Do I add distilled water to an empty battery?

If the batteries were, as you say, totally dry, they will not charge with only water added. Lead-acid batteries must have acid. However, I hesitate to add acid to old batteries; you might be asking for trouble. It is probably safer just to dispose of them.

No, you did not do a bad thing. The acid in a battery is an electrolyte - that is, a liquid that will carry an electric current. It allows the currrent to flow from one plate to another to store the charge on the battery.

Do NOT dump the water out of the batteries. There may have been some residual acid in them and the water may be dangerous. Take the batteries to a battery shop for service and testing. If they are still good the shop will have the acid to refill them.

If the battery is empty, then no. In your battery is a mixture of water and acid. If the battery naturally gets low it is because the water evaporated or boiled out during a heavy charge/discharge cycle. When the water evaporates the level of fluid in the battery drops, and the acid concentration increases, so adding water here returns the battery to the correct level and concentration, and everything is OK. If the battery is completely empty, then more than likely the acid is gone too due to a crack or leak or being turned over. Adding water will bring the battery to the correct level, but not the correct concentration.

Battery Acid can be bought at any Auto Parts Store. If the batteries were not dead, distilled water should be good. The fact that you can't recharge them makes me think they might be no good. Try one with acid and see what happens.

If the batteries and dead and dry, the lead surface PLATES OUT with oxygen as a lead rust. Once that happens the batteries won't take a charge anymore.

This is why "completely dead batteries won't recharge." Sounds like your batteries have hit this problem. You might want to try some of the auto zone product, but the odds are not great that it will work.

You use to be able to buy battery acid at most auto parts stores, but I don't know if you can anymore.

theres a product called electrolite for batterys at the auto zone check with the sales dude for and answer some times you need a differant product for marine or deep cycle

I think you can buy it at Auto Zone, but I'm not sure if that's what you need. Surely someone there will know, though, if no one here has the answer.

They probably aren't any good anymore, after sitting for a period of time.

lol! why did you fill it with distilled water?