Which batteries are compatible with the DeWalt DW9107?
From DeWalt support:

Unfortunately it looks like the battery charger will not charge a 18 volt battery that will work with the DCD950b. The charger charges up to a 14.4 volt battery and the DCD950 will take a 18 volt battery. The battery and charger you will need for the DCD950 is  Charger 388683-12 and battery DC9096.