Lithium ion (Li-Ion) batteries are increasing in popularity -- if you check the label on the battery pack that powers your laptop or power tool, it's highly likely it contains Li-Ion cells. Each Li-Ion cell produces 3.6 volts and up to about 2,400 milliamp hours (mAh), approximately three times more than a nickel-based cell. One obvious advantage is the weight, as you only need one Li-ion cell for every nickel-based cell.
Voltage relates to the electrical force produced by a battery cell. Battery packs containing Li-Ion cells are wired in series, meaning that the voltage produced from each cell is multiplied by the number of cells in the pack. A 6-cell Li-Ion battery pack produces 21.6 volts, while an 8-cell battery produces 28.8 volts, meaning you get a 25 percent increase in voltage when using an 8-cell battery pack.
Milliamp hours (mAh) defines the endurance you can expect to get from a fully charged battery, but is affected by the mAh the electrical device needs to operate. For example, a battery producing 7,200 mAh will power a device that needs 2,400 mAh for three hours, but the same battery can only operate a 3,600 mAh device for two hours. The mAh produced from a 6-cell battery is 25 percent less than an 8-cell battery, but this doesn't necessarily mean it won't last as long because, as the previous example shows, a battery's endurance is based upon mAh needed by the device it powers. It is likely that a 6-cell battery will last the same time as an 8-cell battery, because the mAh requirement of a device powered by an 8-cell battery will be greater.
Battery packs used to be very heavy when they contained nickel-based cells, but the introduction of Li-Ion cells has meant an equivalent Li-Ion battery, producing the same voltage as a nickel-based battery, weighs as least 40 percent less. As individual Li-Ion cells contained in battery packs each weigh the same, it follows that a 6-cell battery pack is about 25 percent lighter than an 8-cell battery.
Manufacturers have been able to considerably reduce the size of battery packs since the introduction of Li-Ion cells; you only need to think back to the size of cell phone batteries a few years ago, compared to the size of today's cell phone batteries. As with weight, the number of cells in a battery pack affects the size, as proportionally each cell is an identical size. An 8-cell battery is therefore approximately 25 percent larger than a 6-cell battery.
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