We listened to you! Installing a bilge pump in our Pit! 

That's a good idea. I guess you never know what gases could be lurking around on the garage floor and settling in the pit. When I worked as a pipefitter at a shipyard in public works, Hydrogen sulfide (H2S) was always a concern in muddy, leafy pits. H2S can be produced from decomposing matter and is heavier than air. Stepping down into it can kill you in two breaths. You shouldn't have that problem, but charging a car battery above could produce H2S gas. The distinctive rotten egg smell would probably alert you though. I love following this build, it's shaping up nicely!

Using the fog machine for a visual test on removing the bad air was smart...

Pit has A/C! now if I can get that Keg sorted out! Lol

Wont the exhaust fan and the AC exhaust fan be competing for pressure to get outside. You might end up with the AC fan pushing warm air down the pit overpowering the pit fan, or at least slows the pit fan down. Id separate them personally.