Help phone charges only when turned off, kinda...

[need help with charger]

Basically my phone hasn't been charging and only starts charging when my phone is turned off but will stay charged when turned on still in the charger, I went to the metro store and they couldn't replace it, I'm using the charger that came with my phone and have tried other chargers and outlets, this is really annoying and I would like help asap! I also have a Samsung Galaxy Core Prime if that helps, and its up to date on updates! Please help asap~

 

[AZgl1500]

how old is the phone, I am not familiar with it.

but, it sounds like a tired battery

 

[wadanohara]

how old is the phone, I am not familiar with it.

but, it sounds like a tired battery

I've had it for less than a year now.

 

[jefboyardee]

Having had no end of micro-USB cable problems, I suggest you replace yours.