Why do my golf car batteries smell like rotten eggs?

We recently installed new batteries into a customer’s golf car, charged them up full, and returned the golf car to the customer with instructions to put the golf car on charge after every use.

The next day I received a concerned call from the customer asking, “why do my golf car batteries smell like rotten eggs?”

Golf car deep-cycle Flooded Lead-Acid (FLA) batteries contain lead plates submerged in an electrolyte solution of sulfuric acid and water. When you plug in your golf car charger and the batteries begin charging a chemical process begins with one of the by-products being the release of hydrogen sulfide (H2S) gas and its characteristic “rotten egg” odor.

Is hydrogen sulfide gas harmful?

Hydrogen sulfide gas is considered very poisonous, corrosive, and flammable, but low levels of the gas may be tolerated indefinitely. In terms of toxicity, H2S gas is like carbon monoxide (CO) gas, which can be harmful and is commonly associated with automobile exhaust.

The human body, as well as many other organic systems, produce a small amount of the gas and is an essential biochemical signaling agent with the body.

Hydrogen sulfide is flammable, so caution should be taken to avoid open flames and ignition sources when moderate to high levels of the gas are present.

How do I get rid of the awful smell?

The best way to eliminate both the odor and any potentially harmful conditions is to simply allow air to remove the gas from the area. Most golf car sheds at golf courses are required to install air circulation systems to completely exchange the air in the “cart barn” a minimum of 5 times per hour. This avoids the build up of potentially hazardous or combustible levels and eliminates the odor.

At home, the simplest way to reduce the level of the gas is to open your garage door or park the golf car outside.

Will my golf car batteries always smell like rotten eggs?

The short answer is no. New golf car batteries tend to produce more H2S during the first few charging cycles, but quickly taper off after the formatting stage of your batteries is complete.

Additionally, your batteries may also produce a smaller amount of hydrogen sulfide gas when you give your golf car batteries an “equalization charge”, which purposely boils the solution in your batteries for a limited time. More about equalization charging in another article.


The rotten egg smell associated with your golf car batteries is hydrogen sulfide gas, a natural by-product of charging lead-acid batteries. It is a hazardous gas at moderate to high levels, but tolerable at low levels.
Open air or ventilation is the easiest way to eliminate it. Your batteries will eventually reduce the amount of gas produced.

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