Motorola is slowly facing out Nickel-Cadmium batteries in lieu of the superior Nickel-Metal Hydride batteries. You will find it even though some batteries are advertised as Nickel-Cadmium Motorola is now using Nickel-Metal Hydride.
Some of the main advantages of Nickel-Metal Hydride over Nickel-Cadmium batteries are capacity, no memory effect and just as important these batteries are more environmental friendly. Nickel-Metal Hydride or NiMH for short, are newer technologies providing better performance, especially with high drain devices. Not only do they deliver more power, and can be charged up to 1000 times, all without the cadmium toxicity concerns associated with Nickel-Cadmium batteries.
In short, NiMH batteries are much better than NiCd batteries and Motorola is not charging extra for them.