battery promblem

[Android Question]

Samsung s2 ,
when I turn on my phone it says the battery is overheating when the phone is at a normal temputure

 

[Hadron]

The temperature sensor will be built into the battery and reporting the temperature to the phone (though some cheap 3rd party batteries don't include a sensor, which is dangerous IMO). It could be that the battery is hotter than the phone, or it could be that the sensor is reporting the temperature incorrectly. Or if the weather is very hot where you are, it may not have to heat up so much to trigger a warning.

Is the battery old? It might just be beginning to fail, in which case a new battery will fix it.