Cordless tools get sluggish the moment the temperature drops. You pull the trigger, the motor spins slower, the pack dies earlier than it should, and you start wondering whether the battery is toast. It usually isn't. The pack is just cold, and cold changes how lithium cells deliver power.
This piece walks through the chemistry, the warning signs and the habits that keep winter runtime close to summer numbers. The mechanics come from a MakeUseOf explainer that broke down exactly what happens inside a pack when the mercury falls.
At a glance
- Lithium-ion cells lose usable capacity in the cold because the electrolyte thickens and ion movement slows.
- A pack that delivers 100% of its capacity at about 27°C (80°F) may only deliver roughly half at -18°C (0°F).
- The loss is temporary; capacity returns once the pack warms back to room temperature.
- High-draw tools expose cold-packs' weaknesses faster than light-duty tools.
- Ryobi's 40V manual sets about 10°C (50°F) as the minimum storage and charging temperature for 40V packs.
The chemistry in plain English
Pull the trigger and current takes two paths. Electrons flow through the motor while lithium ions shuttle between electrodes through that electrolyte liquid. Cold thickens the liquid. A 2025 review in RSC Advances flagged the extra viscosity as a major drag on cold-weather performance. Ions also slow down at the electrode interfaces and once they're inside the electrodes.
Each of those slowdowns adds internal resistance. More resistance means more of the pack's voltage burns off as heat before any of it reaches the motor. Tools run on voltage, so a colder pack means a weaker tool at the business end. The slower spin also means less air or less cutting force, which is why your leaf blower feels anaemic and your circular saw stalls mid-cut.
Why high-draw tools suffer most
A phone sips current. A circular saw, a heat gun or a leaf blower at full throttle gulps it. That high current draw magnifies every volt lost to internal resistance. The pack's protection board may also misread the voltage sag as an empty battery and cut power to protect the cells. Release the trigger, the motor stops pulling, the voltage recovers, and the pack runs again. One reset is fine. Repeated cutouts are a warning sign.
Repeated heavy-load cutouts in the cold are a leading contributor to early power-tool battery failure. The pack isn't dead, but the cycle stresses the cells.
Storage and charging rules
Ryobi's manuals for 18V and 40V packs both recommend charging at normal room temperature and warn against storing packs in unheated spaces or vehicles. The 40V manual sets about 10°C (50°F) as the minimum for storage and charging. Most attached garages sit cooler than that through winter, even if they feel fine to walk into.
A closet shelf inside the house does the job without heating a garage. Bring packs in an hour before a big job if you can; they don't need to be hot, just not freezing.
Our analysis
Cordless tool marketing loves cold-weather claims. The chemistry doesn't care about the marketing. Lithium cells are slower in the cold by design, not by defect, and the slowdown gets worse the harder the tool pulls. That puts budget packs at a real disadvantage in winter, because their higher internal resistance makes the same cold more punishing.
The smartest move isn't buying more batteries. It's matching pack to tool. High Performance or higher-capacity packs hold voltage under load better than compact ones. Save compacts for drills and lights. Give saws, blowers and heat guns a pack that can stomach the surge.
The other smart move is storage. A heated garage works; a closet works better and cheaper.
Worked example: say you're clearing the driveway
You grab your 40V leaf blower after a 5cm snowfall. The pack sat in the garage overnight at about 5°C. You start on the sidewalk and feel the usual power. You move to the driveway, the trigger stays pinned, and within ten minutes the pack cuts out mid-pass. Release the trigger, pull again, it goes another short stretch and cuts again.
That's textbook voltage sag under sustained heavy load on a cold pack. Two habits fix it. First, store the pack inside the night before, or swap in a pack that came off a warm shelf. Second, use your biggest battery for the long pass and the smaller one for the tight spots near the door. If the blower keeps cutting under boost, stop and warm the pack; you risk shortening its life otherwise.
What to watch next
Watch the manuals, not the marketing. Manufacturers keep tightening cold-weather guidance as more data comes in on field failures. Expect future packs to publish a tested minimum temperature for both discharge and charge, and expect warranty language to lean on those numbers.
Bottom line: cold batteries aren't broken batteries. Warm them up, match the pack to the tool, and stop charging a frozen pack.
Key takeaways
- Cold is temporary; capacity returns when the pack warms, so don't write off a sluggish pack.
- Match pack size to tool load. Compact packs for light tools, High Performance or higher-capacity packs for saws, blowers and heat guns.
- Store and charge at about 10°C (50°F) or warmer for 40V packs; a closet shelf beats an unheated garage.
- Repeated cutouts under load are a warning sign. Stop, warm the pack, then continue.
- Don't charge a pack straight from a cold vehicle. Bring it inside first.
Frequently asked questions
Does cold permanently damage lithium-ion tool batteries?
No. The capacity loss is temporary and recovers at room temperature. Repeated heavy discharge in the cold, however, stresses cells and shortens lifespan.
What is the minimum temperature for charging a 40V Ryobi pack?
Ryobi's 40V manual sets about 10°C (50°F) as the minimum for storage and charging.
Why does my cordless tool cut off mid-task in winter?
Voltage sag under high load can drop below the pack's protection threshold, which cuts power to protect the cells.
Should I store tool batteries in the garage in winter?
Most attached garages drop below 10°C in winter. A closet shelf inside the house is safer and cheaper than heating the garage.
Do higher-capacity batteries perform better in the cold?
Generally yes, because lower internal resistance holds voltage under heavy load better than compact packs.