Different Laptop Battery Power Ratings Explained

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Different Laptop Battery Power Ratings Explained

Knowing what the laptop battery power ratings mean is important for anyone who wants either a replacement battery or an upgrade to the laptop battery he or she already has. Purchasing a laptop battery can be confusing for consumers who are not familiar with power ratings and battery terms. It is a good idea to look at the individual battery specifications on a new laptop before making a purchase. While there are many choices available, it is important to choose a battery suitable for individual needs such as laptop and lifestyle requirements.

Anyone who wants to purchase a laptop or a laptop battery can benefit from learning about the different power specifications on laptop batteries. From calculating the expected battery life to deciding between one battery and another, buyers can use these specifications to improve their purchase experience. Finally, learning power ratings and specifications can help buyers to choose a quality laptop battery that suits their needs.

Laptop Battery Material

While any modern laptop battery is going to be a lithium-ion battery, older laptops might have a NiCad or nickel-cadmium, or a NiMH battery with nickel-metal hydride. Both batteries are out of date and are not as environmentally safe, nor as efficient, as lithium-ion batteries. However, these batteries are present and necessary on any laptop made for them so it is always important to check which types of batteries are being used in a specific laptop. Laptop batteries are either NiMH or lithium-ion although, for the most part, lithium-ion batteries have more power and are lighter than nickel batteries.

Laptop Battery Number of Cells

Many batteries feature a range of cells. On a laptop battery, the number of cells represents the number of battery partitions. Cells can range from one or two to upwards of nine and usually the more cells, the higher the capacity and life of the battery. A battery with more power cells has a longer battery life than a battery with fewer cells. Other factors can affect the life of the battery as well, but usually a nine-cell battery has twice the life of a six-cell battery.

Most multi-cell lithium-ion batteries also have a battery power management system to control power and prevent the battery from over- or under-charging. These batteries are often labelled as smart batteries, although almost all lithium-ion batteries have this function. Cells are typically matched to similar state of charge (SOC) cells, although any that are mismatched are labelled with the lowest SOC for any single cell present.

Laptop Battery Capacity

Every battery has a capacity rating, although it might not be quite as obvious as the factory '7.5 hours' or '11 hours'. The voltage, expressed in volts, and the electric current, expressed in amperes or amps, or milliampere-hours (mAh) can also be used to calculate the exact battery life or battery capacity. These specifications are important for anyone who needs a specific battery capacity, or for anyone who would like to find a battery with a large capacity.


The voltage rating on a laptop battery is generally expressed in volts (V). Typically, laptop batteries are rated with a number such as '10.8 V'. Voltage is used to measure the amount of pressure produced by the positive and negative energy inside of the battery. As such, it can be used to measure the amount of power present in the battery. The more volts present, the more power can be pulled from the battery at once. Surfing the web often requires minimal voltage while watching DVDs or playing games via an optical drive requires maximum voltage. Usually, batteries are equipped to work well with any sort of power usage, which is another case where the power management comes in.

Ampere Hours

Ampere hours are often expressed in milliamperes, or 100th of the rating of a full ampere. An ampere hour is used to measure the amount of time that the battery can be used before running out of power. For example, 1,000 mAh is 1 Ah, which is an easy method of calculation for anyone trying to decide a laptop battery's life. Essentially, mAh or milliampere hours is a direct way of measuring how long a battery lasts.

Calculating the Laptop Battery Life

Buyers can use the above information to calculate a laptop battery's life. An easy method of calculation is to look at the mAh and compare it to the mAh rating of other batteries. A simple rule is that the higher the Ah, the longer the battery life of the cell. For example, 500 Ah is half the battery life of 1,000 Ah, or one quarter the battery life of 2,000 Ah. The more power used by a computer, the faster the battery drains. Unfortunately, exact power usage in hours cannot be calculated because different types of use require different amounts of power. Watching a DVD drains a battery more quickly than surfing the web, but it is impossible to calculate how much of a user's time is spent on each application.

Some battery makers specify the average of a battery's life. However, most manufacturers specify the maximum battery life such as '11 hours', which means that the battery can last up to 11 hours if the laptop is idle and not running an optical drive. Battery life might be as much as half or less for heavy power-using applications and extensions including optical drives and connected USB devices.

A simple calculation for finding expected watt hours of a battery is to multiply the volts and the amperes. Ampere hours can be found by dividing milli-amperes by 100. For example, a 2,500 mAh rating can be condensed to 2.5 Ah. This rating can then be multiplied by the volts to get the watt hour rating. For example, 2.5 Ah × 14.4 V = 36, which is the number of expected watt hours. Watt hours is the amount of electrical power that the battery can supply for one hour. In this case, the battery could supply 36 watts in one hour. A good comparison is that this battery could power a 40-watt battery for almost an hour. A typical laptop uses between 14 and 45 watts, although as little as 3 to 1 watts or less while in sleep mode.

Choosing a Laptop Battery

There are many factors to choosing a battery, and in some cases, it depends on what the battery is being purchased for. Anyone purchasing a laptop battery to replace an older battery must choose a battery that is suitable for the computer it should power. On the other hand, anyone who is shopping for laptops and wants to compare the laptop batteries of various models can simply compare the battery ratings, including number of cells, power rating, and expected life.

Purchasing a replacement battery requires extra considerations but mostly requires that the battery be compatible with the laptop. Standard laptop batteries can be purchased from the laptop manufacturer, but likely at a premium cost. Laptop batteries can also be purchased from online stores at a much lower cost.

To purchase a replacement battery, check the model number on the old battery or check the manufacturer website for a list of compatible batteries. While it is important to choose a model recommended by the laptop manufacturer, it is not important to choose the same power specifications. Many people choose to upgrade their battery by purchasing one with more cells, more ampere hours, and more voltage. In this case, the only real specification is that the battery fit into the computer and that it provide the minimum amount of power necessary for the laptop.

Buying Laptop Batteries on eBay

eBay is an excellent place to purchase both new and used laptop batteries so whether searching for a replacement battery for an old computer, or looking for a brand new battery, you can likely find it on eBay. However, because of the wide range of models available, it is important to research and find the models you need before going on the site. Usually, it is a good idea to check the computer owner's manual and manufacturer's website, or the specifications on an older battery.

Next, you can easily search for an appropriate battery by typing the model number into the search bar on eBay. Try browsing the results and comparing prices, specifications, new or used conditions, and location of the seller. Options such as postage cost and estimated delivery time can also be considered, especially for anyone who needs a battery in a hurry. Checking with the seller and asking any questions is also a good idea before purchase.


Purchasing a laptop battery requires that the buyer pay careful attention to the type of battery, the power rating, and the battery model number. Older batteries might require a nickel-cadmium or nickel-metal hydride, and some newer laptops might also require these batteries. It is always important to check which type of battery is being used. Usually, the battery type can be found on the laptop near the computer power specifications.

Buyers can choose a battery based on the number of cells, as well as the power output. Usually, voltage and amperes are the important factors for determining battery power life. The more ampere hours that the computer is rated for, the longer the battery lasts. It is also important to consider how the computer is used for as this also affects power usage. After calculating their needs and the battery specifications, buyers can choose to purchase a battery on eBay, from an electronics store, or from the laptop's manufacturer.

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