Any rechargeable electronic device, from cordless power drills to cordless phones, has a battery pack. Often the replacement of these packs is extremely costly. The interesting facet to these battery packs is that they look like single, monolithic structures. This leads most people to believe that the entire battery pack is used for energy storage. Anyone with a screwdriver and a little time is able to deconstruct a battery pack to discover what once seemed to be a single object is actually a multitude of smaller objects — namely, rechargeable batteries — set into a housing. The housing is the costly part of any battery pack.
Whenever the battery packs on one of these devices fails, many corporations will tell you that you must replace it only with their patented materials, or risk harming your device. There is a grain of truth to this claim, and to be fully safe, one should not necessarily step outside of the bounds of company recommendation, especially if there are concerns about abiding by the rules of the product’s warrantee. If you are not worried about voiding the warrantee and want to both save some money and learn an invaluable new skill, then you can make your own battery packs.
Making battery packs is not very difficult, and it is certainly cheaper (usually about half the price) than buying a whole new battery — but up until recently, it was easy to do it wrong without extensive practice. Formerly, battery packs were made by soldering wires or small plates to the ends of the batteries to create a comprehensive whole. These wires would allow the power from one battery to flow into the next battery to create greater power.
Those days are long behind us.