Inspiron 5482 Battery Issues

Hello,

A few months ago, I started having issues with the battery in my Inspiron. At first I would periodically get popups that said my charger wasn't the right wattage, which I ignored because I knew that I had the correct charger and that the popups were most likely just from the charger falling about halfway out of the port (I figured this was just caused by the charger being a bit old and wormed out, and I don't think this has anything to do with the port itself). After a while, I started getting blue screens when trying to turn on my laptop that always said something about windows having an issue with loading and starting up. I spoke to a family friend that works in I.T. and he said to reseat the hard drive and battery. I did both, but still kept getting the blue screen, and ended up taking the battery out completely and just started using the charger for power. My laptop worked perfectly for a few weeks, but now it'll hardly ever turn on. When I can get a little bit of power only the backlights on my keyboard will turn on, but they always turn off after 1-10 seconds. It's becoming more and more rare, but sometimes my laptop will turn on, and it works perfectly fine until it's turned off. 

I really don't know what the issue here is. For a while I've thought that the problem was my battery and charger just getting old, since I've had this laptop for nearly 3 years. As of right now I can't really afford to buy a battery replacement, and I'm scared to buy a new charger just for that to not be the issue. I'm aware that the issue could also be the charging port, but I'm not sure how to test that. I was wondering if anyone could help me address some of these questions. Let me know if I need to provide more information. 

Thank you.