I just received my new battery for my Triumph and it came with acid tubes that I needed to use to fill the battery. I followed the instructions in this video https://www.youtube.com/watch?v=XBHdE1RtXaI, but as soon as I connected the acid tubes with the battery as per the instructions, I noticed a slight smell of rotten eggs. I've searched for it online, and it didn't seem like good news, so I brought my battery from the basement to outside, and it's currently sitting in the shed. As I've read that I might be smelling toxic gas, I put some fans in the basement and opened the windows. So I have two questions:

  • Is it true that what I smelled could be toxic and is it ok what I did to aerate my basement?

  • Is my battery toast or could it still be usable? And how do I go about finding it out? I've now put the cap on the holes and I don't seem to smell anything anymore coming out of the battery

2 Answers 2


The rotten eggs smell was from the acid. It's sulfuric acid which can carry a rotten egg smell when broken down. This isn't uncommon and nothing really to worry about. Obviously it's something you probably don't want to do in the house, but the worst of it is just the smell, so air out the area and that'll be good to go. As for the battery, there really shouldn't be an issue. If you've used all of the acid ampules to fill the cells, make sure they are topped up with distilled water (if needed) to keep them in good stead. Other than that, you can check voltage of the battery itself with a multimeter. It should be between 12.5-13.1vdc ... might be a little more, but definitely in that ballpark. If the battery is a bit low, you can always put it on a battery charger. If you go that route, charge it somewhere it can get air. Other than that, use it in good health.

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    The smell is from hydrogen sulfide. It's harmless in low concentrations ("slight smell" levels), but once it reaches "strong stench" levels, evacuate the area and call emergency services.
    – Mark
    Commented May 24 at 22:00

If you just purchased the battery there shouldn't be an issue. As for toxicity sulfuric acid vapor reacts the moisture in your mucous membranes in your nose, mouth, and lungs etc damaging the tissues. Good ventilation is essential. Safety first.

Always put the acid in first then the water. The reaction generates a lot of heat. Add the water slowly. The water absorbs the heat of the reaction. Doing the reverse could cause boiling electrolyte solution to erupt from the battery. Initially fill to a little under the top of the plates to allow for expansion. Allow any air bubbles to work themselves out. Charge battery slowly -trickle charge over time.

Add additional water to a battery only after it is charged. The lead plates thicken up causing the acid level rise in battery. Then after charged fill cells up to slightly above the plates leaving a little space to allow for gases to escape during discharge or charge cycles.

I realize this a repetition of some of what Paulster2 said since actaram is new contributor to this site I thought I would add a little bit more detail. I wasn't sure to make it a comment or a response.

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    Old chemist here. Never add water to acid. If any concentrated acid must be diluted, add the acid to water. (See link at end.) But for power sports batteries or any battery that is shipped dry, the acid that is supplied with the battery is already the correct strength and must not be diluted. Simply follow the directions that come with the battery. AGM batteries shipped dry also need time to absorb electrolyte before charging. Directions are always included. For acid safety, see: thoughtco.com/do-you-add-acid-to-water-608152
    – MTA
    Commented May 25 at 15:14

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