Which batteries work best in your cordless phone at home. NiCD or NiHM batteries? We find NiMH batteries are usually higher capacity and last much longer in your phone. For example, the CPH-515D battery works for many models of phone. Here is a link to see if this battery will work on your your phone: CPH-515D Cordless Phone Battery The batteruy is 2,4 Volts and 750mAh NiMH. Ultra high capacity.