It's NOT a basement bud and as the note on the screen clearly stated- "Yes, the battery bank IS vented."
BTW, the "one spark and you'll blow up like Hiroshima" type stuff is UTTER BS. Not trying to be rude, but I KNOW THIS from experience. Tightening connections and working in a tight battery bank eventually you WILL create a spark- have never had a problem.
Now 110, that's another story. I got "clipped" one time with a live 110 feed and that WILL wake you up. 12 or 24 volts is another story, you'll hardly feel it. No matter how careful you are, eventually you'll get shocked if you are doing what you SHOULD be doing with your battery bank. Don't fear it, it's not a big deal.
Sorry I saw the statement this time. When I innitially watched it the video was having trouble and it jumped a bit. I was just worried about the toxic fumes over an extended period of time. It looks neatly put together by the way.
lol I love how people are all worried about being shocked by a car battery, and the look they give you when you touch live 12v neg and pos wires to your tongue. I think people get confused with the primary current and secondary current for the ignition.