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Lithium-Ion Battery


Those who vape will be familiar with the term “lithium-ion (Li-ion) Battery” but many don’t understand these cells. They are different to your average AA battery used in your everyday household appliances. Lithium-ion battery cells is a form of advanced battery technology that uses lithium compounds. They are used in devices such as e-cigarettes, laptops, mobile phones, and torches and are popular for a variety of reasons. When Li-Ion batteries are being handled outside of a device and with an unregulated device, battery knowledge is key to prevent injury and harm.


Long Lasting

Li-ion batteries last up to 10 times longer than lead-acid batteries. On average, they last up to 1000 recharge cycles or up to 5 years. They require very little maintenance compared to other batteries but must be handled appropriately. To get the most out of your Li-ion batteries, they should be recharged when they are fully drained, and caution should be exercised to prevent battery wrap and insulator damage. If you are carrying li-ion battery cells externally, a battery case should be used.

Lightweight & Good Retention

Li-ion battery cells are much lighter than some other forms of powerful batteries. At the same time, they can still over a large amount of capacity and offer good amperage.


Lithium-ion batteries are relatively low in toxic materials, making them more environmentally friendly. Despite this, they should be disposed of with care.


On average, a Li-ion battery has a voltage of about 3.6V. This is higher than other battery variations including alkaline, nickel cadmium and nickel metal hydride which average about 1.5V. This helps to increase efficiency and helps to simplify power management.

No “Memory Effect”

Nickel Cadmium Rechargeable Batteries gradually lose their performance as they are repeatedly charged and recharged after only being partially discharged. It’s almost like the battery can only remember the small capacity. This is a problem with li-ion batteries but not as bad as it is with other battery types. For a long time, experts actually believed there was no “memory effect” with li-ion batteries.


Protection Required

Li-ion batteries require protection from being over charged and over discharged. This is one of the reasons why we do not recommend using Li-ion battery cells in unregulated mods and always recommend a battery charger. Good quality external battery cell chargers can assess the health of your cells and prevent them from overcharging. Regulated e-cigarettes come with a wealth of protection modes to help prevent battery damage.

Aging & Mismanagement

Li-ion batteries will deteriorate overtime. Their capacity will become less and less, and they will begin to lose performance. Mismanagement can also be a problem. For example, a lot of users don’t wait for their batteries to deplete before they recharge them. This results in reduced battery retention. Ever notice your iPhone battery dying on you quick? The biggest culprit of this in the short run is charging your iPhone when it is 50% or 70%.


The dangers associated with li-ion batteries can make them difficult to take on an aircraft. Airlines are familiar with the risks associated with li-ion batteries and take steps to mitigate these. For example, a limit on the number of batteries each passenger can carry. The problem with li-ion batteries is that they are flammable. When carried loose, if they make direct contact with coins or keys, they can start to vent. The same can happen if the battery wrap is damaged or if the insulator is missing.

Charging Lithium Batteries 

The best way to charge and recharge lithium battery cells is with a good quality battery charger that integrates safety features such as overcharge protection and short circuit prevention. Top battery charger brands include Xtar & Nitecore. Battery chargers offer many benefits including balanced charging, full restoration of capacity and amperage and restoration of over discharged batteries. We never recommend charging li-ion batteries via USB as this can cause issues such as premature battery deterioration, overcharge and imbalanced battery pairs. 


This small guide provides an insight into the most common form of battery cells used within the vaping industry. Expert knowledge of li-ion batteries is best obtained from the manufacturer or a battery specialist. Battery manufacturers and brands sometimes authorise their cells to be used within specific devices. Just because a battery fits within a device does not necessarily mean it has been authorised or meets the requirements of that device.

Frequently asked Questions

What is the size of an 18650 Battery?

The size of an 18650 battery is defined within the name. They have a diameter of 18mm and a length of 65mm. The “0” refers to a round cross section.

Are 18650 Batteries the Same as AA Batteries?

The short answer is no. In basic physical appearance, an 18650 battery is significantly larger than a AA battery. Technical differences include:

  • Voltage: The standard or nominal voltage of an AA battery is 1.5V. In contrast, the nominal voltage of an 18650 battery is 3.6V.
  • Size: The size of an 18650 battery is 18mm diameter and 65mm length. On the other hand, your standard AA battery only is 14.5mm in diameter and approx. 50mm in length.
  • Retention & Current: AA batteries generally have a capacity of 2500mAh on average. This is about the same as a K25 18650 battery. The main difference can be seen from the current of each variation. The maximum working discharge rate of an AA battery is usually around 0.75A, whereas for an 18650 battery, its about 3.2A.

Are 18650 Batteries Dangerous?

If 18650 batteries are handled incorrectly or mis used, they can be dangerous and cause harm and injury.

What are 18650 Batteries Used in?

18650 batteries are used in a variety of products, including, e-cigarettes, torches, and laptops. In the Tesla Model S & X, the battery packs use 18650 batteries that have been manufactured by Tesla.

Quick Tip: Watt’s Law

Wattage (P) = Current (I) x Voltage (V)


Defines the relationship between wattage, voltage and current.