Fire Extinguisher Fun

I got a few unwanted carbon dioxide fire extinguishers, now various bit of my house and garage has an extinguisher.  My old one can be retired and I may let it off with my niece and nephew!  I first worry about storing it in a car, but then, in theory it is okay up to 120F, which in a hot car in England it is still practically impossible to reach 45C, I will leave it in for now.