Guide · Cordless and battery platforms
Lithium-ion tool battery safety
How to charge, store and retire cordless polisher batteries, from Health Canada, CPSC, Milwaukee and DEWALT, and why a shipped tool battery is dangerous goods.
Short answer
Charge tool batteries at room temperature where you can see them, away from soft surfaces, with the charger the tool maker specifies, and stop using any pack that is swollen, dented, cracked or damaged.[1][2] Keep packs away from high heat: Milwaukee says exposure above 130°C (265°F) may cause explosion.[2] If you ship a pack or a cordless tool, it is dangerous goods and must be declared to the carrier.[3]
Why tool batteries need rules
CPSC says high-energy batteries such as lithium-ion can overheat, cause fire and thermal burns, and that incidents have happened during use, storage and charging.[4] A cordless polisher pack is that kind of battery, and detailing puts it near water, heat and solvents, so the basic rules matter.
Charging
Health Canada's advice for lithium-ion devices:[1]
- Charge at room temperature, where you can see the device.
- Keep it away from soft surfaces such as a couch or bed.
- Do not overcharge.
- Do not use batteries that are swollen, dented or damaged.
- Use the charger that came with the device, or a compatible one from a trusted source with a CSA, cUL or cETL mark.
The tool makers add their own rule. Milwaukee says to recharge only with the charger the manufacturer specifies, because a charger suitable for one battery type may create a fire risk with another.[2] For a polisher, that means the platform maker's charger, not a "universal" one; see genuine vs aftermarket batteries.
DEWALT also advises storing and charging packs in a cool, dry place.[5] A detailing bay that is wet from washing is not that place: charge indoors, away from the hose.
Damage
| Sign | What the makers and regulators say | Source |
|---|---|---|
| Swollen, dented or damaged | Do not use | Health Canada[1] |
| Visible damage or cracks | Do not use; do not attempt repair or service | DEWALT[5] |
| Damaged or modified pack or tool | May behave unpredictably and cause fire, explosion or injury | Milwaukee[2] |
| Exposure to fire or high heat | Above 130°C (265°F) may cause explosion | Milwaukee[2] |
Health Canada and Milwaukee agree on the core rule: do not use a damaged lithium-ion battery.[1][2] Do not try to open, rewrap or rebuild a pack.
Storage
- Store packs in a cool, dry place, as DEWALT advises.[5]
- Keep them out of a hot parked car and away from heaters; that is not the cool, dry place DEWALT describes.
- Store them where you would notice smoke or swelling, not buried in a cabinet with polish and solvents.
Shipping and travel
Transport Canada says lithium batteries are dangerous goods, including those packed with or contained in devices such as power tools, and that shippers must declare them to the carrier. It also warns that some lithium batteries can overheat and catch fire.[3] UL Solutions says all lithium-ion batteries must be tested to UN 38.3 before shipping.[6]
If you return a cordless polisher or sell a pack, ask the carrier how to ship it. Carrier and marketplace rules differ, and we do not promise any route.
Next
Questions
Can I charge my polisher battery overnight?
Health Canada advises charging lithium-ion devices where you can see them, away from soft surfaces, and not overcharging. Charging while you are present and awake follows that advice.[1]
Is a swollen tool battery dangerous?
Treat it as unsafe. Health Canada says not to use batteries that are swollen, dented or damaged, and Milwaukee warns a damaged pack may cause fire, explosion or injury.[1][2]
How hot is too hot for a tool battery?
Milwaukee warns that exposure to fire or temperatures above 130°C (265°F) may cause explosion, and DEWALT advises storing and charging packs in a cool, dry place.[2][5]
Can I mail a cordless polisher with its battery?
Only as declared dangerous goods. Transport Canada says lithium batteries, including those packed with or inside power tools, are dangerous goods that must be declared to the carrier. Ask the carrier first.[3]