not a full one. Many cordless tool packs have a built-in charge indicator of some kind. If yours shows only a few lights, treat two of four as a rough stand-in for half, and don't worry about hitting an exact number.
In practice, this means a closet shelf, a basement cabinet away from the furnace and water heater, or a spare-room shelf will usually serve better than the garage. If the garage is your only option, a bin you can carry inside is a better answer than a battery that stays out there all winter.
What not to do with stored batteries
Most of the avoidance advice is simple, and it comes straight from the fire-safety agencies. The following four points are the ones worth posting above the shelf where the batteries live.
- Do not store batteries in extremely hot or cold places.
- Do not leave them fully charged for storage.
- Do not block exits with stored batteries.
- Do not charge them outside the safe temperature range.
The exit point deserves a word because it is easy to overlook. NFPA warns against keeping batteries in an area that blocks the only exit out of a room. A basement workshop with one door, a mudroom closet or a cramped utility room can all fit that description. If a battery were ever to overheat, the last thing anyone wants is a stack of tool cases and charging packs between them and the way out. Keep the storage shelf to the side, with a clear path to the door.
The charging limit is the other item that people routinely break without realizing it. The U.S. Fire Administration's range of 32 to 105 degrees F covers most indoor spaces, but a pack that just came off a hot job site in a truck cab, or one that has been out in the cold overnight, may sit outside it. Letting a battery settle to room temperature before charging costs nothing but a little patience.
What the manufacturers say
General guidance is a useful starting point, but the maker of your tools has the final word on its own packs. STIHL, for example, says to store its batteries in a dry, secure area away from direct sunlight, at temperatures no lower than 14°F and no higher than 122°F. That is a wide survival range, and it is wider than the university's 41°F to 68°F window. The difference is worth understanding: the manufacturer's range describes what the battery can tolerate in storage, while the narrower numbers describe what is best for it.
STIHL spells out that distinction. For maximum battery life, it recommends an ambient temperature between 50°F and 68°F and a charge between 40% and 80%. It also says a STIHL battery should not be fully charged before storage. Those figures fit neatly inside the university's advice, which suggests a practical overlap: a spot around 50°F to 68°F, with the pack somewhere near the middle of its charge, satisfies both.
Readers with other brands should check the owner's manual or the maker's support pages for their own limits. Storage ranges and recommended charge levels vary, and a number that suits one battery line may not match another. Where a manufacturer gives a specific figure, follow it. Where the manual is silent, the cooler, partly charged, dry approach described above is a reasonable default, consistent with what the U.S. Fire Administration and OSHA advise in general terms.
One more habit helps here. If you own several packs, don't leave them in a heap. Store them separately in a way that keeps their terminals from touching metal objects and keeps them from being knocked around, since physical damage is one of the conditions NFPA links to overheating.
Fire safety and emergency precautions
Winter is also the season when homes are closed up, heaters run, and more things get plugged in. That raises the stakes on where batteries are kept and charged. NFPA's warning that lithium-ion batteries can overheat, start a fire, or explode if overcharged or damaged is a reason to avoid leaving packs on a charger for days at a time, particularly overnight or while you are away. Charge them when you can keep an eye on the area, take them off when they are done, and don't charge a pack that looks swollen, cracked or otherwise damaged.
For people who use tools in a business, a few additional points apply. OSHA says there is no specific OSHA standard for lithium-ion batteries, but the General Duty Clause and other OSHA standards may apply. In plain terms, an employer still has obligations to keep a workplace free of recognized hazards even without a rule written just for these batteries. A landscaping crew storing dozens of packs in a shop over the winter, or a contractor with a battery cabinet in a trailer, should treat the cool, dry storage guidance as part of that responsibility.
At home the same logic applies on a smaller scale. Keep the storage spot away from heat sources, out of direct sunlight, free of clutter and clear of exits. Know where the nearest way out is and make sure nothing you've stored gets in the way of it.
The simplest plan for the season is this: bring the packs indoors, charge them to roughly half, put them on a dry shelf in a cool room, write the date on the bin, and check them again before six months pass.