Galaxy s 3 overheating seemingly out of nowhere Phone is fairly new to me, I got it November or so. It's always worked just fine. Today I had it plugged in, walked into the other room for a few minutes and came back. Phone showed an error something like "Charging paused. system is too hot." So my Boyfriend told me to restart it and put in my extra battery (because I have two batteries for it). Did that, powered back up, was working on where in settings I could find the battery temperature and (less than 5 minutes)it told me something to the effect of "System overheating. all apps have been closed, phone can only be used for contacts". So I powered off, pulled out the battery, and now I'm nervous to try and turn it on again. 
Any suggestions? 

EDIT: I'm not rooted
I had an S4 for a while and now have a Galaxy Note 4. My family has the S5 and S6, I believe, and all of them have gotten very hot while charging at one point or another, but not with an error. 

Check to see if your charger reads 5V - 2A, which is what should be on the S3. You could try charging while the phone is off - just watch its temperature.