Power Sources » Electric

Figure 1. Electric forklift.
Figure 1. Electric forklift.

Electric-powered forklifts are most commonly used indoors in warehouses. Unlike internal combustion forklifts, electric forklifts are quiet and generally non-polluting but present other serious hazards that must be addressed.

For information on the parts of a battery used in electric forklifts, see the Parts: Battery section of this module.

Electric forklifts produce zero emissions, virtually eliminate the hazard of carbon monoxide poisoning, and run more quietly than internal combustion forklifts. However, electric forklifts present other serious hazards that must be addressed.

Potential Hazard

  • Electric forklifts are powered by large lead-acid batteries, which must be routinely charged. The hazards and recommended practices for charging and changing batteries are reviewed below.

Requirements and Recommended Practices

  • Designate an area for the purpose of battery charging.

  • Make sure that the forklift is charged before using.

  • Recognize that heavy loads drain the battery more quickly.

Figure 2. Large installations should have a plumbed drench shower and an eyewash.

A properly equipped battery charging area will have:

  • No smoking.

  • Warning signs posted.

  • Adequate fire protection.

  • Ample and readily available water supply for flushing and neutralizing spilled electrolyte.

  • An eyewash able to provide a 15 minute flow. (Figure 2) Note: For large installations, there should be a plumbed drench shower and an eyewash.

  • A phone or other means of communication in the event of an emergency.

  • Adequate ventilation to avoid the build up of hydrogen gas during battery charging.

  • Soda ash or other neutralization materials in the immediate area.

  • A dry chemical, CO2 or foam fire extinguisher.

  • Means to protect charging apparatus from damage from trucks.

Figure 3. The battery charge gauge indicates over-discharging.

An electric forklift is designed to operate for one shift and then be charged on the next shift or overnight. Some employers routinely change batteries instead of charging them in the vehicle. The discharged battery is removed from the forklift and a charged battery is installed in its place.

Only trained personnel should charge and change batteries in electric forklifts. In addition to training in battery changing and charging procedures, these employees should be trained on emergency procedures in the event of an acid splash, including how to use eyewash and shower facilities.

Potential Hazards

  • Batteries are very heavy.

  • Batteries contain sulfuric acid that is highly corrosive and could be splashed on personnel servicing or changing batteries.

  • Toward the end of the battery charging process, batteries can give off highly explosive hydrogen fumes.

  • Contact with battery cells can cause electrical short circuits, which can burn unprotected skin.

Requirements and Recommended Practices

Always follow your facility's specific safety procedures. Follow the recharger manufacturer's recommendations for attaching and removing cables and for proper operation of your equipment.

Figure 4. Electric forklift properly positioned while changing battery. Figure 5. Battery hoisted from forklift compartment with lifting beam.  Figure 6. Battery charging area.  Figure 7. Eyewash station.
  • Properly position trucks and apply brakes before attempting to change or charge batteries. (Figure 4) [29 CFR 1910.178(g)(8)]

  • Use a lifting beam or equivalent material handling equipment when lifting the battery. (Figure 5) Do not use a chain with two hooks. This may cause distortion and internal damage. [29 CFR 1910.178(g)(4)]

  • Charge batteries in the designated battery charging area. (Figure 6) [29 CFR 1910.178(g)(1)]

  • Facilities shall be provided for flushing and neutralizing spilled electrolyte, for fire protection, for protecting charging apparatus from damage by trucks, and for adequate ventilation for dispersal of fumes from gassing batteries. [29 CFR 1910.178(g)(2)]

    • NOTE: OSHA Directive, STD 1-11.4 - 29 CFR 1910.178(g)(2); Battery Charging Stations for Fork Lifts and Other Industrial Trucks, 10/30/1978 states: "Battery charging" areas where power industrial truck batteries are charged only--no maintenance is performed, batteries are not removed from the trucks and no electrolyte is present in the area--are not subject to the requirement of [29 CFR 1910.178(g)(2)]. The charging areas shall be in compliance with [29 CFR 1910.178(g)(1), (8), (9), (10), (11) and (12)]. Personal protective equipment shall be used when and where required.

  • When charging batteries, pour acid into water. Never pour water into acid. [29 CFR 1910.178(g)(7)]

  • Care shall be taken to assure that vent caps are functioning. The battery (or compartment) cover(s) shall be open to dissipate heat. [29 CFR 1910.178(g)(9)]

  • Prohibit smoking in the charging area. [29 CFR 1910.178(g)(10)

  • Take precautions to prevent open flames, sparks, or electric arcs in battery charging areas. [29 CFR 1910.178(g)(11)]

  • Remove all metallic jewelry before recharging. Tools and other metallic objects shall be kept away from the top of uncovered batteries. [29 CFR 1910.178(g)(12)]

  • Wear personal protective equipment (face shield, safety goggles, neoprene or rubber gloves and apron). [29 CFR 1910.132]

  • Where the eyes or body of any person may be exposed to injurious corrosive materials, suitable facilities for quick drenching or flushing of the eyes and body must be provided within the work area for immediate emergency use. (Figure 7) [29 CFR 1910.151(c)]

  • Check the electrolyte level before recharging. Record the specific gravity with the hydrometer in the service log. Check the pilot cell.

  • Check the water level. Do not add water prior to recharging. Record in service log.

  • Check the voltage. If the battery has sealed vents, do not recharge with a current greater than 25 amperes.

