Warning today car battery's in the US and light trucks are sealed units. It would be very dangerous to play around with them. Acid in car & light trucks battery's is very corrosive and burn flesh! If it gets in someone's eye call 911 ASAP. Also with the EPA you can run into other issues. It is cheaper in the long run to buy a new battery or take it to a mechanic or car dealer.

Here is a link to Material Safety Data Sheet's - https://www.sbsbattery.com/PDFs/MSDS-Battery-Wet-Acid.pdf Link came from Bing search.