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Knowledge Base : Frequently Asked Questions : Large/RV/Marine Batteries FAQ : When Should I Add Extra Sulfuric Acid to my Battery?

When Should I Add Extra Sulfuric Acid to my Battery?

When you see your battery acid level begin to drop, you may wonder when and if it is appropriate to add acid, or just water.

We recommend that unless a battery was tipped over and all the acid spilled out, that you add only distilled water. Think of it like this: If you were to fill a pot up with salt water, and put it on your stove to boil, what happens? All the water will boil off, and you will be left with only salt. To re-create the original salt water mixture, you simply add straight water, because all the original salt is still in the pan, waiting to be re-suspended in the water. Batteries are the same way. All the chemical needed to make sulfuric acid is still in the battery, it is just the water that is gone. If you add more acid, you will be changing the chemical makeup of the battery which can lead to an incorrect sulfuric content.

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  • what to do if some qty. acidic water spilled out? How to regain the quantity of acid that spilled out?

    May 15, 2014 a 5:57 am
    • It is impossible to do so accurately. We do not recommend adding anything other than distilled water.

      May 16, 2014 a 2:18 pm
      • You answered my question and I’m glad I checked with you first! Thanks alot!

        Ninja Kev
        November 25, 2014 a 1:22 pm
        • Of course you recommend it, I assume for liability purposes… However, can one empty, ensure all the cells are empty, and refill them with electrolyte’s? FYI, I bought this 5lb dirt bike battery ($65), sealed it… then the bike sat for a year. Today I noticed the batteries cells were completely dry/empty when I reopened it. Just buying a container of Electrolyte’s $8.
          Thank you for your response. Disclaimer; I am responsible for any damage I may bring upon myself ;)
          V/R Justin

          October 5, 2014 a 5:46 pm
          • Justin it sounds like the battery is an AGM battery that you originally introduced the Acid to, and then sealed. Once sealed it is never recommended to open the battery, but as you have you would notice that it appeared dry, and that is because the fiberglass matting absorbed the electrolyte. It would not be my recommendation to add electrolyte to a sealed battery as all the electrolyte would most likely not be absorbed by the fiberglass matting.

            November 18, 2014 a 7:23 am
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