The Differences in Batteries
- A basic classification of batteries, "cycle-life" refers to whether or not a battery is rechargeable. At the end of the scale are "deep-cycle" batteries, which can be discharged and recharged thousands of time. General household batteries generally have shorter life cycles; namely, primary and secondary.
Also called "disposable" batteries, primary cells lose power after one cycle. More expensive than primary cells, "secondary" cells can be electrically recharged to their original capacity. - Longer in length than in diameter, standard cylindrical batteries come in different sizes and are used in household electronic equipment. Non-standard batteries come in rectangular, button and square shapes, each with a positive and negative terminal configuration.
- The chemistry of each battery is the determining factor of power output. Standard-sized alkaline batteries generally deliver 1.5 volts, while nickel cadmium (NiCd) or nickel metal hydride (NiMH) secondary batteries of the same size have outputs of 1.25 volts.
Other than alkaline, the chemistry of a typical primary battery includes zinc-carbon and zinc-chloride. The longer-lasting lithium-ion secondary cell has recently been used to replace NiCd and NiMH batteries for laptops and mobile phones. Almost all automobiles use the efficient and reliable, but much heavier, "lead-acid" battery. - Expressed in "mAh" or "milliampere hours," the capacity determines the life -- in terms of time -- of a battery. Batteries, even if they have the same capacity, last for different numbers of hours depending on the current of the device. This means a battery with 2,700 mAh will last for 27 hours in a device with a rated current of 100 mA; 10 hours in a 270-mA device; and 1 hour in a 2,700-mA device.
