Shuffle charging light turns green then orange again

To put it simply, when I plug my iPod shuffle in to charge, no matter whether it's a fast or slow charge USB wall adapter or a computer, it appears to charge properly. The orange light turns on, and after a couple hours the green light turns on, just as expected. However, trying to leave it charging for the requisite 4 hours to get them to 100%, they turn orange again. I have very little history, and it's possible the battery is just shot? I'd prefer to not replace it yet.