I have had the S2 for a couple of weeks, and a couple of days ago I started getting a warning from the app Battery Monitor from fsinib. The phone shut down once. It gets good and warm but not too hot to touch. I am not using a case. The phone is not rooted. OS is 4.04 and everything is up to date. It has happened several times in use and also while charging. The in use was running two GPS apps for jogging side by side. The battery does not appear deformed. I called Radio Shack support that comes with the cell phone, they had me take the battery out while the phone was on and wait one minute then restart. This has not solved the problem, if in fact 111.2 F is too hot for the battery. RS support was fast and helpful. They are going to call back tomorrow to check if still happening. I can still return the phone if I must. I have read about runaway apps but I have all of the apps installed on two different tablets and never had a problem. How to test for runaway apps? In battery settings the screen is about 70% the OS is about 12%. Someone posted that a car charger that is outputting only .5a as opposed to 1.0a is bad for battery. How is this? If the battery is overheating is it pulling too much amps?