Sulphuric acid can cause severe skin burns and even blindness if it gets in contact with your eyes. Ingesting battery acid can damage the inner lining of the digestive tract, while inhalation may result in breathing difficulties. Read on to find out more about the dangers of battery acid.

Is battery acid dangerous?

Yes, battery acid is very dangerous as it contains sulphuric acid, which is highly corrosive even at relatively low concentrations.

Battery acid sign with danger symbolIn most lead batteries, such as those used in vehicles and solar power systems, the concentration of sulphuric acid typically ranges between 15% and 35%. However, some batteries contain as much as 50% sulphuric acid.

Being highly corrosive means battery acid can damage living tissue like skin, the inner lining of the digestive tract, and our respiratory system. If battery acid gets in contact with your eyes, it can cause sight problems and potentially blindness.


Inhaling sulphuric acid fumes can trigger a reaction in the lung tissue that causes the alveoli and air passage to constrict, which can lead to breathing difficulties. It can also cause dizziness and nausea as the brain’s oxygen supply is depleted. Other symptoms may include drooling and swelling of the throat and mouth.

Inhalation is less likely to be a risk under normal circumstances because sulphuric acid is not highly volatile. However, high temperatures may cause the acid to evaporate into fumes, thereby increasing the chances of inhalation. If someone does inhale battery acid, make sure they’re properly ventilated and immediately take them to hospital for treatment.

Contact with the skin or eyes

As battery acid is highly corrosive, it can cause severe burns if it gets onto the skin or into the eyes. In this case, you should thoroughly rinse the affected part with running water and seek medical advice.

Person washing a burn on their hand under running waterIngestion

Ingesting battery acid, even in small or trace amounts, is also dangerous. Battery acid can burn the lining of the digestive tract and stomach, which can be life-threatening.

If someone does swallow battery acid, do not induce vomiting; this may worsen the irritation and cause further damage to the digestive tract. You should also make sure the patient doesn’t eat or drink before they’re examined by a doctor.

What is the pH of battery acid?

Battery acid with a concentration of between 30% and 50% has a very low, highly acidic pH of 0.8.

Sulphuric acid is one of the seven strong acids. Its strength is not measured in terms of pH because the latter can vary widely depending on the concentration. Instead, it’s measured in terms of the dissociation constant or how the ions completely dissociate in an aqueous solution.

The other six strong acids are:

  • Hydrochloric acid (HCl)
  • Hydrobromic acid (HBr)
  • Hydroiodic acid (HI)
  • Nitric acid (HNO3)
  • Perchloric acid (HClO4)
  • Chloric acid (HClO3)

What is in battery acid?

Battery acid, specifically the type found in lead-acid batteries, is a sulphuric acid solution with the chemical formula H2SO4. It’s commonly diluted at 35% concentrations.

The acid acts as the electrolyte of the battery that supplies the positively-charged and negatively-charged ions. During charging, as direct electric current passes through the battery cells, reservoirs of negatively-charged and positively-charged ions are formed on opposite plates (cathode and anode).

This is how electrical energy is stored in the battery and, much like water in a dam, is then gradually released when in use.

Can battery acid burn your skin?

As a strong acid with a very low pH, sulphuric acid has a strong tendency to donate its protons.

In doing so, it can denature proteins by breaking down the hydrogen bonds between the amino acids. As a result, it unravels the structure of the protein, making it disordered. This is the mechanism that causes the skin to burn when battery acid comes in contact with it. The damage is caused by the breaking of the protein structure of the collagen in the skin.

How to treat a battery acid burn

To treat a battery acid burn on the skin, thoroughly wash the affected area with running water. Take the patient to hospital for proper medical attention if the burn is serious.

How to clean dried battery acid

Do not attempt to clean dry battery acid in your car or solar battery if you don’t have the proper skills and training. In most cases, it’s best to allow a professional to clean it or simply replace the battery altogether.

Battery acid leaking from a car batteryHowever, if you really have to clean dried battery acid, you’ll need to weaken or neutralise it first using a mild acid like vinegar or lemon juice. Be sure to use gloves and safety glasses or goggles. Never use baking soda to neutralise the dried battery acid as it can form a conductive paste that may cause the battery to short-circuit.

Avoiding contact with battery acid

The best way to avoid contact with battery acid is to allow professionals to do the work on your car or solar battery, such as cleaning or replacing the acid solution. Do not open the battery case for any reason.

If you do need to handle batteries, you should use proper protection, like goggles and safety glasses. Don’t drop the battery or expose it to high temperatures. To prevent contact with battery acid at home, always get rid of old batteries and be sure to follow the correct disposal procedures.

A pile of alkaline batteries