I was carrying a battery in the floorboard of the backseat area of the car. I was going to return it to be disposed in a week. In the meantime, it tipped over and a good amount of the battery acid spilled into the carpet of the backseat area behind the driver.

image of spill

I have a few questions: 1) is the liquid very harmful to the touch or harmful to breath air in the interior?

And 2) how would I approach getting this carpet cleaned and back to normal? Or is the carpet a loss and should be replaced?

Thank you!

3 Answers 3


Yes, the liquid and vapors are harmful. Use plastic gloves and face-shield while handling the battery and cleanup. Open the doors and allow the car to air out a little vacate some of the fumes before cleaning up the acid.

Liberally (Use a lot!) cover the spill with baking soda. This will neutralize and soak up the acid. This will take 30 minutes to an hour and will turn to a paste.

Now use a carpet cleaner, steam cleaner, to wash the carpets with hot soapy water. Let air dry.

The length of time exposed and concentration of the acid will determine if the carpet will need to be replaced. There isn't anyway for us to know for sure.

  • 4
    I'd suggest nitrile gloves, but yes, nasty stuff. The sooner you get on this, the better. The longer the acid is left to sit, the more carpet it will chew up (destroy). It will also get onto the sealed/painted metal panels below the carpet and padding and will cause deterioration to start there as well. You cannot start the clean-up soon enough. Mar 17, 2017 at 20:09
  • 1
    Paulster2 makes a good point; always make sure you verify the appropriate type of glove for the type of material or chemical you intend to clean up. You don't want the chemicals dissolving your gloves and then your hands. ansellpro.com/download/…
    – rob
    Mar 17, 2017 at 21:41
  • Everything needs to be taken out, all the way down to the naked floorboards. Throw the carpet away. You will never get all of the acid out of it. Be sure to put the baking soda on before water, and probably better to use distilled water. And don't be that jerk PO: when you sell the vehicle, declare this to the buyer.
    – Paul
    Mar 19, 2017 at 18:22
  • @Pᴀᴜʟsᴛᴇʀ2 thanks for the advice! Worked like a charm. 2 boxes of arm and hammer made a nice thick layer. It absorbed most of the acid visible above the carpet overnight and hardened like a thin layer of dried mud. Then I was able to break it up with the nozzle of a car wash vacuum and it sucked it right up. I've been trying to wash it with warm soapy water, but it seems like a lost cause. I will likely remove the section and replace it with carpet or hard mat.
    – Taterhead
    Mar 21, 2017 at 21:07

You've spilled sulfuric acid in the back of your car. This is a very efficient oxidizer and will happily eat it's way through many things (think Alien blood from the movies). It won't eat through as fast as in the movies as it's been diluted to roughly 37% acidity and if you're lucky, the battery was extremely discharged rendering the acid somewhat less effective.

@CharlieRB's advice is sound, use baking soda and water to both neutralize (baking soda), and dilute (water) to further reduce it's ability to eat into things. If you've left it for long and it's in contact with your floor boards in the car, it's likely already eaten through the paint and is etching the metal of the floorboards. The sooner you clean it up, the better.

Wear clothes you don't like, as they're likely to get ruined by the acid. Wear eye protection & gloves, wash up carefully afterward and change your clothes. Open all the doors to the car while you're working on the spill to provide as much fresh air for you to breath as possible. Put the clothes into the wash as soon as possible after you've finished, or at least soak them in your tub or shower to dilute any acid they may have gotten on them. If you don't, you're liable to find that you have some interesting bleached areas, if not totally burnt through.

A bit of an anecdote, I was filling the batteries on a Mike Boat. They required a very large volume of acid for the very large batteries to start the two Allison V-12 engines down in the engine room. The guy I was working with had decided to drink his breakfast (whiskey), and managed to dump one of the acid canisters on my legs. Fortunately I was wearing a pair of USMC BDU trousers which are very-very tough, and there was a running hose only a couple of feet away. I was able to quickly rinse off the acid, then strip off the pants so my legs wouldn't get burned by the acid.


I used the advice on here for a similar issue. The (new) battery acid was sitting on the floor of the backseat for 2 weeks before I saw it. After doing research I thought it was going to eat through my carpet and metal of the floorboards. I quickly drenched it all in water and then covered it in baking soda 3 times (until it stopped reacting) and then cleaned it all about a week later with a carpet cleaner. The carpet looks good now and there isn’t any visible damage.

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