iPhone 3G does not look to be charging past "red"

For when the charger stops at 1% and sticks there.

1. Power it off completely by pressing the off button and holding the home key down until it is totally off.
2. Remove the sim card
3. Reboot without the sim card
4. Sleep it
5. Put the sim card in
6. Wake it and usually it goes up to whatever "real" charge level the battery actually has.

With thanks to:
http://forums.macrumors.com/showpost.php?p=11949680&postcount=24