No, not the kind "THE GRAY PANTHER"S" wear. If your battery is just a little low, just add water. Now if it's very low or was spilled over you can add a 50/50 mix of acid and water. If it's has not been used or charged lately, kiss it goodbye. The question is why is it low? Overcharging or just not checking the levels. Also is this a starting or trolling battery? If it's starting and has any age to it, I'll replace it. Not worth getting stuck.
The acid doesn't go away- just the water. If you add acid, you mess up the mix in the battery and it will croak. The specific gravity gets out of whack and the current doesn't flow properly. It will ruin the battery.
Oh, and on the battery/concrete deal, it just isn't so. Batteries will not go dead sitting on the ground. They are insulated by their plastic housings. Ever wonder why they can sit on a steel shelf and not go bad? Steel is a conductor as well. The adage about not putting them on the ground is an old one though- and it used to be true. When batteries were in their early stages of development, most were in wooden cases. ( Remember, "plastic" is only about 50 years old.) These old batteries would go bad sitting on the ground because the wood would leach the acid/water mix through the wood and provide a pathway for the current. They WOULD go bad over time. With the advent of plastic non-conductive cases, that problem went away. Try it sometime- charge up your battery and sit in the the corner of your garage- go back a month later and check it. It may lose some charge just as any idle battery will, but it sure won't be anywhere near dead if it was a good battery to start with.
I learned a few years ago that the 'old wives tale' of not placing batteries on concrete was false. Old habits die hard though and I usually still place them on a block of wood.
Placing them on a block of wood is not a bad thing though. I have seen this topic discussed on other forums and a battery 'expert' responded that concrete can cause some minor problems due to the temperature differences between the concrete floor and the ambient air.
UFM82 if the battery is charged up your correct, the acid in the plates. If discharged it's in the liquid. The degree depend on the state of charge. Tap water in find as long as it's not high in minerals(hard water). Well water can be a problem. As for the block on wood, it's more from the new style plates they use now. They have longer shelf life than the old lead style. More batteries are killed my their owners than are defective. Always charge the batteries as soon as possible after discharge. If possible run the battery down every once in a while, then charge. Heat kills batteries so don't overcharge. Do your self a favor and get a "smart charger" with a float circuit. It will pay for itself in the long run.