Change its energy storage requires some experience and requires exactly the same batteries. All batteries are not created equal and not all are made to be used in series or in parallel with each other and rechargeable battery requires a specific set of batteries. More manufacturers li-ion batteries do not generally sell Casio np-120 battery only certified battery manufacturers. Nevertheless, there are more and more "free trader" in emerging countries. Our Samsung ICR-1850 were, for example, available on a Chinese site.Nevertheless, we strongly advise against taking this path that could be dangerous for the battery, the computer and yourself.