Why is my iPad 2 not registering that it is charging?

Hello,

My iPad 2 doesn't register that it is receiving a charge. However, if I leave it plugged in when it is off, when I turn it back on the battery has been charged. I have not sat down and quantified the battery charge % change over time, but it seems like it is charging slower than it was two weeks ago when plugged in and off.

I have troubleshooted and know that it is not a problem with the iPad charger, charging cable, or wall outlet. My problems seem reminiscent of people who say their battery isn't reporting that it is receiving a charge when plugged into their computer's USB.

Do I need to replace the battery? Is there anything else that might need replacing?

I wanted to make sure that this was not a software issue since it still charges when off. I performed a software update generally around the time that my battery started to 'act up', but I did not perceive an immediate "update software ---> battery problems" relationship.

Thanks in advance to the iFixit community. Sorry about the length of my question, I just wanted to be precise.