Must confess I once took one of mine and left it in the trunk of the car for a couple of weeks. At the time it started doing the mad beeping Charlie was away for the weekend, I wasn't strong enough to pry the battery out of its tight little compartment to unhook it, and the noise was driving me bonkers.
By the time I brought it back in, the beeping had stopped and we could remove the battery without earplugs. Turned out the replacement battery was more than a new UPS by the time we'd factored in shipping and such, so the old battery was carted off to battery recycle land.