Here's the whole story about my question that hopefully someone can answer.
This blue 3DS I've been working on will turn on with a battery fully charged. While the 3DS is on I plug the device in, the charge light comes on, the system shows it's charging the battery but when I leave it to charge, the battery actually drains like normal. I saw this after pulling the charge plug to find it had dropped one bar of power.
I've also noticed that if the 3DS is off and I plug the device in to charge, the charge light shuts off after 5 seconds.
I've checked over the fuses and looked at the charge port, they're fine and I don't see any cold solder joints. I'm at a bit of a lose here as to why the battery will not charge in the system. I've also tested the battery in another 3DS (that's worthless) and it will take a charge from that 2nd, red, 3DS.
So I seem to have a very odd situation here where a perfectly working battery will charge in other 3DS' but will not charge in the blue 3DS. Any ideas or suggestions for this problem?