There are many differentiating factors between laptop batteries, and it pays to understand the different specifications you may see when shopping for a replacement notebook or laptop battery. It is always a good idea to use a parts locator tool to find a compatible laptop battery for your model, but here are a few of the key specifications to look for when buying a replacement laptop battery.

Voltage

Each laptop and laptop battery runs on a specific voltage. It is important that the voltage be correct for your model. The majority of laptops run on a voltage between 7.2 and 14.8 volts.

Capacity

A laptop battery’s capacity is usually rated in mAh, or milliampere-hours. Generally, the higher the number, the longer a laptop battery can run before it needs to be recharged.

Cell count

Laptop batteries consist of smaller energy-storing units, called cells. Generally speaking, the higher the number of cells, the more capacity the laptop battery will have. This can depend on other factors, however. In lithium-ion laptop batteries, in general the more cells in a laptop battery the larger the physical size of the laptop battery will be, so if you are replacing a 6 cell laptop battery with a 9 cell battery, the replacement laptop battery may protrude from the laptop more than the original laptop battery.

Manufacturer

Most replacement laptop batteries will be made by the manufacturer of your laptop directly. Laptop batteries made by a third-party can also be an advantage, as they tend to be less expensive. If buying a third-party replacement laptop or notebook battery, ensure you are buying from a retailer with a satisfaction guarantee and a clear return policy, to ensure quality and compatibility.

Estimated Runtime

This is one of the vaguest specifications of a laptop battery. The estimated runtime is just that, the estimated amount of time the battery will last on a single charge. While the estimate will give you a broad idea of the battery’s runtime, it can still vary greatly depending on many factors such as applications used, hardware connected to the laptop, etc. Therefore, you should use this estimate more as a comparison between laptop batteries than a hard and fast number.