Default [Q] Sudden battery drop

Recently, my battery percentage has been suddenly dropping like in the pictures below. It usually happens when I'm playing a game or doing some other battery intensive thing. I don't think the battery is really drained because it usually discharges to 1% and stays there for a long time in standby. But if I keep playing games, then it will shut down.

I am currently running Neutrino 3.02 and have had the same problem on CM 10.1 with the latest kernel.

I use ravilov's battery calibration app, but it doesn't seem to solve this problems. Does anyone know what the problem could be? Maybe the battery is too old or something else... Thanks for your help!
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