Battery Safety: Lithium-Ion & Lead-Acid

Batteries power cordless tools, lifts, forklifts and equipment. Lithium-ion batteries can burn intensely and re-ignite, and lead-acid batteries give off explosive hydrogen and contain corrosive acid.

• Construction
• General Industry

Lithium-ion tool and equipment batteries

• Use only the manufacturer’s batteries and chargers.
• Charge on a non-combustible surface, away from flammables and exits, ideally where someone can see it.
• Remove from service batteries that are swollen, cracked, leaking, very hot, or that were dropped hard or submerged.
• Store batteries cool and dry, with terminal covers on. Keep loose batteries away from metal (nails, coins, tools) that can short them.
• Recycle damaged batteries according to local rules. Don’t throw them in the dumpster.

Warning signs of a failing lithium battery

Lithium-ion cells can go into thermal runaway: one cell overheats, ignites, and heats the next one. Watch for:

• Swelling or a bulging case
• Hissing, popping or crackling sounds
• A sweet or chemical smell
• Smoke or vapor, even a small wisp
• Unusual heat while charging or sitting idle
• A charger that won’t recognize the pack or flashes an error

Charging rules for the jobsite

• Charging station on a non-combustible surface, away from exits and flammables
• Not left charging unattended overnight in a job trailer or gang box unless the site allows it
• Chargers plugged straight into a receptacle, not daisy-chained power strips
• Batteries allowed to cool before charging after heavy use
• Fire extinguisher nearby, and everyone knows to get out and call 911 if a battery ignites

Lead-acid batteries (forklifts, lifts, vehicles)

• Charge only in designated, ventilated areas, since charging produces hydrogen gas
• No smoking, flames or sparks in the charging area
• Eyewash station (or shower) nearby for acid splashes
• Face shield, goggles, acid-resistant gloves and apron when watering or handling batteries
• Use proper lifting equipment to change heavy batteries
• Equipment parked with brakes set before charging
• Supplies on hand to flush and neutralize spilled electrolyte
• Charger off before connecting or disconnecting the battery, to avoid sparks

Handling acid and water

• Add water only after charging (unless the manufacturer says otherwise), to the level shown, so the battery doesn’t overflow acid.
• If mixing electrolyte, always pour acid into water, never water into acid, which can boil and splatter.
• Use a carboy tilter or siphon for large acid containers.
• Keep vent caps in place and battery tops clean and dry.
• Keep tools and metal objects off the top of batteries. A wrench across the terminals can explode the battery or cause severe burns.
• If acid gets in your eyes, flush for at least 15 minutes and get medical help. See Eyewash & Showers.

Large lithium systems

Electric equipment, energy storage containers and electric vehicles carry high-voltage battery packs that can shock as well as burn. Only trained technicians should open or service them. Damaged packs can catch fire hours or days later, so isolate damaged equipment outdoors, away from buildings, and follow the manufacturer’s instructions.

Last updated: October 1, 2026