Galaxy S4 phone says its charging, but its not?

A few weeks ago I accidently dropped my phone in water, but did the rice trick and then it worked. It took a while but it eventually started charging, internet.etc. Then 2 nights ago I was charging my phone while I was "oovooing" ( its like skype ) with my friends and I noticed the numbers on my phone charger were going down even though I was charging it. It turned off and wouldn't turn on unless I changed the battery with a fully charged one with a different phone. I've tried cleaning the usb port and checking everything in the phone but nothing helped. The phone says its charging and has the light on, but the numbers would decrease, even when im doing absolutely nothing. Can anyone help?
Added (1). S4 Charging problem? ( please help )

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