I can visualize it and IMHO it lacks a lot as far as adequate ventilation is concerned.
Here is a not so improbable scenario...
Battery or cell ages and goes bad. Battery emits a lot of corrosive fumes -- anything in that compartment will get saturated including wood and cloth. Metal will corrode.
Hydrogen gas goes straight up then vigorously wanders around on the ceiling looking for a way out. If it doesn't find a way then overhead a pocket of hydrogen is formed. H2S and H2SO4 are heavier. Battery boxes with inch and a half single vent exiting the box at the top will stop explosion and corrosion hazards.