Batteries smell like FARTS, make people think there is a gas leak

Unfortunately the sulfur smell that I was hoping was coming from the cheap Chinese charger was something else. The firefighters who came to our door as I was relaxing this afternoon described it as swamp gas a condition and smell that occurs when your batteries are something. I was embarrassed and compliant and I only now realized what the date is and I feel like an a******.  

A very teachable moment courtesy of nyfd/my inability to intuit that I should goggle eggfarts..