The chance of having a LiPo fire may be low, but they can happen to you, so what are you doing to protect your car, home and family from a possible LiPo fire? Here is my cheap solution.
I bought a fairly large .50 caliber ammo box from Amazon.com marketplace for $5 plus shipping. Ammo boxes are also available at Fleet Farm, I've been told.
First, drill a hole in the cover that is large enough to pass a Deans connector through it for charging. I used a step drill, which could make a larger hole than any of my other drills. Then I deburred the hole with a sanding attachment on my Dremel tool, to keep from cutting through the insulation on my charging cord.
Next, I set my batteries into the ammo box to see how many dividers I would need to make. Then I cut some Sheetrock that I had to fit the bottom of the ammo box, to insulate it from the heat of a smoking LiPo. This may be overkill, but that's my middle name! Then I arranged my batteries in the box to see how many dividers I would need to make. With dividers in place, if one LiPo ignites, none of the others will be damaged. My next job was to make the Sheetrock dividers, which run the length of the ammo box, and several smaller dividers made from several small pieces of Sheetrock taped together so they won't tip over. All of the dividers should be much taller than the LiPo packs, yet leave just enough room for Ziplock sandbags between the top of the dividers and the lid of the ammo box. Here are the finished dividers and floor. I left them loose so I can change the layout when I buy more LiPos. The photo on the right shows the batteries I'm storing.
Here are the batteries in the box: If I had more batteries, I'd store them vertically, instead.
The last thing you need is some dry sand. If it's damp and a LiPo ignites, the moisture will cause the LiPo fire to accellerate, instead of extinguishing it. LiPo fires are hard to extinguish otherwise, and a standard or chemical fire extinguisher won't work, either.
I filled two Ziplock bags with play sand, zipped them closed and duct taped the seal so it wouldn't open accidentally, and laid them on top of the dividers. If a LiPo goes off, the heat will melt the bag, dump sand on it and extinguish the fire. This won't stop a large quantity of hot, acrid and corrosive gas from venting out of the box, but at least your car or house won't burn down. If you're paranoid, you could always make a vent tube. (Paranoid is my other middle name.)