Only works when plugged into wall charger

labergesteve, make sure that the battery cable is properly inserted in the little connector and that the clip is down to hold it into the connector. Let it charge a good while. I usually use a firewire connection to give the battery an extra boost since if it is to discharged, the USB and sometimes even a wall charger will not provide enough amperage to give it the initial kick. Of course you could also have a bad battery and there is also the possibility that the charging circuit on your ipod logic board has failed, which usually leads to a logic board replacement. Good luck and I hope you get it working.