Yesterday I was getting ready to go outside and do some work in the yard. First time since last Fall. I have my old Samsung Galaxy smartphone which has a shattered display but still works. I use it as a radio outside. I can leave it lying around and it's doubtful anyone would bother to steal it and if they do no loss really. I leave it hooked up to my PC so it's always charged. It was shoved back underneath my monitor out of sight. I reached back to get it and something didn't feel right. Pulled it out and looked at it. The front of the phone was raised up. At first I just though the cover was coming off where you change the battery but I quickly remembered that is on the back not the front. I flipped it over and took the back off to find this:
The battery had apparently shorted at some point and expanded to nearly twice the thickness it should be. Now what is weird is the phone was still working all this time. I could access files on it from the computer. It even lit up the display when I disconnected it from the charger cord.
Now with the history some of these batteries have this could have easily caught on fire. Luckily it didn't. So if you leave stuff with lithium batteries hooked up check on them. While they can go bad really fast this one was going bad slowly.