Home > Laptop Battery Help > Battery Power Ratings Explained

Laptop Battery Power Ratings Explained

What do the power ratings mAh, Volts, Whr and Watts mean?

MAh (Milliamperes) represents the amount of stored energy in your battery. 1000 Milliamperes = 1 Ampere. The more mAh capacity - the longer your battery will last. Several batteries from LaptopBatteryExpress.com have higher mAh ratings than your original battery brand. This does not mean that the battery is not the correct replacement, but rather it is a longer lasting battery. Voltage in a battery refers to the volume of electricity that is delivered to your computer. The amount of energy that comes from your wall outlet is far in excess of what you need to operate the tiny circuits of a computer. Hence your power adapter contains a brick or bar like box that decreases the energy to a much lower voltage rating. Each computer manufacturer designs their computers for the appropriate voltage requirement. Your battery pack will then be engineered to match the voltage of the power AC adapter. Laptop battery packs are composed of several battery cells that are wired together in series. By combining the cells in this fashion, higher volumes of energy can be delivered to your laptop computer. For laptop computers, each battery cell has a voltage rating of 3.6 - 3.7 volts. (3.6V & 3.7V are used interchangeably and refer to the same amount of voltage.)The difference is due to rounding the fractions of a volt up or rounding down.

CellsVoltage/Cell Formula Nominal Voltage
1 cell 3.6V or 3.7V 1 cell x 3.6 or 3.7V 3.6V or 3.7V
2 cells 3.6V or 3.7V 2 cells x 3.6V or 3.7V 7.2V or 7.4V
3 cells 3.6V or 3.7V 3 cells x 3.6V or 3.7V 10.8V or 11.1V
4 cells 3.6V or 3.7V 4 cells x 3.6V or 3.7V 14.4V or 14.8V

Computer batteries Typically double the cell count in the battery cartridge to provide longer run times. This doubling of the cell count does not increase the voltage but it will double the run time.

Many laptop makers have produced battery packs over time that have different voltage ratings. HP, Acer, Gateway, Dell & others have actually produced the same battery packs in different voltages over time as they changed the number of cells in the battery packs. On many of these batteries we carry an 11 volt version and a 14 volt version of the same battery for those who are unsure and unfamiliar with how voltage is determined in battery packs.

Many people are concerned about the voltage rating needlessly. Most batteries with a different voltage rating will still work correctly in the laptop. In no case will a different voltage rating harm your laptop. Most AC Adapters we commonly plug into our laptops are rated at 19 volts. The extra voltage provided by the ac adapter over and above the battery pack voltage is the excess voltage required to recharge the battery plus operate the laptop. Simply stated, your laptop will not be damaged at 19 volts of power when plugged into the wall socket and it will certainly not be harmed by operating on a battery voltage less than 19 volts. You can rest easy that a different voltage rating on a replacement battery will not damage your laptop.

Watts measure the amount of energy a device uses. This is a rating that will be found on your monitor and laptop PC, not your battery.