How do you clean battery acid from wooden floor?

The best approach here is to consider neutralizing the acid. a solution of baking soda and water will do the trick. Battery acid is strong and acidic. Any damage occurred to the concrete will be permanent. The effects you see from the acid coming in contact with the concrete will vary based on how much acid there was and how long it was left to etch into the surface. Hydrochloric and muriatic acids will eat the concrete paste from the surface and leave anything from small mica to larger sand and gravel aggregate finishes. Neutralize it immediately when not intended!

The orange you see is called acid "burn" and any concrete "rust" removers you find on the market will not be effective at removing acid burn. Rust removers are good for rust but may damage, reactive or spread acid burn making it even worse.

Bleach will only remove a small portion of the stain and the scrub brush on concrete will definitely cause permanent damage to the concrete. Once concrete is "spot treated" with improper tools, chemicals or techniques it can be permanently damaged. Battery acid stains are not rust and are a chemical reaction within the concrete.

If you try Hydrochloric Acid, Hydrochloric will only remove a maximum of 60% of the stain. It is very dangerous and will permanently damage your concrete. The only reason HCL Acid works is because it dissolves the cement past and takes a small amount of stain with it. Battery Acid Stains can travel up to 2" deep into the concrete.

There is only one solution that will work- it is a new product called F9 BARC (Battery Acid Restoration Cleaner) made by Front 9 Restoration, Inc.