My Forklift Smells Like Rotten Eggs

It's the start of the day, and your lead hand approaches with urgency: “Boss, we have a problem. One of the forklifts smells like rotten eggs. What should we do?”

Forklifts and their batteries, when charging, should not emit a rotten egg smell. While a slightly acidic odor from a charging battery is normal, a rotten egg smell from a forklift battery is a sign of a problem.

The Rotten Egg Smell is Sulfur

Forklift batteries are made from lead plates, coated with lead oxide paste, and submerged in sulfuric acid.

When one of the cells in your forklift battery fails to accept a charge, the forklift battery charger continues charging, trying to bring the cell up to full voltage. The cell overheats and causes the sulfuric acid to boil, which results in the rotten egg smell.

Rotten Egg Smell Coming From IC Lift Truck or Car

If the battery is in an internal combustion (IC) forklift or car, the alternator could be overcharging the battery, causing the rotten egg smell. Be sure to check your alternator before replacing your battery unnecessarily.

Forklift Battery Smells Like Rotten Eggs – What Should I Do?

Forklift batteries are different from car batteries (learn more here). They are much larger, heavier (typically 1,600 to 3,000 lbs), and more expensive. If your forklift battery smells like rotten eggs while charging, follow these steps:

1. Turn off the charger.
2. Let the battery cool down.
3. Do not use the battery – red tag it!
4. Contact a professional battery and charger service.
5. Replace the defective cell or battery.
6. Check if your charger is functioning correctly.

What Happened? Why Did the Forklift Battery Fail?

You're likely wondering why the battery cell failed. If the charger isn’t the issue, the failure could be due to one of the 12, 18, or 24 cells in the battery shorting out.

Bad Warehouse Floor

One common cause is constant jarring of the forklift on rough, uneven floors. This can shake the lead oxide paste off the battery plates, causing a short. When enough material accumulates at the bottom of the cell, it creates a circuit that shorts out the cell.

Water Quality

Another cause could be poor water quality when topping off the battery. If the water is full of dissolved minerals, these can build up and interfere with the charging process, causing the cell to overheat and emit the rotten egg smell.

Manufacturer's Defect

Sometimes, a battery cell may fail due to a manufacturing defect. This can happen when the wraps around the cell tear prematurely, leading to material shedding and a shorted cell. Contact your battery manufacturer to check if your battery is eligible for warranty repairs.

Forklift batteries typically come with a warranty ranging from 3 to 7 years. Manufacturer defects usually appear early on, within the first year. After that, most batteries will work reliably until they wear out. The warranty beyond 3 years often offers a “short life credit” to encourage repeat purchases. If your battery is failing before reaching 8 years, review your battery charging, maintenance, and watering practices.

Replacement Forklift Battery

While repairing a lift truck battery, be prepared to budget for a replacement. If your battery is over 3 years old and a cell has failed, another cell is likely to fail soon. Don’t waste money on a failing battery. A failing battery will:

• Run hot.
• Lose charge before the end of a shift.
• Draw too many amps, increasing wear on forklift components.
• Consume more electricity during charging.