When my Samsung Galaxy Grand duos battery level comes to 80%, the phone goes off.

[AC Question]

This happens repeatedly. I didn't upgrade my phone. It is at the status of as purchased. I didn't installed any new app too recently. My kids are playing the games in my phone. Don't know if they pressed a wrong button. Recently I tried to charge the phone using a mobile charger. I don't know if this caused the problem.

 

[belodion]

Have you had the battery checked? It may be faulty.

Posted via the Android Central App

 

[Mahinda Pandithage]

How can I check the battery? Though the phone goes to off, the battery still has the power. I can switch on the power and it shows 70% and goes to off. Again I can switch on. This means battery is ok I think.
I don't know if there is any other method to check the battery.
Cheers