How pure is battery acid?
"The label may say it's pure battery acid but it's not a food-grade product and is not required to do a micro-analysis of the acid or even the containers it's bottled in. I think the point is that battery acid sold in an auto parts store, and Draino too by the way, is not intended for human consumption at any dilution. It is not held to standards for human consumption and therefore could contain any number of toxic contaminants that an auto parts-appropriate label is not required to disclose. For example, the sulfur used in production of battery-grade sulfuric acid could have any number of heavy metals in it...most would not harm a battery but could harm you if you consume it. Same thing with Draino....it's not tested or regulated by the FDA and the label is not required to disclose any impurities that could be toxic to us if ingested."
So is it pure distilled water + sulfuric acid, even when you consider the bottle?