Has anyone made a secure area for charging and storing their tool batteries? The reason I ask is that every once in a while someone has a fire that they point back to a tool battery being charged. In my shop, I have 4 M18 chargers in a row and if one would malfunction, the whole building would likely be gone. At times a battery will be left on charge overnight. My normal MO is to get them off the charger, but then I just toss them on the shelf next to the chargers anyway. It seems to me a metal cabinet maybe double lined w/ sheet rock set up could be a good thing? Any thoughts? 