| Three main types of rechargeable batteries are | | | | new had held devices are nickel-cadmium |
| used in newer technology hand held devices. | | | | (NiCad),nickel metal-hydride (NiMH), and the |
| Scientists are constantly trying to develop | | | | newest, Lithium Ion (Li-Ion) batteries. |
| batteries with better technologies that make | | | | Nickel Cadmium, or NiCad batteries are the least |
| them faster, more powerful, and more lightweight. | | | | expensive of the three types, because it has the |
| In the past, the only type of rechargeable battery | | | | least power. They are primarily used in portable |
| available was a lead-acid battery, which contains | | | | phones, power tools, and other hand held devices. |
| liquid and must be kept ventilated in an upright | | | | They are more practical than lead-acid batteries |
| position. Though still used in autos and | | | | because of their increased power and light weight. |
| motorcycles, scientists have developed | | | | They also have an advantage over alkaline |
| gel-batteries, where the liquid is semi-solid and will | | | | batteries which are not usually rechargeable. |
| not spill. These batteries, most commonly used in | | | | |