The Capacity of Laptop Batteries Explained

Laptop batteries are rated by, Voltage (V) and Milliamp-hours (mAh). Voltage is the rate at which energy is drawn from the battery and 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 the same laptop provided the voltage rating is the same. The voltage rating has to match that of the original battery or as recommended by the computer manual. Using a battery with a different voltage setting can seriously damage the laptop. The power ratings of most compatible/replacment batteries are higher than the original manufacturers' batteries. This will not damage your laptop, in fact, it simply means that these batteries in many cases last longer than original manufacturers' batteries. Ask the experts like PowerUp on compatible replacement laptop batteries.

The run time of a laptop battery will vary on individual notebook computers, based on the applications being used (i.e. high graphics, 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.

The Chemistry of Laptop Batteries Explained

Laptop batteries come in all shapes and sizes also differ in their chemical composition. The chemistry of a battery refers to the chemical make-up of the cells inside the outer casing. The most common chemistries used in laptop batteries are:

NiCad (Nickel Cadmium) This is the oldest technology and is the least commonly used nowadays. NiCad batteries are prone to the Memory effect and are heavier than the newer technologies. NiCad is not environmentally friendly chemistry as it contains heavy metals, which cannot be disposed of in landfill sites. Most manufacturers have stopped producing batteries of this type chemistry. As an end user it will be increasingly difficult to source these batteries. The best alternative is external battery packs.

NiMH (Nickel Metal Hydride) these batteries are less likely to be prone to the memory effect and have a much better power to weight ratio than NiCad. This is a commonly used chemistry. These batteries are also being phased out by most manufacturers. However, many have lithium-ion versions that are compatible. Always consult the manufacturer or a reputable laptop battery supplier.

Li-Ion (Lithium Ion) - This is becoming the dominant technology due to its excellent power to weight ratio. Such considerations are becoming more important as mobile devices become smaller and lighter and battery weight becomes significant. Another plus point for Li-Ion is that it doesn't suffer the memory effect at all. These batteries do have a tendency to lose charge quickly towards the end of their effective life span. If this starts to happen the battery must be replaced.

These three technologies are quite different in the way they charge and therefore should not be substituted unless the device has been designed to take different chemistries. The owner's manual will describe which batteries are suitable.