So I am trying to repair a small charger that powers up but doesn't charge anything (it does have an led that goes from green to red for charging.) Any idea why it wouldn't be charging.

 

This is a Utube video on one of those chargers. Theres a circuit diagram in the middle of the video The wire going to the sliding contact is most likely to break. Hardly worth repairing apart from a broken wire as they are so cheap.

 

The reson is that the electricity goes to the "LED", but not to the battery, if you use "eBay" you will prorably find a cheap one.