The Power of 18650 Lithium-Ion Batteries

Quite often, consumers are unaware of what is powering their laptop computers. When their machine needs charging, they plug it in, usually with the supplied battery pack. Although most users may not consider it important to know, that most battery packs actually contain several 18650 lithium-ion battery cells.

 In battery terms, these are among the most powerful cells available. Many devices utilize lithium-ion (or Li-ion for short), to supply power. A number of electric shavers for instance contain a Li-ion battery. In terms of voltage, 3.7 is often typical. With a full charge, they'll pack up to 4.2 volts! And yes, these cells are also made very small, sometimes in button form, supplying power to very small devices!

It should be noted that not ALL Li-ions are rechargeable. But for the purpose of this discussion, we're focusing on those that are.

Specifically, however, 18650 lithium-ion batteries are larger both in length and width than standard cells. The numbers, 18650, refer to length and overall circumference. Like most rechargeable cells, their power is rated in milliampere-hours (mAh). These mAh designations are often numbered such as 2200, 2400, 2600, 2900, and 3100, which all relate to the amount of energy. The higher the number, the more power the battery possesses.

Briefly relating back to overall size... many lithium 18650's will differ ever so slightly in length (measured in millimeters). This is mainly due to an added protection circuit. The circuit helps to prevent the battery from over-discharging since Li-ion cells can easily become damaged if their power is drained below a particular voltage. 

The protection circuit also prevents the cell from being over-CHARGED as well. These cells are very sensitive. They must be handled carefully, gently, and as described above, must never run-down too far, or be charged over and above their threshold. They can actually explode if severely mistreated!

18650 lithium-ion batteries also pack a punch, power-wise, when used in today's high lumen LED flashlights. In applications such as these, only one cell is required. The flashlights for which I refer to when using a 18650 cell, can produce up to hundreds of lumens of light! How many you ask? In some cases, as much as 800 lumens! This is near to the same amount of light as a 60w (equivalent) CFL bulb can produce. 

These tools can be small enough to fit inside a pocket, quite comfortably. Flashlight manufacturers have designed many of their lights, to be only slightly larger than the 18650 batteries that power it. 

One word of caution though, flashlights of this type, when turned on high, can literally get quite hot to hold. This largely depends on the units' ability to dissipate heat but also depends on the overall size of the light. Many, even if only five inches long, might only get moderately warm to the touch.

In terms of charging these powerful cells, when specifically used in an LED flashlight, special chargers are available all over the internet. Most will handle a 18650 battery as well as a variety of other Li-ion sizes.

So, it's easy to see how a lithium 18650 battery, and Li-ion cells in general, have found their way into the homes (and hands) of many modern consumers.