The Harmony 650 does not have rechargeable batteries . It uses two AA's. I have three of the Harmony 700's which do use rechargeable batteries. The first one from several years ago came with a charging cable and plug. The other two only have the USB cable. I have run into an issue with all of them having difficulty charging; but so far have been able to fix it by removing the rechargeable batteries and then putting them back in. I can't answer why yours are not holding a charge.