Nickel Cadmium (NiCAD) batteries are the least expensive, but most common battery. For optimum performance, NiCAD batteries should be completely discharged before being recharged, and then be recharged for a full eight hours at a time. Failure to properly discharge / recharge a NiCAD battery can lead to diminished performance (i.e. the "memory" effect). Nickel Metal Hydride (NiMH) batteries will resist the "memory" effect; allowing the user to charge their battery whenever is convenient. Cellular Concepts tries to stock NiMH batteries for every phone they sell. We sell NiCAD and NiMH batteries at the same low price! Lithium Ion (LiON) batteries are also resistant to retaining a "memory," but normally provide a longer stand-by and talk time and less weight than their counterparts. LiON batteries are slightly more expensive than NiMH.