Do I need a new battery for my Galaxy SII?

[Megan186]

I've had this phone for one and a half years and this problem has just started. My phone could have as much as an 80% charge and it will suddenly start flickering slightly (like it's struggling to power the screen) and die. If I try to power it back up, the phone will say the battery is dead or it will boot up with 5% life left. If I leave it off for 20 minutes, it boots up just fine.

I've tried googling this problem, and people have said it might be the charge cord or try battery calibration. I have four different chargers (car/kindle hd/misc usb chargers) and have tried battery calibration and this is still happening.

I thought maybe it was overheating, because this only happens when I'm using the phone for 10min or more, but the phone doesn't always feel warm when it dies. Plus, it won't do this if it's plugged into a charger.

Should I get a new battery? Or does it sound like the phone might be damaged? I'm fine with getting a new battery or phone, but I don't want to end up having to buy both if the battery isn't the issue.

Thanks for the help!
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[carnageX]

I'd firstly try a factory reset if you can. Could possibly just be a software issue. if that doesn't work, or if it still happens... then I'd say its a hardware issue. Whether its a battery or phone issue... that's something you'd have to find out by either testing your battery in another phone, or testing a different battery in your phone.