  • Unplug and turn off the charger before connecting or disconnecting the clamp connections.

  • Attach the positive clamp (+, usually colored red) to the positive terminal first and then the negative clamp (-, usually colored black) to the negative terminal, keeping the proper polarity.

  • Turn off the charger if the battery becomes hot or the electrolyte fluid comes out of the vents. Restart charging at a lower charging rate.

  • Check water level after charging. Add distilled water or de-ionized water if water level is below level indicator. Record in service log.

  • Return battery to forklift with lifting beam and secure in place after charging. [29 CFR 1910.178(g)(4) and (g)(5)]

  • Check the indicator on the hour meter to see that battery is fully charged.

Under normal operating conditions, power industrial truck forklift batteries can be expected to remain in service for 2,000 work shifts or charge/discharge cycles. Implementing a proper battery maintenance program can increase the life of the batteries and help protect employees. Battery failure could lead to mechanical breakdowns and possible accidents involving forklift operators and/or other personnel.

Figure 8. Discharging a battery beyond the manufacturer's recommended discharge level over works the battery making recharging more difficult and may damage or ruin the battery.
  • Do not continue a battery in service merely because it continues to deliver power.

  • Do not exceed the service hours in the manufacturer's recommendations.

  • Do not over charge or under charge batteries.

  • Avoid discharging batteries beyond the manufacturer’s discharge level. This can result in permanent battery damage and shorten battery life considerably.

  • Warning signs of a low battery include slow starting, dim headlights, and the ammeter indicating discharge at high RPM.

  • Recycle or properly dispose of batteries. Spent batteries are a hazardous waste unless they are properly reclaimed at a lead smelter or battery recycler.

Figure 9. Water is added at the end of the charge by operator wearing PPE.

Battery acid is dilute sulfuric acid. Sulfuric acid is a clear, colorless liquid with an acrid smell. It is corrosive and can cause severe burns.

Potential Hazards

  • Acid splash, especially to the eyes.

  • Acid spill.

  • Corrosive burns.

Requirements and Recommended Practice

  • Wear personal protective equipment:

    • Wear chemical splash goggles or full face shield with safety glasses equipped with side shields.

    • Wear acid-proof gloves made of rubber or neoprene.

    • Wear acid-resistant clothing or rubber or neoprene apron.

    • Wear acid-resistant safety shoes or boots.

  • Employees who wear contact lenses should wear chemical splash goggles during battery charging. In the event of an acid splash to the eyes, the contact lens could hold the acid to the eye, making it more difficult to flush the acid away and causing more serious damage to the eye.

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Emergency Procedure in the Event of an Acid Splash

These are sample procedures. Your facility may have its own safety procedure, requiring employees to contact their supervisors or medical personnel either on-site or off-site. Consult the Material Safety Data Sheet for additional information.

If the acid splash is to the eyes:

  1. Remove safety glasses and flush eyes with clean water in eyewash for 15 minutes.

  2. Seek medical attention immediately.

  3. Report the incident to your supervisor.

If the acid splash is to the skin:

  1. Remove acid soaked clothing immediately.

  2. Flush acid contacted skin with clean water for 15 minutes.

  3. Seek medical attention immediately if redness or burns occur.

  4. Report the incident to your supervisor.

If the acid is swallowed and the victim is conscious:

  1. Remove victim from battery area and provide fresh air.

  2. Wash out mouth with large amounts of water.

  3. Give victim milk to drink.

  4. Do not try to induce vomiting.

  5. Monitor victim's breathing and condition. Start CPR if victim stops breathing.

  6. Use NIOSH approved acid mist respirator, if OSHA PEL ( 1.0 mg/m3) is exceeded or if respiratory irritation occurs.

  7. Seek immediate medical attention.

  8. Report the incident to your supervisor.

If the acid is swallowed and the victim is unconscious:

  1. Remove victim immediately from battery area and provide fresh air.

  2. Start CPR if victim stops breathing.

  3. Provide oxygen, if properly trained personnel are available.

  4. Seek immediate medical attention.

  5. Report the incident to your supervisor.

Figure 11. Sulfuric acid spill.

Sulfuric Acid Spill (In the event of battery breakage)

  1. Neutralize the spill with soda ash or baking soda. Use 1 pound of baking soda to 1 gallon of water.

  2. The acid reaction is complete when it stops fizzing. Make certain that the acid is neutralized by checking the pH is neutral between 6 and 8.

  3. Absorb neutralized material onto clay or other absorbent material, if necessary. If the spill is very large, contain the spill with earth or clay dikes.

  4. Brush under the battery connectors and remove all grime. Rinse the residue from the battery with clean water with a hose.

  5. Report the incident to your supervisor.

  6. Determine proper disposal by contacting local environmental authorities.

Flammable hydrogen gas is always present during battery recharging. Hydrogen gas is potentially explosive if allowed to accumulate in a closed area.

Potential Hazard

  • Ignition/explosion of accumulated hydrogen gas.

Requirements and Recommended Practice

  • Post no smoking signs.

  • Use non-sparking tools.

  • Prevent open flames, sparks, or electrical arcs in the battery charging area to minimize the danger of explosion.

  • Provide adequate ventilation.

  • Open the battery cover when charging, so that the hydrogen gas can vent better. This is especially important in confined areas where the danger of accumulation is greatest.