Batteries in Laptop Computers

by Blythe Ruzarrio

One of the biggest complaints against laptop computers today is battery life. In the beginning, laptop batteries didnt keep the system up and running for very long. Battery life has been extended with new technologies, but like microwaves just not heating fast enough; we still want computer laptop batteries to last longer.

NiCad (Nickel Cadmium) is the oldest battery technology and is used the least in laptops today. NiCad batteries are heavier than the newer types of batteries. NiCad is not very environmentally friendly (green) as it contains heavy metals, which cannot be disposed of in landfill sites. Most laptop manufacturers have stopped producing batteries of this type chemistry. NiMH (Nickel Metal Hydride) are less likely to be prone to the memory effect (where batteries gradually lose their maximum capacity) and have a much better power to weight ratio than NiCad. These batteries are rarely being used by most manufacturers. However, many have lithium-ion versions that are compatible. Li-Ion (Lithium Ion) is becoming the major technology because it has excellent power to weight ratio. This is very important because no one wants a heavy laptop to carry around. Another positive aspect of Li-Ion is that it doesn't suffer from the memory effect at all.

Laptop batteries are rated by voltage (V) and milliamp-hours (mAh). Voltage is the rate at which energy is drawn from the battery. Milliamp-hours represents the capacity of the battery. The milliamp-hour rating corresponds to the run time of the battery. A battery with a high Milliamp-hour rating has a relatively longer run time than a battery with a low milliamp-hour rating.

Batteries with different milliamp-hours can be used on a laptop provided the voltage rating is identical. The voltage rating has to match that of the original laptop battery. Using a battery with a different voltage setting will seriously damage the laptop. The power ratings of most compatible/replacement batteries are higher than the original manufacturers' batteries and not damage your laptop. It simply means that these batteries will last longer than original manufacturers' batteries.

The run time of a laptop battery will vary on individual notebook computers, based on the applications being used. Different uses like graphic games, the number of times something is saved or retrieved from the hard drive and/or CD Rom drive, the memory of notebook, and chemistry and capacity of the battery. A realistic average run-time for a battery is 1.5 to 3 hours. Using devices like a wireless adapter on the laptop also drains the battery considerably. The life of a battery under normal use is around 500 to 900 charge-discharge cycles. This is about one and a half to three years of battery life for the average user. As the rechargeable battery begins to fail, the running time of the battery begins to decline.