If a device is plugged into a battery charger and there is no visual indication of the phone charging, like a charging icon or battery level indicator, there is likely a problem with the battery , the outlet or with the charger. If the battery does not charge or will not hold a charge for long, it is more likely that the battery, rather than the charger, is faulty.
Checking terminal points to make sure that they are aligned with the device can also identify fault with the exterior wiring on the charger. Troubleshooting the battery can be done by using a device that detects an electrical current, called an ammeter, to determine if the charger is working properly.
According to How To Charge Batteries, "Check the continuity of the whole power cord and the relay itself, using the tester from the previous step. Also check if the grounded plug of the power cord is bend, broken or damaged. Look at the ammeter to see if it registers and if it does not, use a continuity tester to check the charger fuse. When the ammeter is not working properly, that usually means that there is an error in the DC circuit." Any rust, exposed wires or corrosion can also be the source of the issue. DoitYourself.com recommends cleaning the charger with alcohol and cotton swabs, as a last resort, to fix the problem.