hi, thanks for using JA:
The very first thing to do is a full reset of the Galaxy. With this process we will verify that the problem is not a software issue. To do this follow the steps outlined bellow. Please note that all data will be deleted from the Samsung Galaxy S as a result of this procedure. This process does NOT delete data stored on the microSD card.
1. Turn the power off. If your Samsung Galaxy S is frozen, pull the battery out and reinsert it
2. Hold the Volume Down button
3. Press and release the Power button
4. You are now presented with a menu that allows for Fastbook, Recovery, Clear Storage, and Simlock
5. Select Clear Storage by pressing the Volume Down button
6. Press and release the Power button
7. Now simply confirm your decision: Volume Up for YES and Volume Down for NO. After doing this check if the phone is charging again. If not, go to the next step.
If resetting the phone doesn0t solve the problem, then the cause of the issue is the phone hardware. The problem is related either with the battery, the charger or the charger circuit in the Galaxy. The most probably cause is the battery or the charger.
We can check if the charger is in good condition with a multimeter. Do you have one?
The only way totest the battery is by installing other battery on your Galaxy S, and testing if it charges. If the phone charges the battery when the charger is plugged in, them the problem is the battery.
Regards! If that helped, don't forget to accept my answer!